Add gdb_report_register_access_error command

[openocd.git] / src / server / gdb_server.c

/***************************************************************************
 *   Copyright (C) 2005 by Dominic Rath                                    *
 *   Dominic.Rath@gmx.de                                                   *
 *                                                                         *
 *   Copyright (C) 2007-2010 Øyvind Harboe                                 *
 *   oyvind.harboe@zylin.com                                               *
 *                                                                         *
 *   Copyright (C) 2008 by Spencer Oliver                                  *
 *   spen@spen-soft.co.uk                                                  *
 *                                                                         *
 *   Copyright (C) 2011 by Broadcom Corporation                            *
 *   Evan Hunter - ehunter@broadcom.com                                    *
 *                                                                         *
 *   Copyright (C) ST-Ericsson SA 2011                                     *
 *   michel.jaouen@stericsson.com : smp minimum support                    *
 *                                                                         *
 *   Copyright (C) 2013 Andes Technology                                   *
 *   Hsiangkai Wang <hkwang@andestech.com>                                 *
 *                                                                         *
 *   Copyright (C) 2013 Franck Jullien                                     *
 *   elec4fun@gmail.com                                                    *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program.  If not, see <http://www.gnu.org/licenses/>. *
 ***************************************************************************/

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <target/breakpoints.h>
#include <target/target_request.h>
#include <target/register.h>
#include <target/target.h>
#include <target/target_type.h>
#include "server.h"
#include <flash/nor/core.h>
#include "gdb_server.h"
#include <target/image.h>
#include <jtag/jtag.h>
#include "rtos/rtos.h"
#include "target/smp.h"

/**
 * @file
 * GDB server implementation.
 *
 * This implements the GDB Remote Serial Protocol, over TCP connections,
 * giving GDB access to the JTAG or other hardware debugging facilities
 * found in most modern embedded processors.
 */

struct target_desc_format {
        char *tdesc;
        uint32_t tdesc_length;
};

/* private connection data for GDB */
struct gdb_connection {
        char buffer[GDB_BUFFER_SIZE];
        char *buf_p;
        int buf_cnt;
        int ctrl_c;
        enum target_state frontend_state;
        struct image *vflash_image;
        bool closed;
        bool busy;
        int noack_mode;
        /* set flag to true if you want the next stepi to return immediately.
         * allowing GDB to pick up a fresh set of register values from the target
         * without modifying the target state. */
        bool sync;
        /* We delay reporting memory write errors until next step/continue or memory
         * write. This improves performance of gdb load significantly as the GDB packet
         * can be replied immediately and a new GDB packet will be ready without delay
         * (ca. 10% or so...). */
        bool mem_write_error;
        /* with extended-remote it seems we need to better emulate attach/detach.
         * what this means is we reply with a W stop reply after a kill packet,
         * normally we reply with a S reply via gdb_last_signal_packet.
         * as a side note this behaviour only effects gdb > 6.8 */
        bool attached;
        /* temporarily used for target description support */
        struct target_desc_format target_desc;
        /* temporarily used for thread list support */
        char *thread_list;
};

#if 0
#define _DEBUG_GDB_IO_
#endif

static struct gdb_connection *current_gdb_connection;

static int gdb_breakpoint_override;
static enum breakpoint_type gdb_breakpoint_override_type;

static int gdb_error(struct connection *connection, int retval);
static char *gdb_port;
static char *gdb_port_next;

static void gdb_log_callback(void *priv, const char *file, unsigned line,
                const char *function, const char *string);

static void gdb_sig_halted(struct connection *connection);

/* number of gdb connections, mainly to suppress gdb related debugging spam
 * in helper/log.c when no gdb connections are actually active */
int gdb_actual_connections;

/* set if we are sending a memory map to gdb
 * via qXfer:memory-map:read packet */
/* enabled by default*/
static int gdb_use_memory_map = 1;
/* enabled by default*/
static int gdb_flash_program = 1;

/* if set, data aborts cause an error to be reported in memory read packets
 * see the code in gdb_read_memory_packet() for further explanations.
 * Disabled by default.
 */
static int gdb_report_data_abort;
/* If set, errors when accessing registers are reported to gdb. Disabled by
 * default. */
static int gdb_report_register_access_error;

/* set if we are sending target descriptions to gdb
 * via qXfer:features:read packet */
/* enabled by default */
static int gdb_use_target_description = 1;

/* current processing free-run type, used by file-I/O */
static char gdb_running_type;

static int gdb_last_signal(struct target *target)
{
        switch (target->debug_reason) {
                case DBG_REASON_DBGRQ:
                        return 0x2;             /* SIGINT */
                case DBG_REASON_BREAKPOINT:
                case DBG_REASON_WATCHPOINT:
                case DBG_REASON_WPTANDBKPT:
                        return 0x05;    /* SIGTRAP */
                case DBG_REASON_SINGLESTEP:
                        return 0x05;    /* SIGTRAP */
                case DBG_REASON_NOTHALTED:
                        return 0x0;             /* no signal... shouldn't happen */
                default:
                        LOG_USER("undefined debug reason %d - target needs reset",
                                        target->debug_reason);
                        return 0x0;
        }
}

static int check_pending(struct connection *connection,
                int timeout_s, int *got_data)
{
        /* a non-blocking socket will block if there is 0 bytes available on the socket,
         * but return with as many bytes as are available immediately
         */
        struct timeval tv;
        fd_set read_fds;
        struct gdb_connection *gdb_con = connection->priv;
        int t;
        if (got_data == NULL)
                got_data = &t;
        *got_data = 0;

        if (gdb_con->buf_cnt > 0) {
                *got_data = 1;
                return ERROR_OK;
        }

        FD_ZERO(&read_fds);
        FD_SET(connection->fd, &read_fds);

        tv.tv_sec = timeout_s;
        tv.tv_usec = 0;
        if (socket_select(connection->fd + 1, &read_fds, NULL, NULL, &tv) == 0) {
                /* This can typically be because a "monitor" command took too long
                 * before printing any progress messages
                 */
                if (timeout_s > 0)
                        return ERROR_GDB_TIMEOUT;
                else
                        return ERROR_OK;
        }
        *got_data = FD_ISSET(connection->fd, &read_fds) != 0;
        return ERROR_OK;
}

static int gdb_get_char_inner(struct connection *connection, int *next_char)
{
        struct gdb_connection *gdb_con = connection->priv;
        int retval = ERROR_OK;

#ifdef _DEBUG_GDB_IO_
        char *debug_buffer;
#endif
        for (;; ) {
                if (connection->service->type != CONNECTION_TCP)
                        gdb_con->buf_cnt = read(connection->fd, gdb_con->buffer, GDB_BUFFER_SIZE);
                else {
                        retval = check_pending(connection, 1, NULL);
                        if (retval != ERROR_OK)
                                return retval;
                        gdb_con->buf_cnt = read_socket(connection->fd,
                                        gdb_con->buffer,
                                        GDB_BUFFER_SIZE);
                }

                if (gdb_con->buf_cnt > 0)
                        break;
                if (gdb_con->buf_cnt == 0) {
                        gdb_con->closed = true;
                        return ERROR_SERVER_REMOTE_CLOSED;
                }

#ifdef _WIN32
                errno = WSAGetLastError();

                switch (errno) {
                        case WSAEWOULDBLOCK:
                                usleep(1000);
                                break;
                        case WSAECONNABORTED:
                                gdb_con->closed = true;
                                return ERROR_SERVER_REMOTE_CLOSED;
                        case WSAECONNRESET:
                                gdb_con->closed = true;
                                return ERROR_SERVER_REMOTE_CLOSED;
                        default:
                                LOG_ERROR("read: %d", errno);
                                exit(-1);
                }
#else
                switch (errno) {
                        case EAGAIN:
                                usleep(1000);
                                break;
                        case ECONNABORTED:
                                gdb_con->closed = true;
                                return ERROR_SERVER_REMOTE_CLOSED;
                        case ECONNRESET:
                                gdb_con->closed = true;
                                return ERROR_SERVER_REMOTE_CLOSED;
                        default:
                                LOG_ERROR("read: %s", strerror(errno));
                                gdb_con->closed = true;
                                return ERROR_SERVER_REMOTE_CLOSED;
                }
#endif
        }

#ifdef _DEBUG_GDB_IO_
        debug_buffer = strndup(gdb_con->buffer, gdb_con->buf_cnt);
        LOG_DEBUG("received '%s'", debug_buffer);
        free(debug_buffer);
#endif

        gdb_con->buf_p = gdb_con->buffer;
        gdb_con->buf_cnt--;
        *next_char = *(gdb_con->buf_p++);
        if (gdb_con->buf_cnt > 0)
                connection->input_pending = 1;
        else
                connection->input_pending = 0;
#ifdef _DEBUG_GDB_IO_
        LOG_DEBUG("returned char '%c' (0x%2.2x)", *next_char, *next_char);
#endif

        return retval;
}

/**
 * The cool thing about this fn is that it allows buf_p and buf_cnt to be
 * held in registers in the inner loop.
 *
 * For small caches and embedded systems this is important!
 */
static inline int gdb_get_char_fast(struct connection *connection,
                int *next_char, char **buf_p, int *buf_cnt)
{
        int retval = ERROR_OK;

        if ((*buf_cnt)-- > 0) {
                *next_char = **buf_p;
                (*buf_p)++;
                if (*buf_cnt > 0)
                        connection->input_pending = 1;
                else
                        connection->input_pending = 0;

#ifdef _DEBUG_GDB_IO_
                LOG_DEBUG("returned char '%c' (0x%2.2x)", *next_char, *next_char);
#endif

                return ERROR_OK;
        }

        struct gdb_connection *gdb_con = connection->priv;
        gdb_con->buf_p = *buf_p;
        gdb_con->buf_cnt = *buf_cnt;
        retval = gdb_get_char_inner(connection, next_char);
        *buf_p = gdb_con->buf_p;
        *buf_cnt = gdb_con->buf_cnt;

        return retval;
}

static int gdb_get_char(struct connection *connection, int *next_char)
{
        struct gdb_connection *gdb_con = connection->priv;
        return gdb_get_char_fast(connection, next_char, &gdb_con->buf_p, &gdb_con->buf_cnt);
}

static int gdb_putback_char(struct connection *connection, int last_char)
{
        struct gdb_connection *gdb_con = connection->priv;

        if (gdb_con->buf_p > gdb_con->buffer) {
                *(--gdb_con->buf_p) = last_char;
                gdb_con->buf_cnt++;
        } else
                LOG_ERROR("BUG: couldn't put character back");

        return ERROR_OK;
}

/* The only way we can detect that the socket is closed is the first time
 * we write to it, we will fail. Subsequent write operations will
 * succeed. Shudder! */
static int gdb_write(struct connection *connection, void *data, int len)
{
        struct gdb_connection *gdb_con = connection->priv;
        if (gdb_con->closed)
                return ERROR_SERVER_REMOTE_CLOSED;

        if (connection_write(connection, data, len) == len)
                return ERROR_OK;
        gdb_con->closed = true;
        return ERROR_SERVER_REMOTE_CLOSED;
}

static int gdb_put_packet_inner(struct connection *connection,
                char *buffer, int len)
{
        int i;
        unsigned char my_checksum = 0;
#ifdef _DEBUG_GDB_IO_
        char *debug_buffer;
#endif
        int reply;
        int retval;
        struct gdb_connection *gdb_con = connection->priv;

        for (i = 0; i < len; i++)
                my_checksum += buffer[i];

#ifdef _DEBUG_GDB_IO_
        /*
         * At this point we should have nothing in the input queue from GDB,
         * however sometimes '-' is sent even though we've already received
         * an ACK (+) for everything we've sent off.
         */
        int gotdata;
        for (;; ) {
                retval = check_pending(connection, 0, &gotdata);
                if (retval != ERROR_OK)
                        return retval;
                if (!gotdata)
                        break;
                retval = gdb_get_char(connection, &reply);
                if (retval != ERROR_OK)
                        return retval;
                if (reply == '$') {
                        /* fix a problem with some IAR tools */
                        gdb_putback_char(connection, reply);
                        LOG_DEBUG("Unexpected start of new packet");
                        break;
                }

                LOG_WARNING("Discard unexpected char %c", reply);
        }
#endif

        while (1) {
#ifdef _DEBUG_GDB_IO_
                debug_buffer = strndup(buffer, len);
                LOG_DEBUG("sending packet '$%s#%2.2x'", debug_buffer, my_checksum);
                free(debug_buffer);
#endif

                char local_buffer[1024];
                local_buffer[0] = '$';
                if ((size_t)len + 4 <= sizeof(local_buffer)) {
                        /* performance gain on smaller packets by only a single call to gdb_write() */
                        memcpy(local_buffer + 1, buffer, len++);
                        len += snprintf(local_buffer + len, sizeof(local_buffer) - len, "#%02x", my_checksum);
                        retval = gdb_write(connection, local_buffer, len);
                        if (retval != ERROR_OK)
                                return retval;
                } else {
                        /* larger packets are transmitted directly from caller supplied buffer
                         * by several calls to gdb_write() to avoid dynamic allocation */
                        snprintf(local_buffer + 1, sizeof(local_buffer) - 1, "#%02x", my_checksum);
                        retval = gdb_write(connection, local_buffer, 1);
                        if (retval != ERROR_OK)
                                return retval;
                        retval = gdb_write(connection, buffer, len);
                        if (retval != ERROR_OK)
                                return retval;
                        retval = gdb_write(connection, local_buffer + 1, 3);
                        if (retval != ERROR_OK)
                                return retval;
                }

                if (gdb_con->noack_mode)
                        break;

                retval = gdb_get_char(connection, &reply);
                if (retval != ERROR_OK)
                        return retval;

                if (reply == '+')
                        break;
                else if (reply == '-') {
                        /* Stop sending output packets for now */
                        log_remove_callback(gdb_log_callback, connection);
                        LOG_WARNING("negative reply, retrying");
                } else if (reply == 0x3) {
                        gdb_con->ctrl_c = 1;
                        retval = gdb_get_char(connection, &reply);
                        if (retval != ERROR_OK)
                                return retval;
                        if (reply == '+')
                                break;
                        else if (reply == '-') {
                                /* Stop sending output packets for now */
                                log_remove_callback(gdb_log_callback, connection);
                                LOG_WARNING("negative reply, retrying");
                        } else if (reply == '$') {
                                LOG_ERROR("GDB missing ack(1) - assumed good");
                                gdb_putback_char(connection, reply);
                                return ERROR_OK;
                        } else {
                                LOG_ERROR("unknown character(1) 0x%2.2x in reply, dropping connection", reply);
                                gdb_con->closed = true;
                                return ERROR_SERVER_REMOTE_CLOSED;
                        }
                } else if (reply == '$') {
                        LOG_ERROR("GDB missing ack(2) - assumed good");
                        gdb_putback_char(connection, reply);
                        return ERROR_OK;
                } else {
                        LOG_ERROR("unknown character(2) 0x%2.2x in reply, dropping connection",
                                reply);
                        gdb_con->closed = true;
                        return ERROR_SERVER_REMOTE_CLOSED;
                }
        }
        if (gdb_con->closed)
                return ERROR_SERVER_REMOTE_CLOSED;

        return ERROR_OK;
}

int gdb_put_packet(struct connection *connection, char *buffer, int len)
{
        struct gdb_connection *gdb_con = connection->priv;
        gdb_con->busy = true;
        int retval = gdb_put_packet_inner(connection, buffer, len);
        gdb_con->busy = false;

        /* we sent some data, reset timer for keep alive messages */
        kept_alive();

        return retval;
}

static inline int fetch_packet(struct connection *connection,
                int *checksum_ok, int noack, int *len, char *buffer)
{
        unsigned char my_checksum = 0;
        char checksum[3];
        int character;
        int retval = ERROR_OK;

        struct gdb_connection *gdb_con = connection->priv;
        my_checksum = 0;
        int count = 0;
        count = 0;

        /* move this over into local variables to use registers and give the
         * more freedom to optimize */
        char *buf_p = gdb_con->buf_p;
        int buf_cnt = gdb_con->buf_cnt;

        for (;; ) {
                /* The common case is that we have an entire packet with no escape chars.
                 * We need to leave at least 2 bytes in the buffer to have
                 * gdb_get_char() update various bits and bobs correctly.
                 */
                if ((buf_cnt > 2) && ((buf_cnt + count) < *len)) {
                        /* The compiler will struggle a bit with constant propagation and
                         * aliasing, so we help it by showing that these values do not
                         * change inside the loop
                         */
                        int i;
                        char *buf = buf_p;
                        int run = buf_cnt - 2;
                        i = 0;
                        int done = 0;
                        while (i < run) {
                                character = *buf++;
                                i++;
                                if (character == '#') {
                                        /* Danger! character can be '#' when esc is
                                         * used so we need an explicit boolean for done here. */
                                        done = 1;
                                        break;
                                }

                                if (character == '}') {
                                        /* data transmitted in binary mode (X packet)
                                         * uses 0x7d as escape character */
                                        my_checksum += character & 0xff;
                                        character = *buf++;
                                        i++;
                                        my_checksum += character & 0xff;
                                        buffer[count++] = (character ^ 0x20) & 0xff;
                                } else {
                                        my_checksum += character & 0xff;
                                        buffer[count++] = character & 0xff;
                                }
                        }
                        buf_p += i;
                        buf_cnt -= i;
                        if (done)
                                break;
                }
                if (count > *len) {
                        LOG_ERROR("packet buffer too small");
                        retval = ERROR_GDB_BUFFER_TOO_SMALL;
                        break;
                }

                retval = gdb_get_char_fast(connection, &character, &buf_p, &buf_cnt);
                if (retval != ERROR_OK)
                        break;

                if (character == '#')
                        break;

                if (character == '}') {
                        /* data transmitted in binary mode (X packet)
                         * uses 0x7d as escape character */
                        my_checksum += character & 0xff;

                        retval = gdb_get_char_fast(connection, &character, &buf_p, &buf_cnt);
                        if (retval != ERROR_OK)
                                break;

                        my_checksum += character & 0xff;
                        buffer[count++] = (character ^ 0x20) & 0xff;
                } else {
                        my_checksum += character & 0xff;
                        buffer[count++] = character & 0xff;
                }
        }

        gdb_con->buf_p = buf_p;
        gdb_con->buf_cnt = buf_cnt;

        if (retval != ERROR_OK)
                return retval;

        *len = count;

        retval = gdb_get_char(connection, &character);
        if (retval != ERROR_OK)
                return retval;
        checksum[0] = character;
        retval = gdb_get_char(connection, &character);
        if (retval != ERROR_OK)
                return retval;
        checksum[1] = character;
        checksum[2] = 0;

        if (!noack)
                *checksum_ok = (my_checksum == strtoul(checksum, NULL, 16));

        return ERROR_OK;
}

static int gdb_get_packet_inner(struct connection *connection,
                char *buffer, int *len)
{
        int character;
        int retval;
        struct gdb_connection *gdb_con = connection->priv;

        while (1) {
                do {
                        retval = gdb_get_char(connection, &character);
                        if (retval != ERROR_OK)
                                return retval;

#ifdef _DEBUG_GDB_IO_
                        LOG_DEBUG("character: '%c'", character);
#endif

                        switch (character) {
                                case '$':
                                        break;
                                case '+':
                                        /* According to the GDB documentation
                                         * (https://sourceware.org/gdb/onlinedocs/gdb/Packet-Acknowledgment.html):
                                         * "gdb sends a final `+` acknowledgment of the stub's `OK`
                                         * response, which can be safely ignored by the stub."
                                         * However OpenOCD server already is in noack mode at this
                                         * point and instead of ignoring this it was emitting a
                                         * warning. This code makes server ignore the first ACK
                                         * that will be received after going into noack mode,
                                         * warning only about subsequent ACK's. */
                                        if (gdb_con->noack_mode > 1) {
                                                LOG_WARNING("acknowledgment received, but no packet pending");
                                        } else if (gdb_con->noack_mode) {
                                                LOG_DEBUG("Received first acknowledgment after entering noack mode. Ignoring it.");
                                                gdb_con->noack_mode = 2;
                                        }
                                        break;
                                case '-':
                                        LOG_WARNING("negative acknowledgment, but no packet pending");
                                        break;
                                case 0x3:
                                        gdb_con->ctrl_c = 1;
                                        *len = 0;
                                        return ERROR_OK;
                                default:
                                        LOG_WARNING("ignoring character 0x%x", character);
                                        break;
                        }
                } while (character != '$');

                int checksum_ok = 0;
                /* explicit code expansion here to get faster inlined code in -O3 by not
                 * calculating checksum */
                if (gdb_con->noack_mode) {
                        retval = fetch_packet(connection, &checksum_ok, 1, len, buffer);
                        if (retval != ERROR_OK)
                                return retval;
                } else {
                        retval = fetch_packet(connection, &checksum_ok, 0, len, buffer);
                        if (retval != ERROR_OK)
                                return retval;
                }

                if (gdb_con->noack_mode) {
                        /* checksum is not checked in noack mode */
                        break;
                }
                if (checksum_ok) {
                        retval = gdb_write(connection, "+", 1);
                        if (retval != ERROR_OK)
                                return retval;
                        break;
                }
        }
        if (gdb_con->closed)
                return ERROR_SERVER_REMOTE_CLOSED;

        return ERROR_OK;
}

static int gdb_get_packet(struct connection *connection, char *buffer, int *len)
{
        struct gdb_connection *gdb_con = connection->priv;
        gdb_con->busy = true;
        int retval = gdb_get_packet_inner(connection, buffer, len);
        gdb_con->busy = false;
        return retval;
}

static int gdb_output_con(struct connection *connection, const char *line)
{
        char *hex_buffer;
        int bin_size;

        bin_size = strlen(line);

        hex_buffer = malloc(bin_size * 2 + 2);
        if (hex_buffer == NULL)
                return ERROR_GDB_BUFFER_TOO_SMALL;

        hex_buffer[0] = 'O';
        size_t pkt_len = hexify(hex_buffer + 1, (const uint8_t *)line, bin_size,
                bin_size * 2 + 1);
        int retval = gdb_put_packet(connection, hex_buffer, pkt_len + 1);

        free(hex_buffer);
        return retval;
}

static int gdb_output(struct command_context *context, const char *line)
{
        /* this will be dumped to the log and also sent as an O packet if possible */
        LOG_USER_N("%s", line);
        return ERROR_OK;
}

static void gdb_signal_reply(struct target *target, struct connection *connection)
{
        struct gdb_connection *gdb_connection = connection->priv;
        char sig_reply[45];
        char stop_reason[20];
        char current_thread[25];
        int sig_reply_len;
        int signal_var;

        rtos_update_threads(target);

        if (target->debug_reason == DBG_REASON_EXIT) {
                sig_reply_len = snprintf(sig_reply, sizeof(sig_reply), "W00");
        } else {
                if (gdb_connection->ctrl_c) {
                        signal_var = 0x2;
                } else
                        signal_var = gdb_last_signal(target);

                stop_reason[0] = '\0';
                if (target->debug_reason == DBG_REASON_WATCHPOINT) {
                        enum watchpoint_rw hit_wp_type;
                        target_addr_t hit_wp_address;

                        if (watchpoint_hit(target, &hit_wp_type, &hit_wp_address) == ERROR_OK) {

                                switch (hit_wp_type) {
                                        case WPT_WRITE:
                                                snprintf(stop_reason, sizeof(stop_reason),
                                                                "watch:%08" TARGET_PRIxADDR ";", hit_wp_address);
                                                break;
                                        case WPT_READ:
                                                snprintf(stop_reason, sizeof(stop_reason),
                                                                "rwatch:%08" TARGET_PRIxADDR ";", hit_wp_address);
                                                break;
                                        case WPT_ACCESS:
                                                snprintf(stop_reason, sizeof(stop_reason),
                                                                "awatch:%08" TARGET_PRIxADDR ";", hit_wp_address);
                                                break;
                                        default:
                                                break;
                                }
                        }
                }

                current_thread[0] = '\0';
                if (target->rtos != NULL) {
                        struct target *ct;
                        snprintf(current_thread, sizeof(current_thread), "thread:%016" PRIx64 ";",
                                        target->rtos->current_thread);
                        target->rtos->current_threadid = target->rtos->current_thread;
                        target->rtos->gdb_target_for_threadid(connection, target->rtos->current_threadid, &ct);
                        if (!gdb_connection->ctrl_c)
                                signal_var = gdb_last_signal(ct);
                }

                sig_reply_len = snprintf(sig_reply, sizeof(sig_reply), "T%2.2x%s%s",
                                signal_var, stop_reason, current_thread);

                gdb_connection->ctrl_c = 0;
        }

        gdb_put_packet(connection, sig_reply, sig_reply_len);
        gdb_connection->frontend_state = TARGET_HALTED;
}

static void gdb_fileio_reply(struct target *target, struct connection *connection)
{
        struct gdb_connection *gdb_connection = connection->priv;
        char fileio_command[256];
        int command_len;
        bool program_exited = false;

        if (strcmp(target->fileio_info->identifier, "open") == 0)
                sprintf(fileio_command, "F%s,%" PRIx32 "/%" PRIx32 ",%" PRIx32 ",%" PRIx32, target->fileio_info->identifier,
                                target->fileio_info->param_1,
                                target->fileio_info->param_2,
                                target->fileio_info->param_3,
                                target->fileio_info->param_4);
        else if (strcmp(target->fileio_info->identifier, "close") == 0)
                sprintf(fileio_command, "F%s,%" PRIx32, target->fileio_info->identifier,
                                target->fileio_info->param_1);
        else if (strcmp(target->fileio_info->identifier, "read") == 0)
                sprintf(fileio_command, "F%s,%" PRIx32 ",%" PRIx32 ",%" PRIx32, target->fileio_info->identifier,
                                target->fileio_info->param_1,
                                target->fileio_info->param_2,
                                target->fileio_info->param_3);
        else if (strcmp(target->fileio_info->identifier, "write") == 0)
                sprintf(fileio_command, "F%s,%" PRIx32 ",%" PRIx32 ",%" PRIx32, target->fileio_info->identifier,
                                target->fileio_info->param_1,
                                target->fileio_info->param_2,
                                target->fileio_info->param_3);
        else if (strcmp(target->fileio_info->identifier, "lseek") == 0)
                sprintf(fileio_command, "F%s,%" PRIx32 ",%" PRIx32 ",%" PRIx32, target->fileio_info->identifier,
                                target->fileio_info->param_1,
                                target->fileio_info->param_2,
                                target->fileio_info->param_3);
        else if (strcmp(target->fileio_info->identifier, "rename") == 0)
                sprintf(fileio_command, "F%s,%" PRIx32 "/%" PRIx32 ",%" PRIx32 "/%" PRIx32, target->fileio_info->identifier,
                                target->fileio_info->param_1,
                                target->fileio_info->param_2,
                                target->fileio_info->param_3,
                                target->fileio_info->param_4);
        else if (strcmp(target->fileio_info->identifier, "unlink") == 0)
                sprintf(fileio_command, "F%s,%" PRIx32 "/%" PRIx32, target->fileio_info->identifier,
                                target->fileio_info->param_1,
                                target->fileio_info->param_2);
        else if (strcmp(target->fileio_info->identifier, "stat") == 0)
                sprintf(fileio_command, "F%s,%" PRIx32 "/%" PRIx32 ",%" PRIx32, target->fileio_info->identifier,
                                target->fileio_info->param_1,
                                target->fileio_info->param_2,
                                target->fileio_info->param_3);
        else if (strcmp(target->fileio_info->identifier, "fstat") == 0)
                sprintf(fileio_command, "F%s,%" PRIx32 ",%" PRIx32, target->fileio_info->identifier,
                                target->fileio_info->param_1,
                                target->fileio_info->param_2);
        else if (strcmp(target->fileio_info->identifier, "gettimeofday") == 0)
                sprintf(fileio_command, "F%s,%" PRIx32 ",%" PRIx32, target->fileio_info->identifier,
                                target->fileio_info->param_1,
                                target->fileio_info->param_2);
        else if (strcmp(target->fileio_info->identifier, "isatty") == 0)
                sprintf(fileio_command, "F%s,%" PRIx32, target->fileio_info->identifier,
                                target->fileio_info->param_1);
        else if (strcmp(target->fileio_info->identifier, "system") == 0)
                sprintf(fileio_command, "F%s,%" PRIx32 "/%" PRIx32, target->fileio_info->identifier,
                                target->fileio_info->param_1,
                                target->fileio_info->param_2);
        else if (strcmp(target->fileio_info->identifier, "exit") == 0) {
                /* If target hits exit syscall, report to GDB the program is terminated.
                 * In addition, let target run its own exit syscall handler. */
                program_exited = true;
                sprintf(fileio_command, "W%02" PRIx32, target->fileio_info->param_1);
        } else {
                LOG_DEBUG("Unknown syscall: %s", target->fileio_info->identifier);

                /* encounter unknown syscall, continue */
                gdb_connection->frontend_state = TARGET_RUNNING;
                target_resume(target, 1, 0x0, 0, 0);
                return;
        }

        command_len = strlen(fileio_command);
        gdb_put_packet(connection, fileio_command, command_len);

        if (program_exited) {
                /* Use target_resume() to let target run its own exit syscall handler. */
                gdb_connection->frontend_state = TARGET_RUNNING;
                target_resume(target, 1, 0x0, 0, 0);
        } else {
                gdb_connection->frontend_state = TARGET_HALTED;
                rtos_update_threads(target);
        }
}

static void gdb_frontend_halted(struct target *target, struct connection *connection)
{
        struct gdb_connection *gdb_connection = connection->priv;

        /* In the GDB protocol when we are stepping or continuing execution,
         * we have a lingering reply. Upon receiving a halted event
         * when we have that lingering packet, we reply to the original
         * step or continue packet.
         *
         * Executing monitor commands can bring the target in and
         * out of the running state so we'll see lots of TARGET_EVENT_XXX
         * that are to be ignored.
         */
        if (gdb_connection->frontend_state == TARGET_RUNNING) {
                /* stop forwarding log packets! */
                log_remove_callback(gdb_log_callback, connection);

                /* check fileio first */
                if (target_get_gdb_fileio_info(target, target->fileio_info) == ERROR_OK)
                        gdb_fileio_reply(target, connection);
                else
                        gdb_signal_reply(target, connection);
        }
}

static int gdb_target_callback_event_handler(struct target *target,
                enum target_event event, void *priv)
{
        int retval;
        struct connection *connection = priv;
        struct gdb_service *gdb_service = connection->service->priv;

        if (gdb_service->target != target)
                return ERROR_OK;

        switch (event) {
                case TARGET_EVENT_GDB_HALT:
                        gdb_frontend_halted(target, connection);
                        break;
                case TARGET_EVENT_HALTED:
                        target_call_event_callbacks(target, TARGET_EVENT_GDB_END);
                        break;
                case TARGET_EVENT_GDB_FLASH_ERASE_START:
                        retval = jtag_execute_queue();
                        if (retval != ERROR_OK)
                                return retval;
                        break;
                default:
                        break;
        }

        return ERROR_OK;
}

static int gdb_new_connection(struct connection *connection)
{
        struct gdb_connection *gdb_connection = malloc(sizeof(struct gdb_connection));
        struct target *target;
        int retval;
        int initial_ack;

        target = get_target_from_connection(connection);
        connection->priv = gdb_connection;

        /* initialize gdb connection information */
        gdb_connection->buf_p = gdb_connection->buffer;
        gdb_connection->buf_cnt = 0;
        gdb_connection->ctrl_c = 0;
        gdb_connection->frontend_state = TARGET_HALTED;
        gdb_connection->vflash_image = NULL;
        gdb_connection->closed = false;
        gdb_connection->busy = false;
        gdb_connection->noack_mode = 0;
        gdb_connection->sync = false;
        gdb_connection->mem_write_error = false;
        gdb_connection->attached = true;
        gdb_connection->target_desc.tdesc = NULL;
        gdb_connection->target_desc.tdesc_length = 0;
        gdb_connection->thread_list = NULL;

        /* send ACK to GDB for debug request */
        gdb_write(connection, "+", 1);

        /* output goes through gdb connection */
        command_set_output_handler(connection->cmd_ctx, gdb_output, connection);

        /* we must remove all breakpoints registered to the target as a previous
         * GDB session could leave dangling breakpoints if e.g. communication
         * timed out.
         */
        breakpoint_clear_target(target);
        watchpoint_clear_target(target);

        if (target->rtos) {
                /* clean previous rtos session if supported*/
                if (target->rtos->type->clean)
                        target->rtos->type->clean(target);

                /* update threads */
                rtos_update_threads(target);
        }

        /* remove the initial ACK from the incoming buffer */
        retval = gdb_get_char(connection, &initial_ack);
        if (retval != ERROR_OK)
                return retval;

        /* FIX!!!??? would we actually ever receive a + here???
         * Not observed.
         */
        if (initial_ack != '+')
                gdb_putback_char(connection, initial_ack);
        target_call_event_callbacks(target, TARGET_EVENT_GDB_ATTACH);

        if (gdb_use_memory_map) {
                /* Connect must fail if the memory map can't be set up correctly.
                 *
                 * This will cause an auto_probe to be invoked, which is either
                 * a no-op or it will fail when the target isn't ready(e.g. not halted).
                 */
                int i;
                for (i = 0; i < flash_get_bank_count(); i++) {
                        struct flash_bank *p;
                        p = get_flash_bank_by_num_noprobe(i);
                        if (p->target != target)
                                continue;
                        retval = get_flash_bank_by_num(i, &p);
                        if (retval != ERROR_OK) {
                                LOG_ERROR("Connect failed. Consider setting up a gdb-attach event for the target " \
                                                "to prepare target for GDB connect, or use 'gdb_memory_map disable'.");
                                return retval;
                        }
                }
        }

        gdb_actual_connections++;
        log_printf_lf(all_targets->next != NULL ? LOG_LVL_INFO : LOG_LVL_DEBUG,
                        __FILE__, __LINE__, __func__,
                        "New GDB Connection: %d, Target %s, state: %s",
                        gdb_actual_connections,
                        target_name(target),
                        target_state_name(target));

        /* DANGER! If we fail subsequently, we must remove this handler,
         * otherwise we occasionally see crashes as the timer can invoke the
         * callback fn.
         *
         * register callback to be informed about target events */
        target_register_event_callback(gdb_target_callback_event_handler, connection);

        return ERROR_OK;
}

static int gdb_connection_closed(struct connection *connection)
{
        struct target *target;
        struct gdb_connection *gdb_connection = connection->priv;

        target = get_target_from_connection(connection);

        /* we're done forwarding messages. Tear down callback before
         * cleaning up connection.
         */
        log_remove_callback(gdb_log_callback, connection);

        gdb_actual_connections--;
        LOG_DEBUG("GDB Close, Target: %s, state: %s, gdb_actual_connections=%d",
                target_name(target),
                target_state_name(target),
                gdb_actual_connections);

        /* see if an image built with vFlash commands is left */
        if (gdb_connection->vflash_image) {
                image_close(gdb_connection->vflash_image);
                free(gdb_connection->vflash_image);
                gdb_connection->vflash_image = NULL;
        }

        /* if this connection registered a debug-message receiver delete it */
        delete_debug_msg_receiver(connection->cmd_ctx, target);

        if (connection->priv) {
                free(connection->priv);
                connection->priv = NULL;
        } else
                LOG_ERROR("BUG: connection->priv == NULL");

        target_unregister_event_callback(gdb_target_callback_event_handler, connection);

        target_call_event_callbacks(target, TARGET_EVENT_GDB_END);

        target_call_event_callbacks(target, TARGET_EVENT_GDB_DETACH);

        return ERROR_OK;
}

static void gdb_send_error(struct connection *connection, uint8_t the_error)
{
        char err[4];
        snprintf(err, 4, "E%2.2X", the_error);
        gdb_put_packet(connection, err, 3);
}

static int gdb_last_signal_packet(struct connection *connection,
                char const *packet, int packet_size)
{
        struct target *target = get_target_from_connection(connection);
        struct gdb_connection *gdb_con = connection->priv;
        char sig_reply[4];
        int signal_var;

        if (!gdb_con->attached) {
                /* if we are here we have received a kill packet
                 * reply W stop reply otherwise gdb gets very unhappy */
                gdb_put_packet(connection, "W00", 3);
                return ERROR_OK;
        }

        signal_var = gdb_last_signal(target);

        snprintf(sig_reply, 4, "S%2.2x", signal_var);
        gdb_put_packet(connection, sig_reply, 3);

        return ERROR_OK;
}

static inline int gdb_reg_pos(struct target *target, int pos, int len)
{
        if (target->endianness == TARGET_LITTLE_ENDIAN)
                return pos;
        else
                return len - 1 - pos;
}

/* Convert register to string of bytes. NB! The # of bits in the
 * register might be non-divisible by 8(a byte), in which
 * case an entire byte is shown.
 *
 * NB! the format on the wire is the target endianness
 *
 * The format of reg->value is little endian
 *
 */
static void gdb_str_to_target(struct target *target,
                char *tstr, struct reg *reg)
{
        int i;

        uint8_t *buf;
        int buf_len;
        buf = reg->value;
        buf_len = DIV_ROUND_UP(reg->size, 8);

        for (i = 0; i < buf_len; i++) {
                int j = gdb_reg_pos(target, i, buf_len);
                tstr += sprintf(tstr, "%02x", buf[j]);
        }
}

/* copy over in register buffer */
static void gdb_target_to_reg(struct target *target,
                char const *tstr, int str_len, uint8_t *bin)
{
        if (str_len % 2) {
                LOG_ERROR("BUG: gdb value with uneven number of characters encountered");
                exit(-1);
        }

        int i;
        for (i = 0; i < str_len; i += 2) {
                unsigned t;
                if (sscanf(tstr + i, "%02x", &t) != 1) {
                        LOG_ERROR("BUG: unable to convert register value");
                        exit(-1);
                }

                int j = gdb_reg_pos(target, i/2, str_len/2);
                bin[j] = t;
        }
}

static int gdb_get_registers_packet(struct connection *connection,
                char const *packet, int packet_size)
{
        struct target *target = get_target_from_connection(connection);
        struct reg **reg_list;
        int reg_list_size;
        int retval;
        int reg_packet_size = 0;
        char *reg_packet;
        char *reg_packet_p;
        int i;

#ifdef _DEBUG_GDB_IO_
        LOG_DEBUG("-");
#endif

        if ((target->rtos != NULL) && (ERROR_OK == rtos_get_gdb_reg_list(connection)))
                return ERROR_OK;

        retval = target_get_gdb_reg_list(target, &reg_list, &reg_list_size,
                        REG_CLASS_GENERAL);
        if (retval != ERROR_OK)
                return gdb_error(connection, retval);

        for (i = 0; i < reg_list_size; i++)
                reg_packet_size += DIV_ROUND_UP(reg_list[i]->size, 8) * 2;

        assert(reg_packet_size > 0);

        reg_packet = malloc(reg_packet_size + 1); /* plus one for string termination null */
        if (reg_packet == NULL)
                return ERROR_FAIL;

        reg_packet_p = reg_packet;

        for (i = 0; i < reg_list_size; i++) {
                if (!reg_list[i]->valid) {
                        retval = reg_list[i]->type->get(reg_list[i]);
                        if (retval != ERROR_OK && gdb_report_register_access_error) {
                                LOG_DEBUG("Couldn't get register %s.", reg_list[i]->name);
                                free(reg_packet);
                                free(reg_list);
                                return gdb_error(connection, retval);
                        }
                }
                gdb_str_to_target(target, reg_packet_p, reg_list[i]);
                reg_packet_p += DIV_ROUND_UP(reg_list[i]->size, 8) * 2;
        }

#ifdef _DEBUG_GDB_IO_
        {
                char *reg_packet_p_debug;
                reg_packet_p_debug = strndup(reg_packet, reg_packet_size);
                LOG_DEBUG("reg_packet: %s", reg_packet_p_debug);
                free(reg_packet_p_debug);
        }
#endif

        gdb_put_packet(connection, reg_packet, reg_packet_size);
        free(reg_packet);

        free(reg_list);

        return ERROR_OK;
}

static int gdb_set_registers_packet(struct connection *connection,
                char const *packet, int packet_size)
{
        struct target *target = get_target_from_connection(connection);
        int i;
        struct reg **reg_list;
        int reg_list_size;
        int retval;
        char const *packet_p;

#ifdef _DEBUG_GDB_IO_
        LOG_DEBUG("-");
#endif

        /* skip command character */
        packet++;
        packet_size--;

        if (packet_size % 2) {
                LOG_WARNING("GDB set_registers packet with uneven characters received, dropping connection");
                return ERROR_SERVER_REMOTE_CLOSED;
        }

        retval = target_get_gdb_reg_list(target, &reg_list, &reg_list_size,
                        REG_CLASS_GENERAL);
        if (retval != ERROR_OK)
                return gdb_error(connection, retval);

        packet_p = packet;
        for (i = 0; i < reg_list_size; i++) {
                uint8_t *bin_buf;
                int chars = (DIV_ROUND_UP(reg_list[i]->size, 8) * 2);

                if (packet_p + chars > packet + packet_size)
                        LOG_ERROR("BUG: register packet is too small for registers");

                bin_buf = malloc(DIV_ROUND_UP(reg_list[i]->size, 8));
                gdb_target_to_reg(target, packet_p, chars, bin_buf);

                retval = reg_list[i]->type->set(reg_list[i], bin_buf);
                if (retval != ERROR_OK && gdb_report_register_access_error) {
                        LOG_DEBUG("Couldn't set register %s.", reg_list[i]->name);
                        free(reg_list);
                        free(bin_buf);
                        return gdb_error(connection, retval);
                }

                /* advance packet pointer */
                packet_p += chars;

                free(bin_buf);
        }

        /* free struct reg *reg_list[] array allocated by get_gdb_reg_list */
        free(reg_list);

        gdb_put_packet(connection, "OK", 2);

        return ERROR_OK;
}

static int gdb_get_register_packet(struct connection *connection,
        char const *packet, int packet_size)
{
        struct target *target = get_target_from_connection(connection);
        char *reg_packet;
        int reg_num = strtoul(packet + 1, NULL, 16);
        struct reg **reg_list;
        int reg_list_size;
        int retval;

#ifdef _DEBUG_GDB_IO_
        LOG_DEBUG("-");
#endif

        retval = target_get_gdb_reg_list(target, &reg_list, &reg_list_size,
                        REG_CLASS_ALL);
        if (retval != ERROR_OK)
                return gdb_error(connection, retval);

        if (reg_list_size <= reg_num) {
                LOG_ERROR("gdb requested a non-existing register");
                return ERROR_SERVER_REMOTE_CLOSED;
        }

        if (!reg_list[reg_num]->valid) {
                retval = reg_list[reg_num]->type->get(reg_list[reg_num]);
                if (retval != ERROR_OK && gdb_report_register_access_error) {
                        LOG_DEBUG("Couldn't get register %s.", reg_list[reg_num]->name);
                        free(reg_list);
                        return gdb_error(connection, retval);
                }
        }

        reg_packet = malloc(DIV_ROUND_UP(reg_list[reg_num]->size, 8) * 2 + 1); /* plus one for string termination null */

        gdb_str_to_target(target, reg_packet, reg_list[reg_num]);

        gdb_put_packet(connection, reg_packet, DIV_ROUND_UP(reg_list[reg_num]->size, 8) * 2);

        free(reg_list);
        free(reg_packet);

        return ERROR_OK;
}

static int gdb_set_register_packet(struct connection *connection,
        char const *packet, int packet_size)
{
        struct target *target = get_target_from_connection(connection);
        char *separator;
        uint8_t *bin_buf;
        int reg_num = strtoul(packet + 1, &separator, 16);
        struct reg **reg_list;
        int reg_list_size;
        int retval;

        LOG_DEBUG("-");

        retval = target_get_gdb_reg_list(target, &reg_list, &reg_list_size,
                        REG_CLASS_ALL);
        if (retval != ERROR_OK)
                return gdb_error(connection, retval);

        if (reg_list_size <= reg_num) {
                LOG_ERROR("gdb requested a non-existing register");
                return ERROR_SERVER_REMOTE_CLOSED;
        }

        if (*separator != '=') {
                LOG_ERROR("GDB 'set register packet', but no '=' following the register number");
                return ERROR_SERVER_REMOTE_CLOSED;
        }

        /* convert from GDB-string (target-endian) to hex-string (big-endian) */
        bin_buf = malloc(DIV_ROUND_UP(reg_list[reg_num]->size, 8));
        int chars = (DIV_ROUND_UP(reg_list[reg_num]->size, 8) * 2);

        if ((unsigned int)chars != strlen(separator + 1)) {
                LOG_ERROR("gdb sent a packet with wrong register size");
                free(bin_buf);
                return ERROR_SERVER_REMOTE_CLOSED;
        }

        gdb_target_to_reg(target, separator + 1, chars, bin_buf);

        retval = reg_list[reg_num]->type->set(reg_list[reg_num], bin_buf);
        if (retval != ERROR_OK && gdb_report_register_access_error) {
                LOG_DEBUG("Couldn't set register %s.", reg_list[reg_num]->name);
                free(bin_buf);
                free(reg_list);
                return gdb_error(connection, retval);
        }

        gdb_put_packet(connection, "OK", 2);

        free(bin_buf);
        free(reg_list);

        return ERROR_OK;
}

/* No attempt is made to translate the "retval" to
 * GDB speak. This has to be done at the calling
 * site as no mapping really exists.
 */
static int gdb_error(struct connection *connection, int retval)
{
        LOG_DEBUG("Reporting %i to GDB as generic error", retval);
        gdb_send_error(connection, EFAULT);
        return ERROR_OK;
}

/* We don't have to worry about the default 2 second timeout for GDB packets,
 * because GDB breaks up large memory reads into smaller reads.
 *
 * 8191 bytes by the looks of it. Why 8191 bytes instead of 8192?????
 */
static int gdb_read_memory_packet(struct connection *connection,
                char const *packet, int packet_size)
{
        struct target *target = get_target_from_connection(connection);
        char *separator;
        uint64_t addr = 0;
        uint32_t len = 0;

        uint8_t *buffer;
        char *hex_buffer;

        int retval = ERROR_OK;

        /* skip command character */
        packet++;

        addr = strtoull(packet, &separator, 16);

        if (*separator != ',') {
                LOG_ERROR("incomplete read memory packet received, dropping connection");
                return ERROR_SERVER_REMOTE_CLOSED;
        }

        len = strtoul(separator + 1, NULL, 16);

        if (!len) {
                LOG_WARNING("invalid read memory packet received (len == 0)");
                gdb_put_packet(connection, NULL, 0);
                return ERROR_OK;
        }

        buffer = malloc(len);

        LOG_DEBUG("addr: 0x%16.16" PRIx64 ", len: 0x%8.8" PRIx32 "", addr, len);

        retval = target_read_buffer(target, addr, len, buffer);

        if ((retval != ERROR_OK) && !gdb_report_data_abort) {
                /* TODO : Here we have to lie and send back all zero's lest stack traces won't work.
                 * At some point this might be fixed in GDB, in which case this code can be removed.
                 *
                 * OpenOCD developers are acutely aware of this problem, but there is nothing
                 * gained by involving the user in this problem that hopefully will get resolved
                 * eventually
                 *
                 * http://sourceware.org/cgi-bin/gnatsweb.pl? \
                 * cmd = view%20audit-trail&database = gdb&pr = 2395
                 *
                 * For now, the default is to fix up things to make current GDB versions work.
                 * This can be overwritten using the gdb_report_data_abort <'enable'|'disable'> command.
                 */
                memset(buffer, 0, len);
                retval = ERROR_OK;
        }

        if (retval == ERROR_OK) {
                hex_buffer = malloc(len * 2 + 1);

                size_t pkt_len = hexify(hex_buffer, buffer, len, len * 2 + 1);

                gdb_put_packet(connection, hex_buffer, pkt_len);

                free(hex_buffer);
        } else
                retval = gdb_error(connection, retval);

        free(buffer);

        return retval;
}

static int gdb_write_memory_packet(struct connection *connection,
                char const *packet, int packet_size)
{
        struct target *target = get_target_from_connection(connection);
        char *separator;
        uint64_t addr = 0;
        uint32_t len = 0;

        uint8_t *buffer;
        int retval;

        /* skip command character */
        packet++;

        addr = strtoull(packet, &separator, 16);

        if (*separator != ',') {
                LOG_ERROR("incomplete write memory packet received, dropping connection");
                return ERROR_SERVER_REMOTE_CLOSED;
        }

        len = strtoul(separator + 1, &separator, 16);

        if (*(separator++) != ':') {
                LOG_ERROR("incomplete write memory packet received, dropping connection");
                return ERROR_SERVER_REMOTE_CLOSED;
        }

        buffer = malloc(len);

        LOG_DEBUG("addr: 0x%" PRIx64 ", len: 0x%8.8" PRIx32 "", addr, len);

        if (unhexify(buffer, separator, len) != len)
                LOG_ERROR("unable to decode memory packet");

        retval = target_write_buffer(target, addr, len, buffer);

        if (retval == ERROR_OK)
                gdb_put_packet(connection, "OK", 2);
        else
                retval = gdb_error(connection, retval);

        free(buffer);

        return retval;
}

static int gdb_write_memory_binary_packet(struct connection *connection,
                char const *packet, int packet_size)
{
        struct target *target = get_target_from_connection(connection);
        char *separator;
        uint64_t addr = 0;
        uint32_t len = 0;

        int retval = ERROR_OK;
        /* Packets larger than fast_limit bytes will be acknowledged instantly on
         * the assumption that we're in a download and it's important to go as fast
         * as possible. */
        uint32_t fast_limit = 8;

        /* skip command character */
        packet++;

        addr = strtoull(packet, &separator, 16);

        if (*separator != ',') {
                LOG_ERROR("incomplete write memory binary packet received, dropping connection");
                return ERROR_SERVER_REMOTE_CLOSED;
        }

        len = strtoul(separator + 1, &separator, 16);

        if (*(separator++) != ':') {
                LOG_ERROR("incomplete write memory binary packet received, dropping connection");
                return ERROR_SERVER_REMOTE_CLOSED;
        }

        struct gdb_connection *gdb_connection = connection->priv;

        if (gdb_connection->mem_write_error)
                retval = ERROR_FAIL;

        if (retval == ERROR_OK) {
                if (len >= fast_limit) {
                        /* By replying the packet *immediately* GDB will send us a new packet
                         * while we write the last one to the target.
                         * We only do this for larger writes, so that users who do something like:
                         * p *((int*)0xdeadbeef)=8675309
                         * will get immediate feedback that that write failed.
                         */
                        gdb_put_packet(connection, "OK", 2);
                }
        } else {
                retval = gdb_error(connection, retval);
                /* now that we have reported the memory write error, we can clear the condition */
                gdb_connection->mem_write_error = false;
                if (retval != ERROR_OK)
                        return retval;
        }

        if (len) {
                LOG_DEBUG("addr: 0x%" PRIx64 ", len: 0x%8.8" PRIx32 "", addr, len);

                retval = target_write_buffer(target, addr, len, (uint8_t *)separator);
                if (retval != ERROR_OK)
                        gdb_connection->mem_write_error = true;
        }

        if (len < fast_limit) {
                if (retval != ERROR_OK) {
                        gdb_error(connection, retval);
                        gdb_connection->mem_write_error = false;
                } else {
                        gdb_put_packet(connection, "OK", 2);
                }
        }

        return ERROR_OK;
}

static int gdb_step_continue_packet(struct connection *connection,
                char const *packet, int packet_size)
{
        struct target *target = get_target_from_connection(connection);
        int current = 0;
        uint64_t address = 0x0;
        int retval = ERROR_OK;

        LOG_DEBUG("-");

        if (packet_size > 1)
                address = strtoull(packet + 1, NULL, 16);
        else
                current = 1;

        gdb_running_type = packet[0];
        if (packet[0] == 'c') {
                LOG_DEBUG("continue");
                /* resume at current address, don't handle breakpoints, not debugging */
                retval = target_resume(target, current, address, 0, 0);
        } else if (packet[0] == 's') {
                LOG_DEBUG("step");
                /* step at current or address, don't handle breakpoints */
                retval = target_step(target, current, address, 0);
        }
        return retval;
}

static int gdb_breakpoint_watchpoint_packet(struct connection *connection,
                char const *packet, int packet_size)
{
        struct target *target = get_target_from_connection(connection);
        int type;
        enum breakpoint_type bp_type = BKPT_SOFT /* dummy init to avoid warning */;
        enum watchpoint_rw wp_type = WPT_READ /* dummy init to avoid warning */;
        uint64_t address;
        uint32_t size;
        char *separator;
        int retval;

        LOG_DEBUG("-");

        type = strtoul(packet + 1, &separator, 16);

        if (type == 0)  /* memory breakpoint */
                bp_type = BKPT_SOFT;
        else if (type == 1)     /* hardware breakpoint */
                bp_type = BKPT_HARD;
        else if (type == 2)     /* write watchpoint */
                wp_type = WPT_WRITE;
        else if (type == 3)     /* read watchpoint */
                wp_type = WPT_READ;
        else if (type == 4)     /* access watchpoint */
                wp_type = WPT_ACCESS;
        else {
                LOG_ERROR("invalid gdb watch/breakpoint type(%d), dropping connection", type);
                return ERROR_SERVER_REMOTE_CLOSED;
        }

        if (gdb_breakpoint_override && ((bp_type == BKPT_SOFT) || (bp_type == BKPT_HARD)))
                bp_type = gdb_breakpoint_override_type;

        if (*separator != ',') {
                LOG_ERROR("incomplete breakpoint/watchpoint packet received, dropping connection");
                return ERROR_SERVER_REMOTE_CLOSED;
        }

        address = strtoull(separator + 1, &separator, 16);

        if (*separator != ',') {
                LOG_ERROR("incomplete breakpoint/watchpoint packet received, dropping connection");
                return ERROR_SERVER_REMOTE_CLOSED;
        }

        size = strtoul(separator + 1, &separator, 16);

        switch (type) {
                case 0:
                case 1:
                        if (packet[0] == 'Z') {
                                retval = breakpoint_add(target, address, size, bp_type);
                                if (retval != ERROR_OK) {
                                        retval = gdb_error(connection, retval);
                                        if (retval != ERROR_OK)
                                                return retval;
                                } else
                                        gdb_put_packet(connection, "OK", 2);
                        } else {
                                breakpoint_remove(target, address);
                                gdb_put_packet(connection, "OK", 2);
                        }
                        break;
                case 2:
                case 3:
                case 4:
                {
                        if (packet[0] == 'Z') {
                                retval = watchpoint_add(target, address, size, wp_type, 0, 0xffffffffu);
                                if (retval != ERROR_OK) {
                                        retval = gdb_error(connection, retval);
                                        if (retval != ERROR_OK)
                                                return retval;
                                } else
                                        gdb_put_packet(connection, "OK", 2);
                        } else {
                                watchpoint_remove(target, address);
                                gdb_put_packet(connection, "OK", 2);
                        }
                        break;
                }
                default:
                        break;
        }

        return ERROR_OK;
}

/* print out a string and allocate more space as needed,
 * mainly used for XML at this point
 */
static void xml_printf(int *retval, char **xml, int *pos, int *size,
                const char *fmt, ...)
{
        if (*retval != ERROR_OK)
                return;
        int first = 1;

        for (;; ) {
                if ((*xml == NULL) || (!first)) {
                        /* start by 0 to exercise all the code paths.
                         * Need minimum 2 bytes to fit 1 char and 0 terminator. */

                        *size = *size * 2 + 2;
                        char *t = *xml;
                        *xml = realloc(*xml, *size);
                        if (*xml == NULL) {
                                if (t)
                                        free(t);
                                *retval = ERROR_SERVER_REMOTE_CLOSED;
                                return;
                        }
                }

                va_list ap;
                int ret;
                va_start(ap, fmt);
                ret = vsnprintf(*xml + *pos, *size - *pos, fmt, ap);
                va_end(ap);
                if ((ret > 0) && ((ret + 1) < *size - *pos)) {
                        *pos += ret;
                        return;
                }
                /* there was just enough or not enough space, allocate more. */
                first = 0;
        }
}

static int decode_xfer_read(char const *buf, char **annex, int *ofs, unsigned int *len)
{
        /* Locate the annex. */
        const char *annex_end = strchr(buf, ':');
        if (annex_end == NULL)
                return ERROR_FAIL;

        /* After the read marker and annex, qXfer looks like a
         * traditional 'm' packet. */
        char *separator;
        *ofs = strtoul(annex_end + 1, &separator, 16);

        if (*separator != ',')
                return ERROR_FAIL;

        *len = strtoul(separator + 1, NULL, 16);

        /* Extract the annex if needed */
        if (annex != NULL) {
                *annex = strndup(buf, annex_end - buf);
                if (*annex == NULL)
                        return ERROR_FAIL;
        }

        return ERROR_OK;
}

static int compare_bank(const void *a, const void *b)
{
        struct flash_bank *b1, *b2;
        b1 = *((struct flash_bank **)a);
        b2 = *((struct flash_bank **)b);

        if (b1->base == b2->base)
                return 0;
        else if (b1->base > b2->base)
                return 1;
        else
                return -1;
}

static int gdb_memory_map(struct connection *connection,
                char const *packet, int packet_size)
{
        /* We get away with only specifying flash here. Regions that are not
         * specified are treated as if we provided no memory map(if not we
         * could detect the holes and mark them as RAM).
         * Normally we only execute this code once, but no big deal if we
         * have to regenerate it a couple of times.
         */

        struct target *target = get_target_from_connection(connection);
        struct flash_bank *p;
        char *xml = NULL;
        int size = 0;
        int pos = 0;
        int retval = ERROR_OK;
        struct flash_bank **banks;
        int offset;
        int length;
        char *separator;
        uint32_t ram_start = 0;
        int i;
        int target_flash_banks = 0;

        /* skip command character */
        packet += 23;

        offset = strtoul(packet, &separator, 16);
        length = strtoul(separator + 1, &separator, 16);

        xml_printf(&retval, &xml, &pos, &size, "<memory-map>\n");

        /* Sort banks in ascending order.  We need to report non-flash
         * memory as ram (or rather read/write) by default for GDB, since
         * it has no concept of non-cacheable read/write memory (i/o etc).
         *
         * FIXME Most non-flash addresses are *NOT* RAM!  Don't lie.
         * Current versions of GDB assume unlisted addresses are RAM...
         */
        banks = malloc(sizeof(struct flash_bank *)*flash_get_bank_count());

        for (i = 0; i < flash_get_bank_count(); i++) {
                p = get_flash_bank_by_num_noprobe(i);
                if (p->target != target)
                        continue;
                retval = get_flash_bank_by_num(i, &p);
                if (retval != ERROR_OK) {
                        free(banks);
                        gdb_error(connection, retval);
                        return retval;
                }
                banks[target_flash_banks++] = p;
        }

        qsort(banks, target_flash_banks, sizeof(struct flash_bank *),
                compare_bank);

        for (i = 0; i < target_flash_banks; i++) {
                int j;
                unsigned sector_size = 0;
                uint32_t start;

                p = banks[i];
                start = p->base;

                if (ram_start < p->base)
                        xml_printf(&retval, &xml, &pos, &size,
                                "<memory type=\"ram\" start=\"0x%x\" "
                                "length=\"0x%x\"/>\n",
                                ram_start, p->base - ram_start);

                /* Report adjacent groups of same-size sectors.  So for
                 * example top boot CFI flash will list an initial region
                 * with several large sectors (maybe 128KB) and several
                 * smaller ones at the end (maybe 32KB).  STR7 will have
                 * regions with 8KB, 32KB, and 64KB sectors; etc.
                 */
                for (j = 0; j < p->num_sectors; j++) {
                        unsigned group_len;

                        /* Maybe start a new group of sectors. */
                        if (sector_size == 0) {
                                start = p->base + p->sectors[j].offset;
                                xml_printf(&retval, &xml, &pos, &size,
                                        "<memory type=\"flash\" "
                                        "start=\"0x%x\" ",
                                        start);
                                sector_size = p->sectors[j].size;
                        }

                        /* Does this finish a group of sectors?
                         * If not, continue an already-started group.
                         */
                        if (j == p->num_sectors - 1)
                                group_len = (p->base + p->size) - start;
                        else if (p->sectors[j + 1].size != sector_size)
                                group_len = p->base + p->sectors[j + 1].offset
                                        - start;
                        else
                                continue;

                        xml_printf(&retval, &xml, &pos, &size,
                                "length=\"0x%x\">\n"
                                "<property name=\"blocksize\">"
                                "0x%x</property>\n"
                                "</memory>\n",
                                group_len,
                                sector_size);
                        sector_size = 0;
                }

                ram_start = p->base + p->size;
        }

        if (ram_start != 0)
                xml_printf(&retval, &xml, &pos, &size,
                        "<memory type=\"ram\" start=\"0x%x\" "
                        "length=\"0x%x\"/>\n",
                        ram_start, 0-ram_start);
        /* ELSE a flash chip could be at the very end of the 32 bit address
         * space, in which case ram_start will be precisely 0
         */

        free(banks);
        banks = NULL;

        xml_printf(&retval, &xml, &pos, &size, "</memory-map>\n");

        if (retval != ERROR_OK) {
                gdb_error(connection, retval);
                return retval;
        }

        if (offset + length > pos)
                length = pos - offset;

        char *t = malloc(length + 1);
        t[0] = 'l';
        memcpy(t + 1, xml + offset, length);
        gdb_put_packet(connection, t, length + 1);

        free(t);
        free(xml);
        return ERROR_OK;
}

static const char *gdb_get_reg_type_name(enum reg_type type)
{
        switch (type) {
                case REG_TYPE_BOOL:
                        return "bool";
                case REG_TYPE_INT:
                        return "int";
                case REG_TYPE_INT8:
                        return "int8";
                case REG_TYPE_INT16:
                        return "int16";
                case REG_TYPE_INT32:
                        return "int32";
                case REG_TYPE_INT64:
                        return "int64";
                case REG_TYPE_INT128:
                        return "int128";
                case REG_TYPE_UINT:
                        return "uint";
                case REG_TYPE_UINT8:
                        return "uint8";
                case REG_TYPE_UINT16:
                        return "uint16";
                case REG_TYPE_UINT32:
                        return "uint32";
                case REG_TYPE_UINT64:
                        return "uint64";
                case REG_TYPE_UINT128:
                        return "uint128";
                case REG_TYPE_CODE_PTR:
                        return "code_ptr";
                case REG_TYPE_DATA_PTR:
                        return "data_ptr";
                case REG_TYPE_FLOAT:
                        return "float";
                case REG_TYPE_IEEE_SINGLE:
                        return "ieee_single";
                case REG_TYPE_IEEE_DOUBLE:
                        return "ieee_double";
                case REG_TYPE_ARCH_DEFINED:
                        return "int"; /* return arbitrary string to avoid compile warning. */
        }

        return "int"; /* "int" as default value */
}

static int lookup_add_arch_defined_types(char const **arch_defined_types_list[], const char *type_id,
                                        int *num_arch_defined_types)
{
        int tbl_sz = *num_arch_defined_types;

        if (type_id != NULL && (strcmp(type_id, ""))) {
                for (int j = 0; j < (tbl_sz + 1); j++) {
                        if (!((*arch_defined_types_list)[j])) {
                                (*arch_defined_types_list)[tbl_sz++] = type_id;
                                *arch_defined_types_list = realloc(*arch_defined_types_list,
                                                                sizeof(char *) * (tbl_sz + 1));
                                (*arch_defined_types_list)[tbl_sz] = NULL;
                                *num_arch_defined_types = tbl_sz;
                                return 1;
                        } else {
                                if (!strcmp((*arch_defined_types_list)[j], type_id))
                                        return 0;
                        }
                }
        }

        return -1;
}

static int gdb_generate_reg_type_description(struct target *target,
                char **tdesc, int *pos, int *size, struct reg_data_type *type,
                char const **arch_defined_types_list[], int * num_arch_defined_types)
{
        int retval = ERROR_OK;

        if (type->type_class == REG_TYPE_CLASS_VECTOR) {
                struct reg_data_type *data_type = type->reg_type_vector->type;
                if (data_type->type == REG_TYPE_ARCH_DEFINED) {
                        if (lookup_add_arch_defined_types(arch_defined_types_list, data_type->id,
                                                        num_arch_defined_types))
                                gdb_generate_reg_type_description(target, tdesc, pos, size, data_type,
                                                                arch_defined_types_list,
                                                                num_arch_defined_types);
                }
                /* <vector id="id" type="type" count="count"/> */
                xml_printf(&retval, tdesc, pos, size,
                                "<vector id=\"%s\" type=\"%s\" count=\"%d\"/>\n",
                                type->id, type->reg_type_vector->type->id,
                                type->reg_type_vector->count);

        } else if (type->type_class == REG_TYPE_CLASS_UNION) {
                struct reg_data_type_union_field *field;
                field = type->reg_type_union->fields;
                while (field != NULL) {
                        struct reg_data_type *data_type = field->type;
                        if (data_type->type == REG_TYPE_ARCH_DEFINED) {
                                if (lookup_add_arch_defined_types(arch_defined_types_list, data_type->id,
                                                                num_arch_defined_types))
                                        gdb_generate_reg_type_description(target, tdesc, pos, size, data_type,
                                                                        arch_defined_types_list,
                                                                        num_arch_defined_types);
                        }

                        field = field->next;
                }
                /* <union id="id">
                 *  <field name="name" type="type"/> ...
                 * </union> */
                xml_printf(&retval, tdesc, pos, size,
                                "<union id=\"%s\">\n",
                                type->id);

                field = type->reg_type_union->fields;
                while (field != NULL) {
                        xml_printf(&retval, tdesc, pos, size,
                                        "<field name=\"%s\" type=\"%s\"/>\n",
                                        field->name, field->type->id);

                        field = field->next;
                }

                xml_printf(&retval, tdesc, pos, size,
                                "</union>\n");

        } else if (type->type_class == REG_TYPE_CLASS_STRUCT) {
                struct reg_data_type_struct_field *field;
                field = type->reg_type_struct->fields;

                if (field->use_bitfields) {
                        /* <struct id="id" size="size">
                         *  <field name="name" start="start" end="end"/> ...
                         * </struct> */
                        xml_printf(&retval, tdesc, pos, size,
                                        "<struct id=\"%s\" size=\"%d\">\n",
                                        type->id, type->reg_type_struct->size);
                        while (field != NULL) {
                                xml_printf(&retval, tdesc, pos, size,
                                                "<field name=\"%s\" start=\"%d\" end=\"%d\" type=\"%s\" />\n",
                                                field->name, field->bitfield->start, field->bitfield->end,
                                                gdb_get_reg_type_name(field->bitfield->type));

                                field = field->next;
                        }
                } else {
                        while (field != NULL) {
                                struct reg_data_type *data_type = field->type;
                                if (data_type->type == REG_TYPE_ARCH_DEFINED) {
                                        if (lookup_add_arch_defined_types(arch_defined_types_list, data_type->id,
                                                                        num_arch_defined_types))
                                                gdb_generate_reg_type_description(target, tdesc, pos, size, data_type,
                                                                                arch_defined_types_list,
                                                                                num_arch_defined_types);
                                }
                        }

                        /* <struct id="id">
                         *  <field name="name" type="type"/> ...
                         * </struct> */
                        xml_printf(&retval, tdesc, pos, size,
                                        "<struct id=\"%s\">\n",
                                        type->id);
                        while (field != NULL) {
                                xml_printf(&retval, tdesc, pos, size,
                                                "<field name=\"%s\" type=\"%s\"/>\n",
                                                field->name, field->type->id);

                                field = field->next;
                        }
                }

                xml_printf(&retval, tdesc, pos, size,
                                "</struct>\n");

        } else if (type->type_class == REG_TYPE_CLASS_FLAGS) {
                /* <flags id="id" size="size">
                 *  <field name="name" start="start" end="end"/> ...
                 * </flags> */
                xml_printf(&retval, tdesc, pos, size,
                                "<flags id=\"%s\" size=\"%d\">\n",
                                type->id, type->reg_type_flags->size);

                struct reg_data_type_flags_field *field;
                field = type->reg_type_flags->fields;
                while (field != NULL) {
                        xml_printf(&retval, tdesc, pos, size,
                                        "<field name=\"%s\" start=\"%d\" end=\"%d\" type=\"%s\" />\n",
                                        field->name, field->bitfield->start, field->bitfield->end,
                                        gdb_get_reg_type_name(field->bitfield->type));

                        field = field->next;
                }

                xml_printf(&retval, tdesc, pos, size,
                                "</flags>\n");

        }

        return ERROR_OK;
}

/* Get a list of available target registers features. feature_list must
 * be freed by caller.
 */
static int get_reg_features_list(struct target *target, char const **feature_list[], int *feature_list_size,
                struct reg **reg_list, int reg_list_size)
{
        int tbl_sz = 0;

        /* Start with only one element */
        *feature_list = calloc(1, sizeof(char *));

        for (int i = 0; i < reg_list_size; i++) {
                if (reg_list[i]->exist == false)
                        continue;

                if (reg_list[i]->feature != NULL
                        && reg_list[i]->feature->name != NULL
                        && (strcmp(reg_list[i]->feature->name, ""))) {
                        /* We found a feature, check if the feature is already in the
                         * table. If not, allocate a new entry for the table and
                         * put the new feature in it.
                         */
                        for (int j = 0; j < (tbl_sz + 1); j++) {
                                if (!((*feature_list)[j])) {
                                        (*feature_list)[tbl_sz++] = reg_list[i]->feature->name;
                                        *feature_list = realloc(*feature_list, sizeof(char *) * (tbl_sz + 1));
                                        (*feature_list)[tbl_sz] = NULL;
                                        break;
                                } else {
                                        if (!strcmp((*feature_list)[j], reg_list[i]->feature->name))
                                                break;
                                }
                        }
                }
        }

        if (feature_list_size)
                *feature_list_size = tbl_sz;

        return ERROR_OK;
}

static int gdb_generate_target_description(struct target *target, char **tdesc_out)
{
        int retval = ERROR_OK;
        struct reg **reg_list = NULL;
        int reg_list_size;
        char const **features = NULL;
        char const **arch_defined_types = NULL;
        int feature_list_size = 0;
        int num_arch_defined_types = 0;
        char *tdesc = NULL;
        int pos = 0;
        int size = 0;

        arch_defined_types = calloc(1, sizeof(char *));

        retval = target_get_gdb_reg_list(target, &reg_list,
                        &reg_list_size, REG_CLASS_ALL);

        if (retval != ERROR_OK) {
                LOG_ERROR("get register list failed");
                retval = ERROR_FAIL;
                goto error;
        }

        if (reg_list_size <= 0) {
                LOG_ERROR("get register list failed");
                retval = ERROR_FAIL;
                goto error;
        }

        /* Get a list of available target registers features */
        retval = get_reg_features_list(target, &features, &feature_list_size, reg_list, reg_list_size);
        if (retval != ERROR_OK) {
                LOG_ERROR("Can't get the registers feature list");
                retval = ERROR_FAIL;
                goto error;
        }

        /* If we found some features associated with registers, create sections */
        int current_feature = 0;

        xml_printf(&retval, &tdesc, &pos, &size,
                        "<?xml version=\"1.0\"?>\n"
                        "<!DOCTYPE target SYSTEM \"gdb-target.dtd\">\n"
                        "<target version=\"1.0\">\n");

        /* generate target description according to register list */
        if (features != NULL) {
                while (features[current_feature]) {

                        xml_printf(&retval, &tdesc, &pos, &size,
                                        "<feature name=\"%s\">\n",
                                        features[current_feature]);

                        int i;
                        for (i = 0; i < reg_list_size; i++) {

                                if (reg_list[i]->exist == false)
                                        continue;

                                if (strcmp(reg_list[i]->feature->name, features[current_feature]))
                                        continue;

                                const char *type_str;
                                if (reg_list[i]->reg_data_type != NULL) {
                                        if (reg_list[i]->reg_data_type->type == REG_TYPE_ARCH_DEFINED) {
                                                /* generate <type... first, if there are architecture-defined types. */
                                                if (lookup_add_arch_defined_types(&arch_defined_types,
                                                                                reg_list[i]->reg_data_type->id,
                                                                                &num_arch_defined_types))
                                                        gdb_generate_reg_type_description(target, &tdesc, &pos, &size,
                                                                                        reg_list[i]->reg_data_type,
                                                                                        &arch_defined_types,
                                                                                        &num_arch_defined_types);

                                                type_str = reg_list[i]->reg_data_type->id;
                                        } else {
                                                /* predefined type */
                                                type_str = gdb_get_reg_type_name(
                                                                reg_list[i]->reg_data_type->type);
                                        }
                                } else {
                                        /* Default type is "int" */
                                        type_str = "int";
                                }

                                xml_printf(&retval, &tdesc, &pos, &size,
                                                "<reg name=\"%s\"", reg_list[i]->name);
                                xml_printf(&retval, &tdesc, &pos, &size,
                                                " bitsize=\"%d\"", reg_list[i]->size);
                                xml_printf(&retval, &tdesc, &pos, &size,
                                                " regnum=\"%d\"", reg_list[i]->number);
                                if (reg_list[i]->caller_save)
                                        xml_printf(&retval, &tdesc, &pos, &size,
                                                        " save-restore=\"yes\"");
                                else
                                        xml_printf(&retval, &tdesc, &pos, &size,
                                                        " save-restore=\"no\"");

                                xml_printf(&retval, &tdesc, &pos, &size,
                                                " type=\"%s\"", type_str);

                                if (reg_list[i]->group != NULL)
                                        xml_printf(&retval, &tdesc, &pos, &size,
                                                        " group=\"%s\"", reg_list[i]->group);

                                xml_printf(&retval, &tdesc, &pos, &size,
                                                "/>\n");
                        }

                        xml_printf(&retval, &tdesc, &pos, &size,
                                        "</feature>\n");

                        current_feature++;
                }
        }

        xml_printf(&retval, &tdesc, &pos, &size,
                        "</target>\n");

error:
        free(features);
        free(reg_list);
        free(arch_defined_types);

        if (retval == ERROR_OK)
                *tdesc_out = tdesc;
        else
                free(tdesc);

        return retval;
}

static int gdb_get_target_description_chunk(struct target *target, struct target_desc_format *target_desc,
                char **chunk, int32_t offset, uint32_t length)
{
        if (target_desc == NULL) {
                LOG_ERROR("Unable to Generate Target Description");
                return ERROR_FAIL;
        }

        char *tdesc = target_desc->tdesc;
        uint32_t tdesc_length = target_desc->tdesc_length;

        if (tdesc == NULL) {
                int retval = gdb_generate_target_description(target, &tdesc);
                if (retval != ERROR_OK) {
                        LOG_ERROR("Unable to Generate Target Description");
                        return ERROR_FAIL;
                }

                tdesc_length = strlen(tdesc);
        }

        char transfer_type;

        if (length < (tdesc_length - offset))
                transfer_type = 'm';
        else
                transfer_type = 'l';

        *chunk = malloc(length + 2);
        if (*chunk == NULL) {
                LOG_ERROR("Unable to allocate memory");
                return ERROR_FAIL;
        }

        (*chunk)[0] = transfer_type;
        if (transfer_type == 'm') {
                strncpy((*chunk) + 1, tdesc + offset, length);
                (*chunk)[1 + length] = '\0';
        } else {
                strncpy((*chunk) + 1, tdesc + offset, tdesc_length - offset);
                (*chunk)[1 + (tdesc_length - offset)] = '\0';

                /* After gdb-server sends out last chunk, invalidate tdesc. */
                free(tdesc);
                tdesc = NULL;
                tdesc_length = 0;
        }

        target_desc->tdesc = tdesc;
        target_desc->tdesc_length = tdesc_length;

        return ERROR_OK;
}

static int gdb_target_description_supported(struct target *target, int *supported)
{
        int retval = ERROR_OK;
        struct reg **reg_list = NULL;
        int reg_list_size = 0;
        char const **features = NULL;
        int feature_list_size = 0;

        retval = target_get_gdb_reg_list(target, &reg_list,
                        &reg_list_size, REG_CLASS_ALL);
        if (retval != ERROR_OK) {
                LOG_ERROR("get register list failed");
                goto error;
        }

        if (reg_list_size <= 0) {
                LOG_ERROR("get register list failed");
                retval = ERROR_FAIL;
                goto error;
        }

        /* Get a list of available target registers features */
        retval = get_reg_features_list(target, &features, &feature_list_size, reg_list, reg_list_size);
        if (retval != ERROR_OK) {
                LOG_ERROR("Can't get the registers feature list");
                goto error;
        }

        if (supported) {
                if (feature_list_size)
                        *supported = 1;
                else
                        *supported = 0;
        }

error:
        free(features);

        free(reg_list);

        return retval;
}

static int gdb_generate_thread_list(struct target *target, char **thread_list_out)
{
        struct rtos *rtos = target->rtos;
        int retval = ERROR_OK;
        char *thread_list = NULL;
        int pos = 0;
        int size = 0;

        xml_printf(&retval, &thread_list, &pos, &size,
                   "<?xml version=\"1.0\"?>\n"
                   "<threads>\n");

        if (rtos != NULL) {
                for (int i = 0; i < rtos->thread_count; i++) {
                        struct thread_detail *thread_detail = &rtos->thread_details[i];

                        if (!thread_detail->exists)
                                continue;

                        xml_printf(&retval, &thread_list, &pos, &size,
                                   "<thread id=\"%" PRIx64 "\">", thread_detail->threadid);

                        if (thread_detail->thread_name_str != NULL)
                                xml_printf(&retval, &thread_list, &pos, &size,
                                           "Name: %s", thread_detail->thread_name_str);

                        if (thread_detail->extra_info_str != NULL) {
                                if (thread_detail->thread_name_str != NULL)
                                        xml_printf(&retval, &thread_list, &pos, &size,
                                                   ", ");
                                xml_printf(&retval, &thread_list, &pos, &size,
                                           thread_detail->extra_info_str);
                        }

                        xml_printf(&retval, &thread_list, &pos, &size,
                                   "</thread>\n");
                }
        }

        xml_printf(&retval, &thread_list, &pos, &size,
                   "</threads>\n");

        if (retval == ERROR_OK)
                *thread_list_out = thread_list;
        else
                free(thread_list);

        return retval;
}

static int gdb_get_thread_list_chunk(struct target *target, char **thread_list,
                char **chunk, int32_t offset, uint32_t length)
{
        if (*thread_list == NULL) {
                int retval = gdb_generate_thread_list(target, thread_list);
                if (retval != ERROR_OK) {
                        LOG_ERROR("Unable to Generate Thread List");
                        return ERROR_FAIL;
                }
        }

        size_t thread_list_length = strlen(*thread_list);
        char transfer_type;

        length = MIN(length, thread_list_length - offset);
        if (length < (thread_list_length - offset))
                transfer_type = 'm';
        else
                transfer_type = 'l';

        *chunk = malloc(length + 2 + 3);
    /* Allocating extra 3 bytes prevents false positive valgrind report
         * of strlen(chunk) word access:
         * Invalid read of size 4
         * Address 0x4479934 is 44 bytes inside a block of size 45 alloc'd */
        if (*chunk == NULL) {
                LOG_ERROR("Unable to allocate memory");
                return ERROR_FAIL;
        }

        (*chunk)[0] = transfer_type;
        strncpy((*chunk) + 1, (*thread_list) + offset, length);
        (*chunk)[1 + length] = '\0';

        /* After gdb-server sends out last chunk, invalidate thread list. */
        if (transfer_type == 'l') {
                free(*thread_list);
                *thread_list = NULL;
        }

        return ERROR_OK;
}

static int gdb_query_packet(struct connection *connection,
                char const *packet, int packet_size)
{
        struct command_context *cmd_ctx = connection->cmd_ctx;
        struct gdb_connection *gdb_connection = connection->priv;
        struct target *target = get_target_from_connection(connection);

        if (strncmp(packet, "qRcmd,", 6) == 0) {
                if (packet_size > 6) {
                        char *cmd;
                        cmd = malloc((packet_size - 6) / 2 + 1);
                        size_t len = unhexify((uint8_t *)cmd, packet + 6, (packet_size - 6) / 2);
                        cmd[len] = 0;

                        /* We want to print all debug output to GDB connection */
                        log_add_callback(gdb_log_callback, connection);
                        target_call_timer_callbacks_now();
                        /* some commands need to know the GDB connection, make note of current
                         * GDB connection. */
                        current_gdb_connection = gdb_connection;
                        command_run_line(cmd_ctx, cmd);
                        current_gdb_connection = NULL;
                        target_call_timer_callbacks_now();
                        log_remove_callback(gdb_log_callback, connection);
                        free(cmd);
                }
                gdb_put_packet(connection, "OK", 2);
                return ERROR_OK;
        } else if (strncmp(packet, "qCRC:", 5) == 0) {
                if (packet_size > 5) {
                        int retval;
                        char gdb_reply[10];
                        char *separator;
                        uint32_t checksum;
                        target_addr_t addr = 0;
                        uint32_t len = 0;

                        /* skip command character */
                        packet += 5;

                        addr = strtoull(packet, &separator, 16);

                        if (*separator != ',') {
                                LOG_ERROR("incomplete read memory packet received, dropping connection");
                                return ERROR_SERVER_REMOTE_CLOSED;
                        }

                        len = strtoul(separator + 1, NULL, 16);

                        retval = target_checksum_memory(target, addr, len, &checksum);

                        if (retval == ERROR_OK) {
                                snprintf(gdb_reply, 10, "C%8.8" PRIx32 "", checksum);
                                gdb_put_packet(connection, gdb_reply, 9);
                        } else {
                                retval = gdb_error(connection, retval);
                                if (retval != ERROR_OK)
                                        return retval;
                        }

                        return ERROR_OK;
                }
        } else if (strncmp(packet, "qSupported", 10) == 0) {
                /* we currently support packet size and qXfer:memory-map:read (if enabled)
                 * qXfer:features:read is supported for some targets */
                int retval = ERROR_OK;
                char *buffer = NULL;
                int pos = 0;
                int size = 0;
                int gdb_target_desc_supported = 0;

                /* we need to test that the target supports target descriptions */
                retval = gdb_target_description_supported(target, &gdb_target_desc_supported);
                if (retval != ERROR_OK) {
                        LOG_INFO("Failed detecting Target Description Support, disabling");
                        gdb_target_desc_supported = 0;
                }

                /* support may be disabled globally */
                if (gdb_use_target_description == 0) {
                        if (gdb_target_desc_supported)
                                LOG_WARNING("Target Descriptions Supported, but disabled");
                        gdb_target_desc_supported = 0;
                }

                xml_printf(&retval,
                        &buffer,
                        &pos,
                        &size,
                        "PacketSize=%x;qXfer:memory-map:read%c;qXfer:features:read%c;qXfer:threads:read+;QStartNoAckMode+;vContSupported+",
                        (GDB_BUFFER_SIZE - 1),
                        ((gdb_use_memory_map == 1) && (flash_get_bank_count() > 0)) ? '+' : '-',
                        (gdb_target_desc_supported == 1) ? '+' : '-');

                if (retval != ERROR_OK) {
                        gdb_send_error(connection, 01);
                        return ERROR_OK;
                }

                gdb_put_packet(connection, buffer, strlen(buffer));
                free(buffer);

                return ERROR_OK;
        } else if ((strncmp(packet, "qXfer:memory-map:read::", 23) == 0)
                   && (flash_get_bank_count() > 0))
                return gdb_memory_map(connection, packet, packet_size);
        else if (strncmp(packet, "qXfer:features:read:", 20) == 0) {
                char *xml = NULL;
                int retval = ERROR_OK;

                int offset;
                unsigned int length;

                /* skip command character */
                packet += 20;

                if (decode_xfer_read(packet, NULL, &offset, &length) < 0) {
                        gdb_send_error(connection, 01);
                        return ERROR_OK;
                }

                /* Target should prepare correct target description for annex.
                 * The first character of returned xml is 'm' or 'l'. 'm' for
                 * there are *more* chunks to transfer. 'l' for it is the *last*
                 * chunk of target description.
                 */
                retval = gdb_get_target_description_chunk(target, &gdb_connection->target_desc,
                                &xml, offset, length);
                if (retval != ERROR_OK) {
                        gdb_error(connection, retval);
                        return retval;
                }

                gdb_put_packet(connection, xml, strlen(xml));

                free(xml);
                return ERROR_OK;
        } else if (strncmp(packet, "qXfer:threads:read:", 19) == 0) {
                char *xml = NULL;
                int retval = ERROR_OK;

                int offset;
                unsigned int length;

                /* skip command character */
                packet += 19;

                if (decode_xfer_read(packet, NULL, &offset, &length) < 0) {
                        gdb_send_error(connection, 01);
                        return ERROR_OK;
                }

                /* Target should prepare correct thread list for annex.
                 * The first character of returned xml is 'm' or 'l'. 'm' for
                 * there are *more* chunks to transfer. 'l' for it is the *last*
                 * chunk of target description.
                 */
                retval = gdb_get_thread_list_chunk(target, &gdb_connection->thread_list,
                                                   &xml, offset, length);
                if (retval != ERROR_OK) {
                        gdb_error(connection, retval);
                        return retval;
                }

                gdb_put_packet(connection, xml, strlen(xml));

                free(xml);
                return ERROR_OK;
        } else if (strncmp(packet, "QStartNoAckMode", 15) == 0) {
                gdb_connection->noack_mode = 1;
                gdb_put_packet(connection, "OK", 2);
                return ERROR_OK;
        }

        gdb_put_packet(connection, "", 0);
        return ERROR_OK;
}

static bool gdb_handle_vcont_packet(struct connection *connection, const char *packet, int packet_size)
{
        struct gdb_connection *gdb_connection = connection->priv;
        struct target *target = get_target_from_connection(connection);
        const char *parse = packet;
        int retval;

        /* query for vCont supported */
        if (parse[0] == '?') {
                if (target->type->step != NULL) {
                        /* gdb doesn't accept c without C and s without S */
                        gdb_put_packet(connection, "vCont;c;C;s;S", 13);
                        return true;
                }
                return false;
        }

        if (parse[0] == ';') {
                ++parse;
                --packet_size;
        }

        /* simple case, a continue packet */
        if (parse[0] == 'c') {
                LOG_DEBUG("target %s continue", target_name(target));
                log_add_callback(gdb_log_callback, connection);
                retval = target_resume(target, 1, 0, 0, 0);
                if (retval == ERROR_TARGET_NOT_HALTED)
                        LOG_INFO("target %s was not halted when resume was requested", target_name(target));

                /* poll target in an attempt to make its internal state consistent */
                if (retval != ERROR_OK) {
                        retval = target_poll(target);
                        if (retval != ERROR_OK)
                                LOG_DEBUG("error polling target %s after failed resume", target_name(target));
                }

                /*
                 * We don't report errors to gdb here, move frontend_state to
                 * TARGET_RUNNING to stay in sync with gdb's expectation of the
                 * target state
                 */
                gdb_connection->frontend_state = TARGET_RUNNING;
                target_call_event_callbacks(target, TARGET_EVENT_GDB_START);

                return true;
        }

        /* single-step or step-over-breakpoint */
        if (parse[0] == 's') {
                bool fake_step = false;

                if (strncmp(parse, "s:", 2) == 0) {
                        struct target *ct = target;
                        int current_pc = 1;
                        int64_t thread_id;
                        char *endp;

                        parse += 2;
                        packet_size -= 2;

                        thread_id = strtoll(parse, &endp, 16);
                        if (endp != NULL) {
                                packet_size -= endp - parse;
                                parse = endp;
                        }

                        if (target->rtos != NULL) {
                                /* FIXME: why is this necessary? rtos state should be up-to-date here already! */
                                rtos_update_threads(target);

                                target->rtos->gdb_target_for_threadid(connection, thread_id, &ct);

                                /*
                                 * check if the thread to be stepped is the current rtos thread
                                 * if not, we must fake the step
                                 */
                                if (target->rtos->current_thread != thread_id)
                                        fake_step = true;
                        }

                        if (parse[0] == ';') {
                                ++parse;
                                --packet_size;

                                if (parse[0] == 'c') {
                                        parse += 1;
                                        packet_size -= 1;

                                        /* check if thread-id follows */
                                        if (parse[0] == ':') {
                                                int64_t tid;
                                                parse += 1;
                                                packet_size -= 1;

                                                tid = strtoll(parse, &endp, 16);
                                                if (tid == thread_id) {
                                                        /*
                                                         * Special case: only step a single thread (core),
                                                         * keep the other threads halted. Currently, only
                                                         * aarch64 target understands it. Other target types don't
                                                         * care (nobody checks the actual value of 'current')
                                                         * and it doesn't really matter. This deserves
                                                         * a symbolic constant and a formal interface documentation
                                                         * at a later time.
                                                         */
                                                        LOG_DEBUG("request to step current core only");
                                                        /* uncomment after checking that indeed other targets are safe */
                                                        /*current_pc = 2;*/
                                                }
                                        }
                                }
                        }

                        LOG_DEBUG("target %s single-step thread %"PRIx64, target_name(ct), thread_id);
                        log_add_callback(gdb_log_callback, connection);
                        target_call_event_callbacks(ct, TARGET_EVENT_GDB_START);

                        /*
                         * work around an annoying gdb behaviour: when the current thread
                         * is changed in gdb, it assumes that the target can follow and also
                         * make the thread current. This is an assumption that cannot hold
                         * for a real target running a multi-threading OS. We just fake
                         * the step to not trigger an internal error in gdb. See
                         * https://sourceware.org/bugzilla/show_bug.cgi?id=22925 for details
                         */
                        if (fake_step) {
                                int sig_reply_len;
                                char sig_reply[128];

                                LOG_DEBUG("fake step thread %"PRIx64, thread_id);

                                sig_reply_len = snprintf(sig_reply, sizeof(sig_reply),
                                                                                 "T05thread:%016"PRIx64";", thread_id);

                                gdb_put_packet(connection, sig_reply, sig_reply_len);
                                log_remove_callback(gdb_log_callback, connection);

                                return true;
                        }

                        /* support for gdb_sync command */
                        if (gdb_connection->sync) {
                                gdb_connection->sync = false;
                                if (ct->state == TARGET_HALTED) {
                                        LOG_WARNING("stepi ignored. GDB will now fetch the register state " \
                                                                        "from the target.");
                                        gdb_sig_halted(connection);
                                        log_remove_callback(gdb_log_callback, connection);
                                } else
                                        gdb_connection->frontend_state = TARGET_RUNNING;
                                return true;
                        }

                        retval = target_step(ct, current_pc, 0, 0);
                        if (retval == ERROR_TARGET_NOT_HALTED)
                                LOG_INFO("target %s was not halted when step was requested", target_name(ct));

                        /* if step was successful send a reply back to gdb */
                        if (retval == ERROR_OK) {
                                retval = target_poll(ct);
                                if (retval != ERROR_OK)
                                        LOG_DEBUG("error polling target %s after successful step", target_name(ct));
                                /* send back signal information */
                                gdb_signal_reply(ct, connection);
                                /* stop forwarding log packets! */
                                log_remove_callback(gdb_log_callback, connection);
                        } else
                                gdb_connection->frontend_state = TARGET_RUNNING;
                } else {
                        LOG_ERROR("Unknown vCont packet");
                        return false;
                }
                return true;
        }

        return false;
}

static int gdb_v_packet(struct connection *connection,
                char const *packet, int packet_size)
{
        struct gdb_connection *gdb_connection = connection->priv;
        struct target *target;
        int result;

        target = get_target_from_connection(connection);

        if (strncmp(packet, "vCont", 5) == 0) {
                bool handled;

                packet += 5;
                packet_size -= 5;

                handled = gdb_handle_vcont_packet(connection, packet, packet_size);
                if (!handled)
                        gdb_put_packet(connection, "", 0);

                return ERROR_OK;
        }

        /* if flash programming disabled - send a empty reply */

        if (gdb_flash_program == 0) {
                gdb_put_packet(connection, "", 0);
                return ERROR_OK;
        }

        if (strncmp(packet, "vFlashErase:", 12) == 0) {
                unsigned long addr;
                unsigned long length;

                char const *parse = packet + 12;
                if (*parse == '\0') {
                        LOG_ERROR("incomplete vFlashErase packet received, dropping connection");
                        return ERROR_SERVER_REMOTE_CLOSED;
                }

                addr = strtoul(parse, (char **)&parse, 16);

                if (*(parse++) != ',' || *parse == '\0') {
                        LOG_ERROR("incomplete vFlashErase packet received, dropping connection");
                        return ERROR_SERVER_REMOTE_CLOSED;
                }

                length = strtoul(parse, (char **)&parse, 16);

                if (*parse != '\0') {
                        LOG_ERROR("incomplete vFlashErase packet received, dropping connection");
                        return ERROR_SERVER_REMOTE_CLOSED;
                }

                /* assume all sectors need erasing - stops any problems
                 * when flash_write is called multiple times */
                flash_set_dirty();

                /* perform any target specific operations before the erase */
                target_call_event_callbacks(target,
                        TARGET_EVENT_GDB_FLASH_ERASE_START);

                /* vFlashErase:addr,length messages require region start and
                 * end to be "block" aligned ... if padding is ever needed,
                 * GDB will have become dangerously confused.
                 */
                result = flash_erase_address_range(target, false, addr,
                        length);

                /* perform any target specific operations after the erase */
                target_call_event_callbacks(target,
                        TARGET_EVENT_GDB_FLASH_ERASE_END);

                /* perform erase */
                if (result != ERROR_OK) {
                        /* GDB doesn't evaluate the actual error number returned,
                         * treat a failed erase as an I/O error
                         */
                        gdb_send_error(connection, EIO);
                        LOG_ERROR("flash_erase returned %i", result);
                } else
                        gdb_put_packet(connection, "OK", 2);

                return ERROR_OK;
        }

        if (strncmp(packet, "vFlashWrite:", 12) == 0) {
                int retval;
                unsigned long addr;
                unsigned long length;
                char const *parse = packet + 12;

                if (*parse == '\0') {
                        LOG_ERROR("incomplete vFlashErase packet received, dropping connection");
                        return ERROR_SERVER_REMOTE_CLOSED;
                }
                addr = strtoul(parse, (char **)&parse, 16);
                if (*(parse++) != ':') {
                        LOG_ERROR("incomplete vFlashErase packet received, dropping connection");
                        return ERROR_SERVER_REMOTE_CLOSED;
                }
                length = packet_size - (parse - packet);

                /* create a new image if there isn't already one */
                if (gdb_connection->vflash_image == NULL) {
                        gdb_connection->vflash_image = malloc(sizeof(struct image));
                        image_open(gdb_connection->vflash_image, "", "build");
                }

                /* create new section with content from packet buffer */
                retval = image_add_section(gdb_connection->vflash_image,
                                addr, length, 0x0, (uint8_t const *)parse);
                if (retval != ERROR_OK)
                        return retval;

                gdb_put_packet(connection, "OK", 2);

                return ERROR_OK;
        }

        if (strncmp(packet, "vFlashDone", 10) == 0) {
                uint32_t written;

                /* process the flashing buffer. No need to erase as GDB
                 * always issues a vFlashErase first. */
                target_call_event_callbacks(target,
                                TARGET_EVENT_GDB_FLASH_WRITE_START);
                result = flash_write(target, gdb_connection->vflash_image,
                        &written, 0);
                target_call_event_callbacks(target,
                        TARGET_EVENT_GDB_FLASH_WRITE_END);
                if (result != ERROR_OK) {
                        if (result == ERROR_FLASH_DST_OUT_OF_BANK)
                                gdb_put_packet(connection, "E.memtype", 9);
                        else
                                gdb_send_error(connection, EIO);
                } else {
                        LOG_DEBUG("wrote %u bytes from vFlash image to flash", (unsigned)written);
                        gdb_put_packet(connection, "OK", 2);
                }

                image_close(gdb_connection->vflash_image);
                free(gdb_connection->vflash_image);
                gdb_connection->vflash_image = NULL;

                return ERROR_OK;
        }

        gdb_put_packet(connection, "", 0);
        return ERROR_OK;
}

static int gdb_detach(struct connection *connection)
{
        target_call_event_callbacks(get_target_from_connection(connection),
                TARGET_EVENT_GDB_DETACH);

        return gdb_put_packet(connection, "OK", 2);
}

/* The format of 'F' response packet is
 * Fretcode,errno,Ctrl-C flag;call-specific attachment
 */
static int gdb_fileio_response_packet(struct connection *connection,
                char const *packet, int packet_size)
{
        struct target *target = get_target_from_connection(connection);
        char *separator;
        char *parsing_point;
        int fileio_retcode = strtoul(packet + 1, &separator, 16);
        int fileio_errno = 0;
        bool fileio_ctrl_c = false;
        int retval;

        LOG_DEBUG("-");

        if (*separator == ',') {
                parsing_point = separator + 1;
                fileio_errno = strtoul(parsing_point, &separator, 16);
                if (*separator == ',') {
                        if (*(separator + 1) == 'C') {
                                /* TODO: process ctrl-c */
                                fileio_ctrl_c = true;
                        }
                }
        }

        LOG_DEBUG("File-I/O response, retcode: 0x%x, errno: 0x%x, ctrl-c: %s",
                        fileio_retcode, fileio_errno, fileio_ctrl_c ? "true" : "false");

        retval = target_gdb_fileio_end(target, fileio_retcode, fileio_errno, fileio_ctrl_c);
        if (retval != ERROR_OK)
                return ERROR_FAIL;

        /* After File-I/O ends, keep continue or step */
        if (gdb_running_type == 'c')
                retval = target_resume(target, 1, 0x0, 0, 0);
        else if (gdb_running_type == 's')
                retval = target_step(target, 1, 0x0, 0);
        else
                retval = ERROR_FAIL;

        if (retval != ERROR_OK)
                return ERROR_FAIL;

        return ERROR_OK;
}