helper: command: drop last LF ('\n') from sequence of command_print()

The OpenOCD commands produce their TCL text result through the
pair command_print() and command_print_sameline().
The latter is used to concatenate output in a single line.

At the end of a sequence of command_print(), the last LF is taken
as part of the command result, while it is not always needed, and
it is even annoying when the output of two commands needs to be
concatenate in a single line.

Using command_print_sameline() in place of the last call to
command_print() would solve the problem but it's quite expensive
in term of coding to fix all the existing commands.

Drop the last LF, if present.
Commands that would specifically need a LF as last char, can add
an extra LF at the end of the output.
Document this behavior in command.h.

Change-Id: I6757c20fbfce923dd393083146e8d5a1f3b790b4
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/7471
Tested-by: jenkins
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>

diff --git a/src/helper/command.c b/src/helper/command.c
index ca66cf7dd1bbb2fdf37c8a8fc4e778b113840d63..12434ec90ed4eddcdcfd6ebe29c1011e8de9133c 100644 (file)
--- a/src/helper/command.c
+++ b/src/helper/command.c
@@ -543,8 +543,16 @@ static int run_command(struct command_context *context,
                if (retval != ERROR_OK)
                        LOG_DEBUG("Command '%s' failed with error code %d",
                                                words[0], retval);
-               /* Use the command output as the Tcl result */
-               Jim_SetResult(context->interp, cmd.output);
+               /*
+                * Use the command output as the Tcl result.
+                * Drop last '\n' to allow command output concatenation
+                * while keep using command_print() everywhere.
+                */
+               const char *output_txt = Jim_String(cmd.output);
+               int len = strlen(output_txt);
+               if (len && output_txt[len - 1] == '\n')
+                       --len;
+               Jim_SetResultString(context->interp, output_txt, len);
        }
        Jim_DecrRefCount(context->interp, cmd.output);
 

diff --git a/src/helper/command.h b/src/helper/command.h
index 478e5c8adaed0bc015d577a6cda819d8ab298eb8..42cb9cb7d847bb2257b34a54019a4e9451f076f8 100644 (file)
--- a/src/helper/command.h
+++ b/src/helper/command.h
@@ -370,10 +370,21 @@ struct command_context *copy_command_context(struct command_context *cmd_ctx);
  */
 void command_done(struct command_context *context);
 
+/*
+ * command_print() and command_print_sameline() are used to produce the TCL
+ * output of OpenOCD commands. command_print() automatically adds a '\n' at
+ * the end or the format string. Use command_print_sameline() to avoid the
+ * trailing '\n', e.g. to concatenate the command output in the same line.
+ * The very last '\n' of the command is stripped away (see run_command()).
+ * For commands that strictly require a '\n' as last output character, add
+ * it explicitly with either an empty command_print() or with a '\n' in the
+ * last command_print() and add a comment to document it.
+ */
 void command_print(struct command_invocation *cmd, const char *format, ...)
 __attribute__ ((format (PRINTF_ATTRIBUTE_FORMAT, 2, 3)));
 void command_print_sameline(struct command_invocation *cmd, const char *format, ...)
 __attribute__ ((format (PRINTF_ATTRIBUTE_FORMAT, 2, 3)));
+
 int command_run_line(struct command_context *context, char *line);
 int command_run_linef(struct command_context *context, const char *format, ...)
 __attribute__ ((format (PRINTF_ATTRIBUTE_FORMAT, 2, 3)));