server/gdb: fix return of gdb remote monitor command

Current implementation for gdb remote monitor command uses the
command_run_line() to execute the command.
While command_run_line() has several advantages, it unfortunately
hides the error codes and outputs the result of the command
through LOG_USER(), which is not what gdb requires. See 'qRcmd' in
https://sourceware.org/gdb/onlinedocs/gdb/General-Query-Packets.html

Replace command_run_line() with Jim_EvalObj() and parse the output
to provide the proper result to gdb.

Can be tested by defining in OpenOCD:
	proc a {} {return hello}
	proc b {} {return -code 4}
	proc c {} {return -code 4 "This is an error!"}
then by executing in gdb console:
	monitor a
	monitor b
	monitor c
	monitor foo

Change-Id: I1b85554d59221560e97861a499e16764e70c1172
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reported-by: Torbjorn Svensson <torbjorn.svensson@st.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/6886
Tested-by: jenkins

1 files changed, 42 insertions, 1 deletions

diff --git a/src/server/gdb_server.c b/src/server/gdb_server.c
index 82c8ce9..fcc87fb 100644
--- a/src/server/gdb_server.c
+++ b/src/server/gdb_server.c
@@ -2761,11 +2761,52 @@ static int gdb_query_packet(struct connection *connection,
 			/* 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);
+			struct target *saved_target_override = cmd_ctx->current_target_override;
+			cmd_ctx->current_target_override = target;
+
+			int retval = Jim_EvalObj(cmd_ctx->interp, Jim_NewStringObj(cmd_ctx->interp, cmd, -1));
+
+			cmd_ctx->current_target_override = saved_target_override;
 			current_gdb_connection = NULL;
 			target_call_timer_callbacks_now();
 			gdb_connection->output_flag = GDB_OUTPUT_NO;
 			free(cmd);
+			if (retval == JIM_RETURN)
+				retval = cmd_ctx->interp->returnCode;
+			int lenmsg;
+			const char *cretmsg = Jim_GetString(Jim_GetResult(cmd_ctx->interp), &lenmsg);
+			char *retmsg;
+			if (lenmsg && cretmsg[lenmsg - 1] != '\n') {
+				retmsg = alloc_printf("%s\n", cretmsg);
+				lenmsg++;
+			} else {
+				retmsg = strdup(cretmsg);
+			}
+			if (!retmsg)
+				return ERROR_GDB_BUFFER_TOO_SMALL;
+
+			if (retval == JIM_OK) {
+				if (lenmsg) {
+					char *hex_buffer = malloc(lenmsg * 2 + 1);
+					if (!hex_buffer) {
+						free(retmsg);
+						return ERROR_GDB_BUFFER_TOO_SMALL;
+					}
+
+					size_t pkt_len = hexify(hex_buffer, (const uint8_t *)retmsg, lenmsg,
+											lenmsg * 2 + 1);
+					gdb_put_packet(connection, hex_buffer, pkt_len);
+					free(hex_buffer);
+				} else {
+					gdb_put_packet(connection, "OK", 2);
+				}
+			} else {
+				if (lenmsg)
+					gdb_output_con(connection, retmsg);
+				gdb_send_error(connection, retval);
+			}
+			free(retmsg);
+			return ERROR_OK;
 		}
 		gdb_put_packet(connection, "OK", 2);
 		return ERROR_OK;