gdb/gdb-cli-add-ignore-errors-command.patch

[gdb/cli] Add ignore-errors command

While trying to reproduce a failing test-case from the testsuite on the
command line using a gdb command script, I ran into the problem that a command
failed which stopped script execution.

I could work around this by splitting the script at each error, but I realized
it would be nice if I could tell gdb to ignore the error.

A python workaround ignore-errors exists, mentioned here (
https://sourceware.org/legacy-ml/gdb/2010-06/msg00100.html ), which is
already supplied by distros like Fedora and openSUSE.

FTR, a more elaborate try-catch solution was posted here (
https://sourceware.org/bugzilla/show_bug.cgi?id=8487 ).

This patch adds native ignore-errors support (so no python needed).

So with this script:
...
$ cat script.gdb
ignore-errors run
echo here
...
we have:
...
$ gdb -q -batch -x script.gdb
No executable file specified.
Use the "file" or "exec-file" command.
here$
...

Note that quit is not caught:
...
$ gdb -q
(gdb) ignore-errors quit
$
...
which is the same behaviour as with the python implementation.

Tested on x86_64-linux.

gdb/ChangeLog:

2021-05-18  Tom de Vries  <tdevries@suse.de>

	* cli/cli-cmds.c (ignore_errors_command_completer)
	(ignore_errors_command): New function.
	(_initialize_cli_cmds): Add "ignore-errors" cmd.

gdb/doc/ChangeLog:

2021-05-18  Tom de Vries  <tdevries@suse.de>

	* gdb.texinfo (Command Files): Document command ignore-errors.

gdb/testsuite/ChangeLog:

2021-05-18  Tom de Vries  <tdevries@suse.de>

	* gdb.base/ignore-errors.exp: New test.
	* gdb.base/ignore-errors.gdb: New command file.

---
 gdb/cli/cli-cmds.c                       | 35 ++++++++++++++++++++++++++++++++
 gdb/doc/gdb.texinfo                      |  8 +++++++-
 gdb/testsuite/gdb.base/ignore-errors.exp | 24 ++++++++++++++++++++++
 gdb/testsuite/gdb.base/ignore-errors.gdb |  2 ++
 4 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/gdb/cli/cli-cmds.c b/gdb/cli/cli-cmds.c
index 56ae12a0c19..ce8af45a925 100644
--- a/gdb/cli/cli-cmds.c
+++ b/gdb/cli/cli-cmds.c
@@ -39,6 +39,7 @@
 #include "gdbsupport/filestuff.h"
 #include "location.h"
 #include "block.h"
+#include "event-top.h"
 
 #include "ui-out.h"
 #include "interps.h"
@@ -2249,6 +2250,34 @@ gdb_maint_setting_str_internal_fn (struct gdbarch *gdbarch,
 				 gdbarch);
 }
 
+/* Completer for "ignore-errors".  */
+
+static void
+ignore_errors_command_completer (cmd_list_element *ignore,
+				 completion_tracker &tracker,
+				 const char *text, const char * /*word*/)
+{
+  complete_nested_command_line (tracker, text);
+}
+
+/* Implementation of the ignore-errors command.  */
+
+static void
+ignore_errors_command (const char *args, int from_tty)
+{
+  try
+    {
+      execute_command (args, from_tty);
+    }
+  catch (const gdb_exception_error &ex)
+    {
+      exception_print (gdb_stderr, ex);
+
+      /* See also execute_gdb_command.  */
+      async_enable_stdin ();
+    }
+}
+
 void _initialize_cli_cmds ();
 void
 _initialize_cli_cmds ()
@@ -2625,4 +2654,10 @@ when GDB is started."), GDBINIT);
   c = add_cmd ("source", class_support, source_command,
 	       source_help_text, &cmdlist);
   set_cmd_completer (c, filename_completer);
+
+  c = add_cmd ("ignore-errors", class_support, ignore_errors_command,
+	       _("Execute a single command, ignoring all errors.\n"
+		 "Only one-line commands are supported.\n"
+		 "This is primarily useful in scripts."), &cmdlist);
+  set_cmd_completer (c, ignore_errors_command_completer);
 }
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 025d6bec42a..1700b0305c5 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -27508,7 +27508,8 @@ The lines in a command file are generally executed sequentially,
 unless the order of execution is changed by one of the
 @emph{flow-control commands} described below.  The commands are not
 printed as they are executed.  An error in any command terminates
-execution of the command file and control is returned to the console.
+execution of the command file and control is returned to the console,
+unless the line is prefixed with the @code{ignore-errors} command.
 
 @value{GDBN} first searches for @var{filename} in the current directory.
 If the file is not found there, and @var{filename} does not specify a
@@ -27603,6 +27604,11 @@ the controlling expression.
 @item end
 Terminate the block of commands that are the body of @code{if},
 @code{else}, or @code{while} flow-control commands.
+
+@kindex ignore-errors
+@item ignore-errors
+This command executes the command specified by its arguments, but
+doesn't stop execution of the script if the command fails.
 @end table
 
 
diff --git a/gdb/testsuite/gdb.base/ignore-errors.exp b/gdb/testsuite/gdb.base/ignore-errors.exp
new file mode 100644
index 00000000000..30dac7a94e2
--- /dev/null
+++ b/gdb/testsuite/gdb.base/ignore-errors.exp
@@ -0,0 +1,24 @@
+# Copyright 2021 Free Software Foundation, Inc.
+
+# 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 3 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/>.  */
+
+# Check command ignore-errors.
+
+clean_restart
+
+gdb_test "source ignore-errors.gdb" \
+    [multi_line \
+	 "No executable file specified\\." \
+	 "Use the \"file\" or \"exec-file\" command\\." \
+	 "here"]
diff --git a/gdb/testsuite/gdb.base/ignore-errors.gdb b/gdb/testsuite/gdb.base/ignore-errors.gdb
new file mode 100644
index 00000000000..5962ff49b11
--- /dev/null
+++ b/gdb/testsuite/gdb.base/ignore-errors.gdb
@@ -0,0 +1,2 @@
+ignore-errors run
+echo here\n