Re: [patch] Fix testsuite annotate-quit race (PR 544)

Daniel Jacobowitz
2008-03-21T21:04:04Z

On Fri, Mar 21, 2008 at 09:45:06PM +0100, Jan Kratochvil wrote:
> The patch was approved by the readline maintainer:

Great! Thank you for pursuing this.

> On Fri, 21 Mar 2008 19:37:31 +0100, Chet Ramey wrote:
> > I will add something like your block_sigint/release_sigint changes around
> > the guts of rl_redisplay. That's the right thing to do anyway. It will
> > probably not come out as a patch for readline-5.2; you can use your
> > current patch (though the names will change to _rl_block_sigint and
> > _rl_release_sigint -- fair warning).
>
> It could be probably also coded only in GDB by modifying the function pointer
> RL_REDISPLAY_FUNCTION instead to a custom wrapper calling RL_REDISPLAY but it
> would need the SIGINT blocking/handling done in GDB.
>
> OK to commit as a readline fork before readline-6 is here?

We have a --with-system-readline option, which many distributors use
instead of the internal readline. So I would rather fix it in GDB.
I did it just the way you suggested.

I'm running some stress tests with this patch. So far it hasn't
failed once.

--
Daniel Jacobowitz
CodeSourcery

2008-03-21 Daniel Jacobowitz <dan@codesourcery.com>

PR gdb/544
Suggested by Jan Kratochvil:
* top.c (gdb_rl_operate_and_get_next_completion): Call
rl_redisplay_function.
(gdb_rl_redisplay): New.
(init_main): Set rl_redisplay_function.

Index: top.c
===================================================================
RCS file: /cvs/src/src/gdb/top.c,v
retrieving revision 1.135
diff -u -p -r1.135 top.c
--- top.c 21 Mar 2008 14:39:22 -0000 1.135
+++ top.c 21 Mar 2008 21:01:37 -0000
@@ -921,7 +921,7 @@ gdb_rl_operate_and_get_next_completion (
operate_saved_history = -1;

/* readline doesn't automatically update the display for us. */
- rl_redisplay ();
+ rl_redisplay_function ();

after_char_processing_hook = NULL;
rl_pre_input_hook = NULL;
@@ -956,6 +956,29 @@ gdb_rl_operate_and_get_next (int count,

return rl_newline (1, key);
}
+
+/* Readline 5.2 and earlier do not block SIGINT while redrawing the prompt.
+ This can lead to corrupted internal state. As long as we do not require
+ a newer readline version, compensate for it. */
+static void
+gdb_rl_redisplay (void)
+{
+#if HAVE_SIGPROCMASK
+ sigset_t sigint_set, sigint_oset;
+
+ sigemptyset (&sigint_set);
+ sigemptyset (&sigint_oset);
+ sigaddset (&sigint_set, SIGINT);
+ sigprocmask (SIG_BLOCK, &sigint_set, &sigint_oset);
+#endif
+
+ rl_redisplay ();
+
+#if HAVE_SIGPROCMASK
+ sigprocmask (SIG_SETMASK, &sigint_oset, (sigset_t *)NULL);
+#endif
+}
+
\f
/* Read one line from the command input stream `instream'
into the local static buffer `linebuffer' (whose current length
@@ -1581,6 +1604,7 @@ init_main (void)
rl_completer_quote_characters = get_gdb_completer_quote_characters ();
rl_readline_name = "gdb";
rl_terminal_name = getenv ("TERM");
+ rl_redisplay_function = gdb_rl_redisplay;

/* The name for this defun comes from Bash, where it originated.
15 is Control-o, the same binding this function has in Bash. */