Re: [readline patch, gdb-7.3?] Avoid free from a signal handler [Re: [PATCH] Make interrupting tab-completion safe.]

Jan Kratochvil
2011-06-29T21:49:29Z

On Mon, 27 Jun 2011 18:03:07 +0200, Joel Brobecker wrote:
> > readline/
> > 2011-06-27 Jan Kratochvil <jan.kratochvil@redhat.com>
> >
> > Avoid free from a signal handler.
> > * Makefile.in (xfree.o): Add readline.h.
> > * xfree.c: Include stdio.h and readline.h.
> > (xfree): Return on RL_STATE_SIGHANDLER.
> > * xmalloc.h (xfree): New definition.
>
> Interesting. OK for gdb-7.3 if OK for readline...

Checked in the original patch for trunk:
http://sourceware.org/ml/gdb-cvs/2011-06/msg00168.html

For gdb-7.3 it is more complicated as it still has readline-5.1, checked in
there the patch below, it is not nice but I find it OK for the branch.

Thanks,
Jan

gdb_7_3-branch:
http://sourceware.org/ml/gdb-cvs/2011-06/msg00169.html

--- src/readline/ChangeLog.gdb 2011/03/04 18:12:47 1.38
+++ src/readline/ChangeLog.gdb 2011/06/29 21:46:43 1.38.2.1
@@ -1,3 +1,12 @@
+2011-06-27 Jan Kratochvil <jan.kratochvil@redhat.com>
+
+ Avoid free from a signal handler.
+ * Makefile.in (xmalloc.o): Add readline.h.
+ * xmalloc.c: Include readline.h.
+ (xmalloc, xrealloc): Disable them by #if 0.
+ (xfree): Return on RL_STATE_SIGHANDLER, #undef free.
+ * xmalloc.h (xfree, free): New definition.
+
2011-03-04 Michael Snyder <msnyder@vmware.com>

* bind.c (rl_function_dumper): Free allocated memory.
--- src/readline/Makefile.in 2009/07/30 22:53:17 1.11
+++ src/readline/Makefile.in 2011/06/29 21:46:43 1.11.8.1
@@ -417,7 +417,7 @@
vi_mode.o: readline.h keymaps.h rltypedefs.h chardefs.h tilde.h
vi_mode.o: history.h ansi_stdlib.h rlstdc.h
xmalloc.o: ${BUILD_DIR}/config.h
-xmalloc.o: ansi_stdlib.h
+xmalloc.o: ansi_stdlib.h readline.h

bind.o: rlshell.h
histfile.o: rlshell.h
--- src/readline/xmalloc.c 2006/04/20 20:13:20 1.5
+++ src/readline/xmalloc.c 2011/06/29 21:46:43 1.5.40.1
@@ -33,6 +33,7 @@
#endif /* HAVE_STDLIB_H */

#include "xmalloc.h"
+#include "readline.h"

/* **************************************************************** */
/* */
@@ -40,6 +41,9 @@
/* */
/* **************************************************************** */

+/* xmalloc and xrealloc are provided by GDB. */
+#if 0
+
static void
memory_error_and_abort (fname)
char *fname;
@@ -77,12 +81,20 @@
return (temp);
}

+/* xmalloc and xrealloc are provided by GDB. */
+#endif /* 0 */
+
/* Use this as the function to call when adding unwind protects so we
don't need to know what free() returns. */
void
xfree (string)
PTR_T string;
{
+ /* Leak a bit. */
+ if (RL_ISSTATE(RL_STATE_SIGHANDLER))
+ return;
+
+#undef free
if (string)
free (string);
}
--- src/readline/xmalloc.h 2006/04/20 20:13:20 1.4
+++ src/readline/xmalloc.h 2011/06/29 21:46:43 1.4.40.1
@@ -39,6 +39,12 @@

#endif /* !PTR_T */

+/* xmalloc and xrealloc should be also protected from RL_STATE_SIGHANDLER. */
+#define xfree xfree_readline
+
+/* readline-5.1 backport. */
+#define free xfree
+
extern PTR_T xmalloc PARAMS((size_t));
extern PTR_T xrealloc PARAMS((void *, size_t));
extern void xfree PARAMS((void *));