Re: Test for regex module hangs

[Eric Blake]

On 01/31/2013 03:54 PM, Eric Blake wrote:
> On 01/31/2013 03:13 PM, Reuben Thomas wrote:
>> By the way, until this bug is fixed, a reasonable workaround is to pass
>> --with-included-regex to configure.
>>
>>
>> On 30 January 2013 13:50, Reuben Thomas <address@hidden> wrote:
>>
>>> When running the test for working re_compile_pattern, I get a hang;
>>> attaching to the process gives me:
>>>
>>> (gdb) where
>>> #0  __lll_lock_wait_private () at
>>> ../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:93
>>> #1  0x00002ab6dd5c6221 in _L_lock_10625 () at malloc.c:5209
> 
> I was able to reproduce the hang in an Ubuntu VM, although I could not
> reproduce it using Fedora 16 with glibc 1.14.90.  At any rate, it's easy

2.14.90

> enough to fix; I'll add an alarm() handler to the m4 test (same as we
> have done for other tests that hang).

Here it is:

From a0b25daf001cb1a0352f329e2b5e1640acc88541 Mon Sep 17 00:00:00 2001
From: Eric Blake <address@hidden>
Date: Thu, 31 Jan 2013 15:57:38 -0700
Subject: [PATCH] regex: avoid infinite configure test

At least glibc 2.15 on Ubuntu ended up hanging.

* m4/regex.m4 (gl_REGEX): Add an alarm escape hatch.
Reported by Reuben Thomas.

Signed-off-by: Eric Blake <address@hidden>
---
 ChangeLog   |  5 +++++
 m4/regex.m4 | 12 +++++++++++-
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/ChangeLog b/ChangeLog
index c18cbad..74dad7e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2013-01-31  Eric Blake  <address@hidden>
+
+       regex: avoid infinite configure test
+       * m4/regex.m4 (gl_REGEX): Add an alarm escape hatch.
+
 2013-01-31  Reuben Thomas  <address@hidden>

        openpty: fix bug where HAVE_OPENPTY wasn't defined
diff --git a/m4/regex.m4 b/m4/regex.m4
index 2f5bd09..944dfaf 100644
--- a/m4/regex.m4
+++ b/m4/regex.m4
@@ -1,4 +1,4 @@
-# serial 62
+# serial 63

 # Copyright (C) 1996-2001, 2003-2013 Free Software Foundation, Inc.
 #
@@ -27,6 +27,7 @@ AC_DEFUN([gl_REGEX],
     # following run test, then default to *not* using the included regex.c.
     # If cross compiling, assume the test would fail and use the included
     # regex.c.
+    AC_CHECK_FUNCS_ONCE([alarm])
     AC_CACHE_CHECK([for working re_compile_pattern],
                    [gl_cv_func_re_compile_pattern_working],
       [AC_RUN_IFELSE(
@@ -35,6 +36,10 @@ AC_DEFUN([gl_REGEX],
            #include <locale.h>
            #include <limits.h>
            #include <regex.h>
+           #if HAVE_ALARM
+           # include <unistd.h>
+           # include <signal.h>
+           #endif
            ]],
           [[int result = 0;
             static struct re_pattern_buffer regex;
@@ -43,6 +48,11 @@ AC_DEFUN([gl_REGEX],
             const char *s;
             struct re_registers regs;

+#if HAVE_ALARM
+            /* Some builds of glibc go into an infinite loop on this
test.  */
+            signal (SIGALRM, SIG_DFL);
+            alarm (2);
+#endif
             if (setlocale (LC_ALL, "en_US.UTF-8"))
               {
                 {
-- 
1.8.1


-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org

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