From: Eric Blake <eblake@redhat.com>
Date: Thu, 31 Jan 2013 22:57:38 +0000 (-0700)
Subject: regex: avoid infinite configure test
X-Git-Tag: v0.1~224
X-Git-Url: http://erislabs.net/gitweb/?p=gnulib.git;a=commitdiff_plain;h=a0b25daf001cb1a0352f329e2b5e1640acc88541

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 <eblake@redhat.com>
---

diff --git a/ChangeLog b/ChangeLog
index c18cbad98..74dad7e2b 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2013-01-31  Eric Blake  <eblake@redhat.com>
+
+	regex: avoid infinite configure test
+	* m4/regex.m4 (gl_REGEX): Add an alarm escape hatch.
+
 2013-01-31  Reuben Thomas  <rrt@sc3d.org>
 
 	openpty: fix bug where HAVE_OPENPTY wasn't defined
diff --git a/m4/regex.m4 b/m4/regex.m4
index 2f5bd0973..944dfaf90 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"))
               {
                 {