Mercurial > gnulib
view m4/strcasestr.m4 @ 37246:5cfb3a67238d
regex: avoid glibc deadlock during configure
glibc has a known bug where certain corruptions of the heap can
cause malloc to default to printing a debug message that includes
a backtrace, but the act of getting the backtrace uses dlopen
which in turn calls into malloc, causing a recursive lock ending
in deadlock. Thus, when configure is probing for a known glibc
heap corruption bug, the overall configure would hang.
The solution suggested by glibc developers is to force malloc
to quit printing debug messages, which avoids recursive malloc.
* m4/regex.m4 (gl_REGEX): Avoid recursive malloc deadlock when
glibc bug 15078 in turn triggers bug 16159.
Reported by Michal Privoznik.
Signed-off-by: Eric Blake <eblake@redhat.com>
author | Eric Blake <eblake@redhat.com> |
---|---|
date | Tue, 03 Dec 2013 10:34:13 -0700 |
parents | c741bc27922a |
children | 344018b6e5d7 |
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# strcasestr.m4 serial 21 dnl Copyright (C) 2005, 2007-2013 Free Software Foundation, Inc. dnl This file is free software; the Free Software Foundation dnl gives unlimited permission to copy and/or distribute it, dnl with or without modifications, as long as this notice is preserved. dnl Check that strcasestr is present and works. AC_DEFUN([gl_FUNC_STRCASESTR_SIMPLE], [ AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS]) dnl Persuade glibc <string.h> to declare strcasestr(). AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS]) AC_REQUIRE([gl_FUNC_MEMCHR]) AC_CHECK_FUNCS([strcasestr]) if test $ac_cv_func_strcasestr = no; then HAVE_STRCASESTR=0 else if test "$gl_cv_func_memchr_works" != yes; then REPLACE_STRCASESTR=1 else dnl Detect http://sourceware.org/bugzilla/show_bug.cgi?id=12092. AC_CACHE_CHECK([whether strcasestr works], [gl_cv_func_strcasestr_works_always], [AC_RUN_IFELSE([AC_LANG_PROGRAM([[ #include <string.h> /* for strcasestr */ #define P "_EF_BF_BD" #define HAYSTACK "F_BD_CE_BD" P P P P "_C3_88_20" P P P "_C3_A7_20" P #define NEEDLE P P P P P ]], [[return !!strcasestr (HAYSTACK, NEEDLE); ]])], [gl_cv_func_strcasestr_works_always=yes], [gl_cv_func_strcasestr_works_always=no], [dnl glibc 2.12 and cygwin 1.7.7 have a known bug. uClibc is not dnl affected, since it uses different source code for strcasestr dnl than glibc. dnl Assume that it works on all other platforms, even if it is not dnl linear. AC_EGREP_CPP([Lucky user], [ #ifdef __GNU_LIBRARY__ #include <features.h> #if ((__GLIBC__ == 2 && __GLIBC_MINOR__ > 12) || (__GLIBC__ > 2)) \ || defined __UCLIBC__ Lucky user #endif #elif defined __CYGWIN__ #include <cygwin/version.h> #if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 7) Lucky user #endif #else Lucky user #endif ], [gl_cv_func_strcasestr_works_always="guessing yes"], [gl_cv_func_strcasestr_works_always="guessing no"]) ]) ]) case "$gl_cv_func_strcasestr_works_always" in *yes) ;; *) REPLACE_STRCASESTR=1 ;; esac fi fi ]) # gl_FUNC_STRCASESTR_SIMPLE dnl Additionally, check that strcasestr is efficient. AC_DEFUN([gl_FUNC_STRCASESTR], [ AC_REQUIRE([gl_FUNC_STRCASESTR_SIMPLE]) if test $HAVE_STRCASESTR = 1 && test $REPLACE_STRCASESTR = 0; then AC_CACHE_CHECK([whether strcasestr works in linear time], [gl_cv_func_strcasestr_linear], [AC_RUN_IFELSE([AC_LANG_PROGRAM([[ #include <signal.h> /* for signal */ #include <string.h> /* for strcasestr */ #include <stdlib.h> /* for malloc */ #include <unistd.h> /* for alarm */ static void quit (int sig) { exit (sig + 128); } ]], [[ int result = 0; size_t m = 1000000; char *haystack = (char *) malloc (2 * m + 2); char *needle = (char *) malloc (m + 2); /* Failure to compile this test due to missing alarm is okay, since all such platforms (mingw) also lack strcasestr. */ signal (SIGALRM, quit); alarm (5); /* Check for quadratic performance. */ if (haystack && needle) { memset (haystack, 'A', 2 * m); haystack[2 * m] = 'B'; haystack[2 * m + 1] = 0; memset (needle, 'A', m); needle[m] = 'B'; needle[m + 1] = 0; if (!strcasestr (haystack, needle)) result |= 1; } return result; ]])], [gl_cv_func_strcasestr_linear=yes], [gl_cv_func_strcasestr_linear=no], [dnl Only glibc > 2.12 and cygwin > 1.7.7 are known to have a dnl strcasestr that works in linear time. AC_EGREP_CPP([Lucky user], [ #include <features.h> #ifdef __GNU_LIBRARY__ #if ((__GLIBC__ == 2 && __GLIBC_MINOR__ > 12) || (__GLIBC__ > 2)) \ && !defined __UCLIBC__ Lucky user #endif #endif #ifdef __CYGWIN__ #include <cygwin/version.h> #if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 7) Lucky user #endif #endif ], [gl_cv_func_strcasestr_linear="guessing yes"], [gl_cv_func_strcasestr_linear="guessing no"]) ]) ]) case "$gl_cv_func_strcasestr_linear" in *yes) ;; *) REPLACE_STRCASESTR=1 ;; esac fi ]) # gl_FUNC_STRCASESTR # Prerequisites of lib/strcasestr.c. AC_DEFUN([gl_PREREQ_STRCASESTR], [ : ])