-# memmem.m4 serial 2
-dnl Copyright (C) 2002, 2003, 2004 Free Software Foundation, Inc.
+# memmem.m4 serial 24
+dnl Copyright (C) 2002-2004, 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.
-AC_DEFUN([gl_FUNC_MEMMEM],
+dnl Check that memmem is present and functional.
+AC_DEFUN([gl_FUNC_MEMMEM_SIMPLE],
[
dnl Persuade glibc <string.h> to declare memmem().
- AC_REQUIRE([AC_GNU_SOURCE])
+ AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])
- AC_REPLACE_FUNCS(memmem)
- AC_CHECK_DECLS_ONCE(memmem)
+ AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
+ AC_CHECK_FUNCS([memmem])
+ if test $ac_cv_func_memmem = yes; then
+ HAVE_MEMMEM=1
+ else
+ HAVE_MEMMEM=0
+ fi
+ AC_CHECK_DECLS_ONCE([memmem])
+ if test $ac_cv_have_decl_memmem = no; then
+ HAVE_DECL_MEMMEM=0
+ else
+ dnl Detect http://sourceware.org/bugzilla/show_bug.cgi?id=12092.
+ dnl Also check that we handle empty needles correctly.
+ AC_CACHE_CHECK([whether memmem works],
+ [gl_cv_func_memmem_works_always],
+ [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
+#include <string.h> /* for memmem */
+#define P "_EF_BF_BD"
+#define HAYSTACK "F_BD_CE_BD" P P P P "_C3_88_20" P P P "_C3_A7_20" P
+#define NEEDLE P P P P P
+]], [[
+ int result = 0;
+ if (memmem (HAYSTACK, strlen (HAYSTACK), NEEDLE, strlen (NEEDLE)))
+ result |= 1;
+ /* Check for empty needle behavior. */
+ {
+ const char *haystack = "AAA";
+ if (memmem (haystack, 3, NULL, 0) != haystack)
+ result |= 2;
+ }
+ return result;
+ ]])],
+ [gl_cv_func_memmem_works_always=yes],
+ [gl_cv_func_memmem_works_always=no],
+ [dnl glibc 2.9..2.12 and cygwin 1.7.7 have issue #12092 above.
+ dnl Also empty needles work on glibc >= 2.1 and cygwin >= 1.7.0.
+ dnl uClibc is not affected, since it uses different source code.
+ dnl Assume that it works on all other platforms (even if not linear).
+ AC_EGREP_CPP([Lucky user],
+ [
+#ifdef __GNU_LIBRARY__
+ #include <features.h>
+ #if ((__GLIBC__ == 2 && ((__GLIBC_MINOR > 0 && __GLIBC_MINOR__ < 9) \
+ || __GLIBC_MINOR__ > 12)) \
+ || (__GLIBC__ > 2)) \
+ || defined __UCLIBC__
+ Lucky user
+ #endif
+#elif defined __CYGWIN__
+ #include <cygwin/version.h>
+ #if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 7)
+ Lucky user
+ #endif
+#else
+ Lucky user
+#endif
+ ],
+ [gl_cv_func_memmem_works_always="guessing yes"],
+ [gl_cv_func_memmem_works_always="guessing no"])
+ ])
+ ])
+ case "$gl_cv_func_memmem_works_always" in
+ *yes) ;;
+ *)
+ REPLACE_MEMMEM=1
+ ;;
+ esac
+ fi
gl_PREREQ_MEMMEM
-])
+]) # gl_FUNC_MEMMEM_SIMPLE
+
+dnl Additionally, check that memmem has linear performance characteristics
+AC_DEFUN([gl_FUNC_MEMMEM],
+[
+ AC_REQUIRE([gl_FUNC_MEMMEM_SIMPLE])
+ if test $HAVE_DECL_MEMMEM = 1 && test $REPLACE_MEMMEM = 0; then
+ AC_CACHE_CHECK([whether memmem works in linear time],
+ [gl_cv_func_memmem_works_fast],
+ [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
+#include <signal.h> /* for signal */
+#include <string.h> /* for memmem */
+#include <stdlib.h> /* for malloc */
+#include <unistd.h> /* for alarm */
+static void quit (int sig) { exit (sig + 128); }
+]], [[
+ int result = 0;
+ size_t m = 1000000;
+ char *haystack = (char *) malloc (2 * m + 1);
+ char *needle = (char *) malloc (m + 1);
+ /* Failure to compile this test due to missing alarm is okay,
+ since all such platforms (mingw) also lack memmem. */
+ signal (SIGALRM, quit);
+ alarm (5);
+ /* Check for quadratic performance. */
+ if (haystack && needle)
+ {
+ memset (haystack, 'A', 2 * m);
+ haystack[2 * m] = 'B';
+ memset (needle, 'A', m);
+ needle[m] = 'B';
+ if (!memmem (haystack, 2 * m + 1, needle, m + 1))
+ result |= 1;
+ }
+ return result;
+ ]])],
+ [gl_cv_func_memmem_works_fast=yes], [gl_cv_func_memmem_works_fast=no],
+ [dnl Only glibc >= 2.9 and cygwin > 1.7.0 are known to have a
+ dnl memmem that works in linear time.
+ AC_EGREP_CPP([Lucky user],
+ [
+#include <features.h>
+#ifdef __GNU_LIBRARY__
+ #if ((__GLIBC__ == 2 && __GLIBC_MINOR__ >= 9) || (__GLIBC__ > 2)) \
+ && !defined __UCLIBC__
+ Lucky user
+ #endif
+#endif
+#ifdef __CYGWIN__
+ #include <cygwin/version.h>
+ #if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 0)
+ Lucky user
+ #endif
+#endif
+ ],
+ [gl_cv_func_memmem_works_fast="guessing yes"],
+ [gl_cv_func_memmem_works_fast="guessing no"])
+ ])
+ ])
+ case "$gl_cv_func_memmem_works_fast" in
+ *yes) ;;
+ *)
+ REPLACE_MEMMEM=1
+ ;;
+ esac
+ fi
+]) # gl_FUNC_MEMMEM
# Prerequisites of lib/memmem.c.
AC_DEFUN([gl_PREREQ_MEMMEM], [:])
projects / gnulib.git / blobdiff