X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Fstrstr.m4;h=33cd7a32f231fb605e9a67f38ed547d5eec64660;hb=1276a2c5f24c0c932426aca9c899fa524d2443f2;hp=3639131c71618f1821b86d6933c2177c7b696e96;hpb=1e4ece4ab9850fbfa88c9ec43ea518c7bc266792;p=gnulib.git

diff --git a/m4/strstr.m4 b/m4/strstr.m4
index 3639131c7..33cd7a32f 100644
--- a/m4/strstr.m4
+++ b/m4/strstr.m4
@@ -1,20 +1,130 @@
-# strstr.m4 serial 5
-dnl Copyright (C) 2002-2003, 2005 Free Software Foundation, Inc.
+# strstr.m4 serial 16
+dnl Copyright (C) 2008-2014 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_STRSTR],
+dnl Check that strstr works.
+AC_DEFUN([gl_FUNC_STRSTR_SIMPLE],
 [
-  dnl No known system has a strstr() function that works correctly in
-  dnl multibyte locales. Therefore we use our version always.
-  AC_LIBOBJ(strstr)
-  gl_PREREQ_STRSTR
-  REPLACE_STRSTR=1
-])
+  AC_REQUIRE([gl_HEADER_STRING_H_DEFAULTS])
+  AC_REQUIRE([gl_FUNC_MEMCHR])
+  if test "$gl_cv_func_memchr_works" != yes; then
+    REPLACE_STRSTR=1
+  else
+    dnl Detect http://sourceware.org/bugzilla/show_bug.cgi?id=12092.
+    AC_CACHE_CHECK([whether strstr works],
+      [gl_cv_func_strstr_works_always],
+      [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
+#include <string.h> /* for strstr */
+#define P "_EF_BF_BD"
+#define HAYSTACK "F_BD_CE_BD" P P P P "_C3_88_20" P P P "_C3_A7_20" P
+#define NEEDLE P P P P P
+]], [[return !!strstr (HAYSTACK, NEEDLE);
+    ]])],
+        [gl_cv_func_strstr_works_always=yes],
+        [gl_cv_func_strstr_works_always=no],
+        [dnl glibc 2.12 and cygwin 1.7.7 have a known bug.  uClibc is not
+         dnl affected, since it uses different source code for strstr than
+         dnl glibc.
+         dnl Assume that it works on all other platforms, even if it is not
+         dnl linear.
+         AC_EGREP_CPP([Lucky user],
+           [
+#ifdef __GNU_LIBRARY__
+ #include <features.h>
+ #if ((__GLIBC__ == 2 && __GLIBC_MINOR__ > 12) || (__GLIBC__ > 2)) \
+     || defined __UCLIBC__
+  Lucky user
+ #endif
+#elif defined __CYGWIN__
+ #include <cygwin/version.h>
+ #if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 7)
+  Lucky user
+ #endif
+#else
+  Lucky user
+#endif
+           ],
+           [gl_cv_func_strstr_works_always="guessing yes"],
+           [gl_cv_func_strstr_works_always="guessing no"])
+        ])
+      ])
+    case "$gl_cv_func_strstr_works_always" in
+      *yes) ;;
+      *)
+        REPLACE_STRSTR=1
+        ;;
+    esac
+  fi
+]) # gl_FUNC_STRSTR_SIMPLE
 
-# Prerequisites of lib/strstr.c.
-AC_DEFUN([gl_PREREQ_STRSTR], [
-  AC_REQUIRE([gl_FUNC_MBRTOWC])
-  :
-])
+dnl Additionally, check that strstr is efficient.
+AC_DEFUN([gl_FUNC_STRSTR],
+[
+  AC_REQUIRE([gl_FUNC_STRSTR_SIMPLE])
+  if test $REPLACE_STRSTR = 0; then
+    AC_CACHE_CHECK([whether strstr works in linear time],
+      [gl_cv_func_strstr_linear],
+      [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
+#include <signal.h> /* for signal */
+#include <string.h> /* for strstr */
+#include <stdlib.h> /* for malloc */
+#include <unistd.h> /* for alarm */
+static void quit (int sig) { exit (sig + 128); }
+]], [[
+    int result = 0;
+    size_t m = 1000000;
+    char *haystack = (char *) malloc (2 * m + 2);
+    char *needle = (char *) malloc (m + 2);
+    /* Failure to compile this test due to missing alarm is okay,
+       since all such platforms (mingw) also have quadratic strstr.  */
+    signal (SIGALRM, quit);
+    alarm (5);
+    /* Check for quadratic performance.  */
+    if (haystack && needle)
+      {
+        memset (haystack, 'A', 2 * m);
+        haystack[2 * m] = 'B';
+        haystack[2 * m + 1] = 0;
+        memset (needle, 'A', m);
+        needle[m] = 'B';
+        needle[m + 1] = 0;
+        if (!strstr (haystack, needle))
+          result |= 1;
+      }
+    return result;
+    ]])],
+        [gl_cv_func_strstr_linear=yes], [gl_cv_func_strstr_linear=no],
+        [dnl Only glibc > 2.12 on processors without SSE 4.2 instructions and
+         dnl cygwin > 1.7.7 are known to have a bug-free strstr that works in
+         dnl linear time.
+         AC_EGREP_CPP([Lucky user],
+           [
+#include <features.h>
+#ifdef __GNU_LIBRARY__
+ #if ((__GLIBC__ == 2 && __GLIBC_MINOR__ > 12) || (__GLIBC__ > 2)) \
+     && !(defined __i386__ || defined __x86_64__) \
+     && !defined __UCLIBC__
+  Lucky user
+ #endif
+#endif
+#ifdef __CYGWIN__
+ #include <cygwin/version.h>
+ #if CYGWIN_VERSION_DLL_COMBINED > CYGWIN_VERSION_DLL_MAKE_COMBINED (1007, 7)
+  Lucky user
+ #endif
+#endif
+           ],
+           [gl_cv_func_strstr_linear="guessing yes"],
+           [gl_cv_func_strstr_linear="guessing no"])
+        ])
+      ])
+    case "$gl_cv_func_strstr_linear" in
+      *yes) ;;
+      *)
+        REPLACE_STRSTR=1
+        ;;
+    esac
+  fi
+]) # gl_FUNC_STRSTR