X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Fstrcasestr.m4;h=6e940bcb6d4a0df69048c8fa017303cef246d373;hb=3ac9b4577c78342bdd022b31cf56de2b12f7297b;hp=92a0f1554cad339613b22fb59ab5e7f94824b70e;hpb=c16199ce77b7fe5aee147446944e9ea27b431caa;p=gnulib.git

diff --git a/m4/strcasestr.m4 b/m4/strcasestr.m4
index 92a0f1554..6e940bcb6 100644
--- a/m4/strcasestr.m4
+++ b/m4/strcasestr.m4
@@ -1,20 +1,95 @@
-# strcasestr.m4 serial 3
-dnl Copyright (C) 2005, 2007 Free Software Foundation, Inc.
+# strcasestr.m4 serial 13
+dnl Copyright (C) 2005, 2007, 2008, 2009, 2010 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
+    fi
+  fi
+  if test $HAVE_STRCASESTR = 0 || test $REPLACE_STRCASESTR = 1; then
+    AC_LIBOBJ([strcasestr])
+    gl_PREREQ_STRCASESTR
+  fi
+]) # gl_FUNC_STRCASESTR_SIMPLE
+
+dnl Additionally, check that strcasestr is efficient.
 AC_DEFUN([gl_FUNC_STRCASESTR],
 [
-  dnl No known system has a strcasestr() function that works correctly in
-  dnl multibyte locales. Therefore we use our version always.
-  AC_LIBOBJ(strcasestr)
-  REPLACE_STRCASESTR=1
-  gl_PREREQ_STRCASESTR
-])
+  AC_REQUIRE([gl_FUNC_STRCASESTR_SIMPLE])
+  if test $HAVE_STRCASESTR = 1 && test $REPLACE_STRCASESTR = 0; then
+    AC_CACHE_CHECK([whether strcasestr works in linear time],
+      [gl_cv_func_strcasestr_linear],
+      [AC_RUN_IFELSE([AC_LANG_PROGRAM([[
+#include <signal.h> /* for signal */
+#include <string.h> /* for memmem */
+#include <stdlib.h> /* for malloc */
+#include <unistd.h> /* for alarm */
+]], [[size_t m = 1000000;
+    char *haystack = (char *) malloc (2 * m + 2);
+    char *needle = (char *) malloc (m + 2);
+    void *result = 0;
+    /* Failure to compile this test due to missing alarm is okay,
+       since all such platforms (mingw) also lack strcasestr.  */
+    signal (SIGALRM, SIG_DFL);
+    alarm (5);
+    /* Check for quadratic performance.  */
+    if (haystack && needle)
+      {
+        memset (haystack, 'A', 2 * m);
+        haystack[2 * m] = 'B';
+        haystack[2 * m + 1] = 0;
+        memset (needle, 'A', m);
+        needle[m] = 'B';
+        needle[m + 1] = 0;
+        result = strcasestr (haystack, needle);
+      }
+    return !result;]])],
+        [gl_cv_func_strcasestr_linear=yes], [gl_cv_func_strcasestr_linear=no],
+        [dnl Only glibc >= 2.9 and cygwin >= 1.7.0 are known to have a
+         dnl strcasestr that works in linear time.
+         AC_EGREP_CPP([Lucky user],
+           [
+#include <features.h>
+#ifdef __GNU_LIBRARY__
+ #if (__GLIBC__ == 2 && __GLIBC_MINOR__ >= 9) || (__GLIBC__ > 2)
+  Lucky user
+ #endif
+#endif
+#ifdef __CYGWIN__
+ #include <cygwin/version.h>
+ #if CYGWIN_VERSION_DLL_MAJOR >= 1007
+  Lucky user
+ #endif
+#endif
+           ],
+           [gl_cv_func_strcasestr_linear=yes],
+           [gl_cv_func_strcasestr_linear="guessing no"])
+        ])
+      ])
+    if test "$gl_cv_func_strcasestr_linear" != yes; then
+      REPLACE_STRCASESTR=1
+      AC_LIBOBJ([strcasestr])
+      gl_PREREQ_STRCASESTR
+    fi
+  fi
+]) # gl_FUNC_STRCASESTR
 
 # Prerequisites of lib/strcasestr.c.
 AC_DEFUN([gl_PREREQ_STRCASESTR], [
-  AC_REQUIRE([gl_FUNC_MBRTOWC])
   :
 ])