X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=m4%2Fstrstr.m4;h=f48bebb6dd143cec4d890caa28bb05b0d2d5fa0f;hb=8eaac7a51d093dbcecc0c2b42a5762a882b4517b;hp=5a49b07c2c4abcbf220e60386fa94b41c89e9e23;hpb=b6d1202a37101d586919b49c8d0531b5bb56d4a3;p=gnulib.git

diff --git a/m4/strstr.m4 b/m4/strstr.m4
index 5a49b07c2..f48bebb6d 100644
--- a/m4/strstr.m4
+++ b/m4/strstr.m4
@@ -1,4 +1,4 @@
-# strstr.m4 serial 2
+# strstr.m4 serial 5
 dnl Copyright (C) 2008 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -11,6 +11,7 @@ AC_DEFUN([gl_FUNC_STRSTR],
   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 memmem */
 #include <stdlib.h> /* for malloc */
 #include <unistd.h> /* for alarm */
@@ -20,6 +21,7 @@ AC_DEFUN([gl_FUNC_STRSTR],
     void *result = 0;
     /* Failure to compile this test due to missing alarm is okay,
        since all such platforms (mingw) also have quadratic strstr.  */
+    signal (SIGALRM, SIG_DFL);
     alarm (5);
     /* Check for quadratic performance.  */
     if (haystack && needle)
@@ -34,9 +36,27 @@ AC_DEFUN([gl_FUNC_STRSTR],
       }
     return !result;]])],
       [gl_cv_func_strstr_linear=yes], [gl_cv_func_strstr_linear=no],
-      [dnl pessimistically assume the worst, since even glibc 2.6.1
-       dnl has quadratic complexity in its strstr
-       gl_cv_func_strstr_linear="guessing no"])])
+      [dnl Only glibc >= 2.9 and cygwin >= 1.7.0 are known to have a
+       dnl strstr 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_strstr_linear=yes],
+	 [gl_cv_func_strstr_linear="guessing no"])
+      ])
+    ])
   if test "$gl_cv_func_strstr_linear" != yes; then
     REPLACE_STRSTR=1
     AC_LIBOBJ([strstr])