X-Git-Url: http://erislabs.net/gitweb/?a=blobdiff_plain;f=lib%2Fstrstr.c;h=265fc8533ac0d9ea7b9dd24a1230556301ecc348;hb=a731808a4ac512228e870d5f443b91557f418559;hp=77f24cbc93b7a50bbbb7419b187f2ebc0ae0143e;hpb=f49cdb3fcfccab4b4e56f08aa00b7df561951662;p=gnulib.git

diff --git a/lib/strstr.c b/lib/strstr.c
index 77f24cbc9..265fc8533 100644
--- a/lib/strstr.c
+++ b/lib/strstr.c
@@ -1,5 +1,6 @@
-/* strstr.c -- return the offset of one string within another
-   Copyright (C) 1989, 1990 Free Software Foundation, Inc.
+/* Copyright (C) 1991, 1992, 1993, 1994, 1996, 1997, 1998, 2000, 2004, 2007,
+   2008, 2009, 2010 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
 
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
@@ -11,34 +12,72 @@
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.
 
-   You should have received a copy of the GNU General Public License
-   along with this program; if not, write to the Free Software Foundation,
-   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+   You should have received a copy of the GNU General Public License along
+   with this program; if not, write to the Free Software Foundation,
+   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
 
-/* Written by Mike Rendell <michael@cs.mun.ca>.  */
+/* This particular implementation was written by Eric Blake, 2008.  */
 
-/* Return the starting address of string S2 in S1;
-   return 0 if it is not found. */
+#ifndef _LIBC
+# include <config.h>
+#endif
 
+/* Specification of strstr.  */
+#include <string.h>
+
+#include <stdbool.h>
+
+#ifndef _LIBC
+# define __builtin_expect(expr, val)   (expr)
+#endif
+
+#define RETURN_TYPE char *
+#define AVAILABLE(h, h_l, j, n_l)                       \
+  (!memchr ((h) + (h_l), '\0', (j) + (n_l) - (h_l))     \
+   && ((h_l) = (j) + (n_l)))
+#include "str-two-way.h"
+
+/* Return the first occurrence of NEEDLE in HAYSTACK.  Return HAYSTACK
+   if NEEDLE is empty, otherwise NULL if NEEDLE is not found in
+   HAYSTACK.  */
 char *
-strstr (s1, s2)
-     char *s1;
-     char *s2;
+strstr (const char *haystack_start, const char *needle_start)
 {
-  int i;
-  char *p1;
-  char *p2;
-  char *s = s1;
-
-  for (p2 = s2, i = 0; *s; p2 = s2, i++, s++)
-    {
-      for (p1 = s; *p1 && *p2 && *p1 == *p2; p1++, p2++)
-	;
-      if (!*p2)
-	break;
-    }
-  if (!*p2)
-    return s1 + i;
-
-  return 0;
+  const char *haystack = haystack_start;
+  const char *needle = needle_start;
+  size_t needle_len; /* Length of NEEDLE.  */
+  size_t haystack_len; /* Known minimum length of HAYSTACK.  */
+  bool ok = true; /* True if NEEDLE is prefix of HAYSTACK.  */
+
+  /* Determine length of NEEDLE, and in the process, make sure
+     HAYSTACK is at least as long (no point processing all of a long
+     NEEDLE if HAYSTACK is too short).  */
+  while (*haystack && *needle)
+    ok &= *haystack++ == *needle++;
+  if (*needle)
+    return NULL;
+  if (ok)
+    return (char *) haystack_start;
+
+  /* Reduce the size of haystack using strchr, since it has a smaller
+     linear coefficient than the Two-Way algorithm.  */
+  needle_len = needle - needle_start;
+  haystack = strchr (haystack_start + 1, *needle_start);
+  if (!haystack || __builtin_expect (needle_len == 1, 0))
+    return (char *) haystack;
+  needle -= needle_len;
+  haystack_len = (haystack > haystack_start + needle_len ? 1
+                  : needle_len + haystack_start - haystack);
+
+  /* Perform the search.  Abstract memory is considered to be an array
+     of 'unsigned char' values, not an array of 'char' values.  See
+     ISO C 99 section 6.2.6.1.  */
+  if (needle_len < LONG_NEEDLE_THRESHOLD)
+    return two_way_short_needle ((const unsigned char *) haystack,
+                                 haystack_len,
+                                 (const unsigned char *) needle, needle_len);
+  return two_way_long_needle ((const unsigned char *) haystack, haystack_len,
+                              (const unsigned char *) needle, needle_len);
 }
+
+#undef LONG_NEEDLE_THRESHOLD