maint: update copyright

[gnulib.git] / lib / strstr.c

diff --git a/lib/strstr.c b/lib/strstr.c
index 6c67d9f..32a2be0 100644 (file)
--- 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) 1991-1994, 1996-1998, 2000, 2004, 2007-2014 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
@@ -11,39 +12,71 @@
    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., 675 Mass Ave, Cambridge, MA 02139, USA.  */
+   You should have received a copy of the GNU General Public License along
+   with this program; if not, see <http://www.gnu.org/licenses/>.  */
 
-/* Author:
-       Mike Rendell                    Department of Computer Science
-       michael@garfield.mun.edu        Memorial University of Newfoundland
-       ..!uunet!garfield!michael       St. John's, Nfld., Canada
-       (709) 737-4550                  A1C 5S7
-*/
+/* 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