-/* 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
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