/* Return the offset of one string within another.
- Copyright (C) 1994,1996,1997,2000,2001,2003 Free Software Foundation, Inc.
+ Copyright (C) 1994-2015 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
- License along with the GNU C Library; if not, write to the Free
- Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
- 02111-1307 USA. */
-
-/*
- * My personal strstr() implementation that beats most other algorithms.
- * Until someone tells me otherwise, I assume that this is the
- * fastest implementation of strstr() in C.
- * I deliberately chose not to comment it. You should have at least
- * as much fun trying to understand it, as I had to write it :-).
- *
- * Stephen R. van den Berg, berg@pool.informatik.rwth-aachen.de */
-
-#if HAVE_CONFIG_H
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+/* This particular implementation was written by Eric Blake, 2008. */
+
+#ifndef _LIBC
# include <config.h>
#endif
-#if defined _LIBC || defined HAVE_STRING_H
-# include <string.h>
+/* Specification of strstr. */
+#include <string.h>
+
+#include <stdbool.h>
+
+#ifndef _LIBC
+# define __builtin_expect(expr, val) (expr)
#endif
-typedef unsigned chartype;
+#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)))
+#define CHECK_EOL (1)
+#define RET0_IF_0(a) if (!a) goto ret0
+#include "str-two-way.h"
#undef strstr
+#ifndef STRSTR
+#define STRSTR strstr
+#endif
+
+/* 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 (phaystack, pneedle)
- const char *phaystack;
- const char *pneedle;
+STRSTR (const char *haystack_start, const char *needle_start)
{
- const unsigned char *haystack, *needle;
- chartype b;
- const unsigned char *rneedle;
-
- haystack = (const unsigned char *) phaystack;
-
- if ((b = *(needle = (const unsigned char *) pneedle)))
- {
- chartype c;
- haystack--; /* possible ANSI violation */
-
- {
- chartype a;
- do
- if (!(a = *++haystack))
- goto ret0;
- while (a != b);
- }
-
- if (!(c = *++needle))
- goto foundneedle;
- ++needle;
- goto jin;
-
- for (;;)
- {
- {
- chartype a;
- if (0)
- jin:{
- if ((a = *++haystack) == c)
- goto crest;
- }
- else
- a = *++haystack;
- do
- {
- for (; a != b; a = *++haystack)
- {
- if (!a)
- goto ret0;
- if ((a = *++haystack) == b)
- break;
- if (!a)
- goto ret0;
- }
- }
- while ((a = *++haystack) != c);
- }
- crest:
- {
- chartype a;
- {
- const unsigned char *rhaystack;
- if (*(rhaystack = haystack-- + 1) == (a = *(rneedle = needle)))
- do
- {
- if (!a)
- goto foundneedle;
- if (*++rhaystack != (a = *++needle))
- break;
- if (!a)
- goto foundneedle;
- }
- while (*++rhaystack == (a = *++needle));
- needle = rneedle; /* took the register-poor aproach */
- }
- if (!a)
- break;
- }
- }
- }
-foundneedle:
- return (char *) haystack;
-ret0:
- 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);
}
libc_hidden_builtin_def (strstr)
+
+#undef LONG_NEEDLE_THRESHOLD
projects / platform / upstream / glibc.git / blobdiff