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authorManuel A. Fernandez Montecelo <manuel.montezelo@gmail.com>2016-05-26 16:48:15 +0100
committerManuel A. Fernandez Montecelo <manuel.montezelo@gmail.com>2016-05-26 16:48:15 +0100
commit5f2b09982312c98863eb9a8dfe2c608b81f58259 (patch)
treee5d38581c2f36e1cca02efedd2d85044d77f76f9 /lib/strstr.c
parent3e0814cd9862b89c7a39672672937477bd87ddfb (diff)
Imported Upstream version 0.9.6upstream/0.9.6
Diffstat (limited to 'lib/strstr.c')
-rw-r--r--lib/strstr.c82
1 files changed, 82 insertions, 0 deletions
diff --git a/lib/strstr.c b/lib/strstr.c
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+/* Copyright (C) 1991-1994, 1996-1998, 2000, 2004, 2007-2015 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 Lesser General Public License as published by
+ the Free Software Foundation; either version 2, or (at your option)
+ any later version.
+
+ This program is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License along
+ with this program; if not, see <http://www.gnu.org/licenses/>. */
+
+/* This particular implementation was written by Eric Blake, 2008. */
+
+#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 (const char *haystack_start, const char *needle_start)
+{
+ 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