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author | Manuel A. Fernandez Montecelo <manuel.montezelo@gmail.com> | 2016-05-27 14:35:40 +0100 |
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committer | Manuel A. Fernandez Montecelo <manuel.montezelo@gmail.com> | 2016-05-27 14:35:40 +0100 |
commit | b1de003dac299705a7f01c997d2b866bafe39926 (patch) | |
tree | 1cc16a3877e945116387a380f7f3023f81fa36e4 /lib/strstr.c | |
parent | 752fd7247bc223bcea35bd89cf56d1c08ead9ba6 (diff) | |
parent | 3590c846d4c2febbc05b4ad6b14a06edc549e453 (diff) |
Merge tag 'upstream/0.9.6+really0.9.6'
Upstream version 0.9.6+really0.9.6
Diffstat (limited to 'lib/strstr.c')
-rw-r--r-- | lib/strstr.c | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/lib/strstr.c b/lib/strstr.c new file mode 100644 index 0000000..3aa05b5 --- /dev/null +++ b/lib/strstr.c @@ -0,0 +1,82 @@ +/* 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 |