From 758f820bcc0f68aeebac1717e537ca13a320b909 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Sun, 7 Apr 2024 18:11:47 +0200 Subject: Adding upstream version 9.1. Signed-off-by: Daniel Baumann --- lib/strstr.c | 78 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 78 insertions(+) create mode 100644 lib/strstr.c (limited to 'lib/strstr.c') diff --git a/lib/strstr.c b/lib/strstr.c new file mode 100644 index 0000000..6236915 --- /dev/null +++ b/lib/strstr.c @@ -0,0 +1,78 @@ +/* Copyright (C) 1991-1994, 1996-1998, 2000, 2004, 2007-2022 Free Software + Foundation, Inc. + This file is part of the GNU C Library. + + This file 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 2.1 of the + License, or (at your option) any later version. + + This file 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 . */ + +/* This particular implementation was written by Eric Blake, 2008. */ + +#ifndef _LIBC +# include +#endif + +/* Specification of strstr. */ +#include + +#include + +#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 -- cgit v1.2.3