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45 lines
2.5 KiB
C
45 lines
2.5 KiB
C
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
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│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
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╞══════════════════════════════════════════════════════════════════════════════╡
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│ Copyright 2020 Justine Alexandra Roberts Tunney │
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│ │
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│ Permission to use, copy, modify, and/or distribute this software for │
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│ any purpose with or without fee is hereby granted, provided that the │
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│ above copyright notice and this permission notice appear in all copies. │
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│ │
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│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
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│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
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│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
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│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
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│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
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│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
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│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
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│ PERFORMANCE OF THIS SOFTWARE. │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/bits/safemacros.internal.h"
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#include "libc/str/str.h"
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/**
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* Searches for substring.
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*
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* @param haystack is the search area, as a NUL-terminated string
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* @param needle is the desired substring, also NUL-terminated
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* @return pointer to first substring within haystack, or NULL
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* @asyncsignalsafe
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* @see memmem()
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*/
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char *strstr(const char *haystack, const char *needle) {
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size_t i;
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if (!*needle) return haystack;
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haystack = firstnonnull(strchr(haystack, *needle), haystack);
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for (;;) {
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for (i = 0;;) {
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if (!needle[i]) return (/*unconst*/ char *)haystack;
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if (!haystack[i]) break;
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if (needle[i] != haystack[i]) break;
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++i;
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}
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if (!*haystack++) break;
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}
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return NULL;
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}
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