56 lines
2.8 KiB
C
56 lines
2.8 KiB
C
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/*-*- 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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│ This program is free software; you can redistribute it and/or modify │
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│ it under the terms of the GNU General Public License as published by │
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│ the Free Software Foundation; version 2 of the License. │
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│ │
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│ This program is distributed in the hope that it will be useful, but │
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│ WITHOUT ANY WARRANTY; without even the implied warranty of │
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│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │
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│ General Public License for more details. │
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│ │
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│ You should have received a copy of the GNU General Public License │
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│ along with this program; if not, write to the Free Software │
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│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │
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│ 02110-1301 USA │
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╚─────────────────────────────────────────────────────────────────────────────*/
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#include "libc/str/str.h"
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/**
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* Copies at most 𝑛 bytes from 𝑠 to 𝑑 until 𝑐 is encountered.
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*
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* This is little-known C Standard Library approach, dating back to the
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* Fourth Edition of System Five, for copying a C strings to fixed-width
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* buffers, with added generality.
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*
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* For example, strictly:
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*
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* char buf[16];
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* CHECK_NOTNULL(memccpy(buf, s, '\0', sizeof(buf)));
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*
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* Or unstrictly:
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*
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* if (!memccpy(buf, s, '\0', sizeof(buf))) strcpy(buf, "?");
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*
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* Are usually more sensible than the following:
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*
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* char cstrbuf[16];
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* snprintf(cstrbuf, sizeof(cstrbuf), "%s", CSTR);
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*
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* @return 𝑑 + idx(𝑐) + 1, or NULL if 𝑐 ∉ 𝑠₀․․ₙ₋₁
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* @note 𝑑 and 𝑠 can't overlap
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* @asyncsignalsafe
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*/
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void *memccpy(void *d, const void *s, int c, size_t n) {
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const char *p, *pe;
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if ((pe = memchr((p = s), c, n))) {
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return mempcpy(d, s, pe - p + 1);
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} else {
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memcpy(d, s, n);
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return NULL;
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}
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}
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