mirror of
https://github.com/jart/cosmopolitan.git
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59 lines
3.2 KiB
C
59 lines
3.2 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/runtime/zipos.internal.h"
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// normalizes zip filesystem path w/ overlapping strlcpy() style api
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// zip paths look like relative paths, but they're actually absolute
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// with respect to the archive; so similar to how /../etc would mean
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// /etc, we'd translate that here to "etc", and "etc/" slash is kept
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// returns strlen of 𝑑; returns 𝑛 when insufficient buffer available
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// nul terminator is guaranteed if n>0. it's fine if 𝑑 and 𝑠 overlap
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// test vectors for this algorithm in: test/libc/stdio/zipdir_test.c
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size_t __zipos_normpath(char *d, const char *s, size_t n) {
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char *p, *e;
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for (p = d, e = d + n; p < e && *s; ++s) {
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if ((p == d || p[-1] == '/') && *s == '/') {
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// matched "^/" or "//"
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} else if ((p == d || p[-1] == '/') && //
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s[0] == '.' && //
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(!s[1] || s[1] == '/')) {
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// matched "/./" or "^.$" or "^./" or "/.$"
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s += !!s[1];
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} else if ((p == d || p[-1] == '/') && //
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s[0] == '.' && //
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s[1] == '.' && //
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(!s[2] || s[2] == '/')) {
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// matched "/../" or "^..$" or "^../" or "/..$"
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while (p > d && p[-1] == '/') --p;
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while (p > d && p[-1] != '/') --p;
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} else {
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*p++ = *s;
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}
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}
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// if we didn't overflow
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if (p < e) {
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*p = '\0';
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} else {
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// force nul-terminator to exist if possible
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if (p > d) {
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p[-1] = '\0';
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}
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}
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return p - d;
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}
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