cosmopolitan/libc/runtime/zipos-normpath.c
Justine Tunney ebf784d4f5
Make improvements
- Introduce ualarm() function
- Make rename() report EISEMPTY on Windows
- Always raise EINVAL upon open(O_RDONLY|O_TRUNC)
- Add macro so ./configure will detect SOCK_CLOEXEC
- Fix O_TRUNC without O_CREAT not working on Windows
- Let fcntl(F_SETFL) change O_APPEND status on Windows
- Make sure pwrite() / pread() report ESPIPE on sockets
- Raise ESPIPE on Windows when pwrite() is used on pipe
- Properly compute O_APPEND CreateFile() flags on Windows
- Don't require O_DIRECTORY to open directories on Windows
- Fix more instances of Windows reporting EISDIR and ENOTDIR
- Normalize EFTYPE and EMLINK to ELOOP on NetBSD and FreeBSD
- Make unlink() / rmdir() work on read-only files on Windows
- Validate UTF-8 on Windows paths to fix bug with overlong NUL
- Always print signal name to stderr when crashing due to SIG_DFL
- Fix Windows bug where denormalized paths >260 chars didn't work
- Block signals on BSDs when thread exits before trashing its own stack
2023-08-21 02:34:17 -07:00

58 lines
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/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi│
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2020 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/runtime/zipos.internal.h"
// normalizes zip filesystem path w/ overlapping strlcpy() style api
// zip paths look like relative paths, but they're actually absolute
// with respect to the archive; so similar to how /../etc would mean
// /etc, we'd translate that here to "etc", and "etc/" slash is kept
// returns strlen of 𝑑; returns 𝑛 when insufficient buffer available
// nul terminator is guaranteed if n>0. it's fine if 𝑑 and 𝑠 overlap
// test vectors for this algorithm in: test/libc/stdio/zipdir_test.c
size_t __zipos_normpath(char *d, const char *s, size_t n) {
char *p, *e;
for (p = d, e = d + n; p < e && *s; ++s) {
if ((p == d || p[-1] == '/') && *s == '/') {
// matched "^/" or "//"
} else if ((p == d || p[-1] == '/') && //
s[0] == '.' && //
(!s[1] || s[1] == '/')) {
// matched "/./" or "^.$" or "^./" or "/.$"
} else if ((p == d || p[-1] == '/') && //
s[0] == '.' && //
s[1] == '.' && //
(!s[2] || s[2] == '/')) {
// matched "/../" or "^..$" or "^../" or "/..$"
while (p > d && p[-1] == '/') --p;
while (p > d && p[-1] != '/') --p;
} else {
*p++ = *s;
}
}
// if we didn't overflow
if (p < e) {
*p = '\0';
} else {
// force nul-terminator to exist if possible
if (p > d) {
p[-1] = '\0';
}
}
return p - d;
}