mirror of
https://github.com/jart/cosmopolitan.git
synced 2025-02-07 23:13:34 +00:00
51 lines
2.9 KiB
C
51 lines
2.9 KiB
C
/*-*- 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/zip.h"
|
|
|
|
/**
|
|
* Locates End Of Central Directory record in ZIP file.
|
|
*
|
|
* We search backwards for the End Of Central Directory Record magnum.
|
|
* The ZIP spec says this can be anywhere in the last 64kb. We go all
|
|
* the way since .com.dbg binaries will have lots of DWARF stuff after
|
|
* the embedded .com binary. As such, we sanity check the other fields
|
|
* too to make sure the record seems legit and it's not just a random
|
|
* occurrence of the magnum.
|
|
*
|
|
* @param p points to file memory
|
|
* @param n is byte size of file
|
|
*/
|
|
uint8_t *zipfindcentraldir(const uint8_t *p, size_t n) {
|
|
size_t i;
|
|
if (n >= kZipCdirHdrMinSize) {
|
|
i = n - kZipCdirHdrMinSize;
|
|
do {
|
|
if (ZIP_CDIR_MAGIC(p + i) == kZipCdirHdrMagic &&
|
|
i + ZIP_CDIR_HDRSIZE(p + i) <= n &&
|
|
ZIP_CDIR_DISK(p + i) == ZIP_CDIR_STARTINGDISK(p + i) &&
|
|
ZIP_CDIR_RECORDSONDISK(p + i) == ZIP_CDIR_RECORDS(p + i) &&
|
|
ZIP_CDIR_RECORDS(p + i) * kZipCdirHdrMinSize <=
|
|
ZIP_CDIR_SIZE(p + i) &&
|
|
ZIP_CDIR_OFFSET(p + i) + ZIP_CDIR_SIZE(p + i) <= i) {
|
|
return (/*unconst*/ uint8_t *)(p + i);
|
|
}
|
|
} while (i--);
|
|
}
|
|
return NULL;
|
|
}
|