cosmopolitan/libc/str/lz4check.c

34 lines
2.3 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/nexgen32e/kompressor.h"
#include "libc/nexgen32e/lz4.h"
const unsigned char *lz4check(const void *data) {
const unsigned char *frame = data;
if (LZ4_MAGIC(frame) == LZ4_MAGICNUMBER && LZ4_FRAME_VERSION(frame) == 1 &&
LZ4_FRAME_BLOCKINDEPENDENCE(frame) == true &&
LZ4_FRAME_BLOCKCONTENTSIZEFLAG(frame) == true &&
LZ4_FRAME_RESERVED1(frame) == 0 && LZ4_FRAME_RESERVED2(frame) == 0 &&
LZ4_FRAME_RESERVED3(frame) == 0) {
return frame;
} else {
return NULL;
}
}