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/*
* gzip_decompress.c - decompress with a gzip wrapper
*
* Copyright 2016 Eric Biggers
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use,
* copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following
* conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*/
#include "lib_common.h"
#include "gzip_constants.h"
LIBDEFLATEAPI enum libdeflate_result
libdeflate_gzip_decompress_ex(struct libdeflate_decompressor *d,
const void *in, size_t in_nbytes,
void *out, size_t out_nbytes_avail,
size_t *actual_in_nbytes_ret,
size_t *actual_out_nbytes_ret)
{
const u8 *in_next = in;
const u8 * const in_end = in_next + in_nbytes;
u8 flg;
size_t actual_in_nbytes;
size_t actual_out_nbytes;
enum libdeflate_result result;
if (in_nbytes < GZIP_MIN_OVERHEAD)
return LIBDEFLATE_BAD_DATA;
/* ID1 */
if (*in_next++ != GZIP_ID1)
return LIBDEFLATE_BAD_DATA;
/* ID2 */
if (*in_next++ != GZIP_ID2)
return LIBDEFLATE_BAD_DATA;
/* CM */
if (*in_next++ != GZIP_CM_DEFLATE)
return LIBDEFLATE_BAD_DATA;
flg = *in_next++;
/* MTIME */
in_next += 4;
/* XFL */
in_next += 1;
/* OS */
in_next += 1;
if (flg & GZIP_FRESERVED)
return LIBDEFLATE_BAD_DATA;
/* Extra field */
if (flg & GZIP_FEXTRA) {
u16 xlen = get_unaligned_le16(in_next);
in_next += 2;
if (in_end - in_next < (u32)xlen + GZIP_FOOTER_SIZE)
return LIBDEFLATE_BAD_DATA;
in_next += xlen;
}
/* Original file name (zero terminated) */
if (flg & GZIP_FNAME) {
while (*in_next++ != 0 && in_next != in_end)
;
if (in_end - in_next < GZIP_FOOTER_SIZE)
return LIBDEFLATE_BAD_DATA;
}
/* File comment (zero terminated) */
if (flg & GZIP_FCOMMENT) {
while (*in_next++ != 0 && in_next != in_end)
;
if (in_end - in_next < GZIP_FOOTER_SIZE)
return LIBDEFLATE_BAD_DATA;
}
/* CRC16 for gzip header */
if (flg & GZIP_FHCRC) {
in_next += 2;
if (in_end - in_next < GZIP_FOOTER_SIZE)
return LIBDEFLATE_BAD_DATA;
}
/* Compressed data */
result = libdeflate_deflate_decompress_ex(d, in_next,
in_end - GZIP_FOOTER_SIZE - in_next,
out, out_nbytes_avail,
&actual_in_nbytes,
actual_out_nbytes_ret);
if (result != LIBDEFLATE_SUCCESS)
return result;
if (actual_out_nbytes_ret)
actual_out_nbytes = *actual_out_nbytes_ret;
else
actual_out_nbytes = out_nbytes_avail;
in_next += actual_in_nbytes;
/* CRC32 */
if (libdeflate_crc32(0, out, actual_out_nbytes) !=
get_unaligned_le32(in_next))
return LIBDEFLATE_BAD_DATA;
in_next += 4;
/* ISIZE */
if ((u32)actual_out_nbytes != get_unaligned_le32(in_next))
return LIBDEFLATE_BAD_DATA;
in_next += 4;
if (actual_in_nbytes_ret)
*actual_in_nbytes_ret = in_next - (u8 *)in;
return LIBDEFLATE_SUCCESS;
}
LIBDEFLATEAPI enum libdeflate_result
libdeflate_gzip_decompress(struct libdeflate_decompressor *d,
const void *in, size_t in_nbytes,
void *out, size_t out_nbytes_avail,
size_t *actual_out_nbytes_ret)
{
return libdeflate_gzip_decompress_ex(d, in, in_nbytes,
out, out_nbytes_avail,
NULL, actual_out_nbytes_ret);
}
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