mirror of
https://github.com/cuberite/libdeflate.git
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f2c3a5b4e9
* Bring in common headers and program code from xpack project * Move program code to programs/ * Move library code to lib/ * GNU89 and MSVC2010 compatibility * Other changes
116 lines
2.7 KiB
C
116 lines
2.7 KiB
C
/*
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* gzip_decompress.c - decompress with a gzip wrapper
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*
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* Written in 2014-2016 by Eric Biggers <ebiggers3@gmail.com>
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*
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* To the extent possible under law, the author(s) have dedicated all copyright
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* and related and neighboring rights to this software to the public domain
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* worldwide. This software is distributed without any warranty.
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*
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* You should have received a copy of the CC0 Public Domain Dedication along
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* with this software. If not, see
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* <http://creativecommons.org/publicdomain/zero/1.0/>.
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*/
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#include "crc32.h"
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#include "gzip_constants.h"
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#include "unaligned.h"
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#include "libdeflate.h"
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LIBEXPORT enum decompress_result
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gzip_decompress(struct deflate_decompressor *d,
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const void *in, size_t in_nbytes,
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void *out, size_t out_nbytes_avail,
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size_t *actual_out_nbytes_ret)
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{
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const u8 *in_next = in;
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const u8 * const in_end = in_next + in_nbytes;
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u8 flg;
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size_t actual_out_nbytes;
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enum decompress_result result;
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if (in_nbytes < GZIP_MIN_OVERHEAD)
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return DECOMPRESS_BAD_DATA;
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/* ID1 */
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if (*in_next++ != GZIP_ID1)
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return DECOMPRESS_BAD_DATA;
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/* ID2 */
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if (*in_next++ != GZIP_ID2)
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return DECOMPRESS_BAD_DATA;
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/* CM */
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if (*in_next++ != GZIP_CM_DEFLATE)
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return DECOMPRESS_BAD_DATA;
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flg = *in_next++;
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/* MTIME */
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in_next += 4;
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/* XFL */
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in_next += 1;
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/* OS */
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in_next += 1;
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if (flg & GZIP_FRESERVED)
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return DECOMPRESS_BAD_DATA;
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/* Extra field */
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if (flg & GZIP_FEXTRA) {
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u16 xlen = get_unaligned_le16(in_next);
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in_next += 2;
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if (in_end - in_next < (u32)xlen + GZIP_FOOTER_SIZE)
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return DECOMPRESS_BAD_DATA;
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in_next += xlen;
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}
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/* Original file name (zero terminated) */
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if (flg & GZIP_FNAME) {
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while (*in_next++ != 0 && in_next != in_end)
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;
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if (in_end - in_next < GZIP_FOOTER_SIZE)
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return DECOMPRESS_BAD_DATA;
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}
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/* File comment (zero terminated) */
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if (flg & GZIP_FCOMMENT) {
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while (*in_next++ != 0 && in_next != in_end)
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;
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if (in_end - in_next < GZIP_FOOTER_SIZE)
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return DECOMPRESS_BAD_DATA;
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}
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/* CRC16 for gzip header */
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if (flg & GZIP_FHCRC) {
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in_next += 2;
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if (in_end - in_next < GZIP_FOOTER_SIZE)
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return DECOMPRESS_BAD_DATA;
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}
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/* Compressed data */
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result = deflate_decompress(d, in_next,
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in_end - GZIP_FOOTER_SIZE - in_next,
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out, out_nbytes_avail,
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actual_out_nbytes_ret);
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if (result != DECOMPRESS_SUCCESS)
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return result;
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if (actual_out_nbytes_ret)
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actual_out_nbytes = *actual_out_nbytes_ret;
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else
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actual_out_nbytes = out_nbytes_avail;
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in_next = in_end - GZIP_FOOTER_SIZE;
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/* CRC32 */
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if (crc32_gzip(out, actual_out_nbytes) != get_unaligned_le32(in_next))
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return DECOMPRESS_BAD_DATA;
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in_next += 4;
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/* ISIZE */
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if ((u32)actual_out_nbytes != get_unaligned_le32(in_next))
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return DECOMPRESS_BAD_DATA;
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return DECOMPRESS_SUCCESS;
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}
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