1 /*
2 * zlib_decompress.c - decompress with a zlib wrapper
3 *
4 * Originally public domain; changes after 2016-09-07 are copyrighted.
5 *
6 * Copyright 2016 Eric Biggers
7 *
8 * Permission is hereby granted, free of charge, to any person
9 * obtaining a copy of this software and associated documentation
10 * files (the "Software"), to deal in the Software without
11 * restriction, including without limitation the rights to use,
12 * copy, modify, merge, publish, distribute, sublicense, and/or sell
13 * copies of the Software, and to permit persons to whom the
14 * Software is furnished to do so, subject to the following
15 * conditions:
16 *
17 * The above copyright notice and this permission notice shall be
18 * included in all copies or substantial portions of the Software.
19 *
20 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
21 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
22 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
23 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
24 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
25 * WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
26 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
27 * OTHER DEALINGS IN THE SOFTWARE.
28 */
29
30 #include "unaligned.h"
31 #include "zlib_constants.h"
32
33 #include "libdeflate.h"
34
35 LIBDEFLATEAPI enum libdeflate_result
libdeflate_zlib_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)36 libdeflate_zlib_decompress(struct libdeflate_decompressor *d,
37 const void *in, size_t in_nbytes,
38 void *out, size_t out_nbytes_avail,
39 size_t *actual_out_nbytes_ret)
40 {
41 const u8 *in_next = in;
42 const u8 * const in_end = in_next + in_nbytes;
43 u16 hdr;
44 size_t actual_out_nbytes;
45 enum libdeflate_result result;
46
47 if (in_nbytes < ZLIB_MIN_OVERHEAD)
48 return LIBDEFLATE_BAD_DATA;
49
50 /* 2 byte header: CMF and FLG */
51 hdr = get_unaligned_be16(in_next);
52 in_next += 2;
53
54 /* FCHECK */
55 if ((hdr % 31) != 0)
56 return LIBDEFLATE_BAD_DATA;
57
58 /* CM */
59 if (((hdr >> 8) & 0xF) != ZLIB_CM_DEFLATE)
60 return LIBDEFLATE_BAD_DATA;
61
62 /* CINFO */
63 if ((hdr >> 12) > ZLIB_CINFO_32K_WINDOW)
64 return LIBDEFLATE_BAD_DATA;
65
66 /* FDICT */
67 if ((hdr >> 5) & 1)
68 return LIBDEFLATE_BAD_DATA;
69
70 /* Compressed data */
71 result = libdeflate_deflate_decompress(d, in_next,
72 in_end - ZLIB_FOOTER_SIZE - in_next,
73 out, out_nbytes_avail,
74 actual_out_nbytes_ret);
75 if (result != LIBDEFLATE_SUCCESS)
76 return result;
77
78 if (actual_out_nbytes_ret)
79 actual_out_nbytes = *actual_out_nbytes_ret;
80 else
81 actual_out_nbytes = out_nbytes_avail;
82
83 in_next = in_end - ZLIB_FOOTER_SIZE;
84
85 /* ADLER32 */
86 if (libdeflate_adler32(1, out, actual_out_nbytes) !=
87 get_unaligned_be32(in_next))
88 return LIBDEFLATE_BAD_DATA;
89
90 return LIBDEFLATE_SUCCESS;
91 }
92