squashfs: fix use of uninitialised variable in zlib & xz decompressors
[linux-3.10.git] / fs / squashfs / zlib_wrapper.c
1 /*
2  * Squashfs - a compressed read only filesystem for Linux
3  *
4  * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
5  * Phillip Lougher <phillip@lougher.demon.co.uk>
6  *
7  * This program is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU General Public License
9  * as published by the Free Software Foundation; either version 2,
10  * or (at your option) any later version.
11  *
12  * This program is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  * GNU General Public License for more details.
16  *
17  * You should have received a copy of the GNU General Public License
18  * along with this program; if not, write to the Free Software
19  * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
20  *
21  * zlib_wrapper.c
22  */
23
24
25 #include <linux/mutex.h>
26 #include <linux/buffer_head.h>
27 #include <linux/slab.h>
28 #include <linux/zlib.h>
29
30 #include "squashfs_fs.h"
31 #include "squashfs_fs_sb.h"
32 #include "squashfs.h"
33 #include "decompressor.h"
34
35 static void *zlib_init(struct squashfs_sb_info *dummy)
36 {
37         z_stream *stream = kmalloc(sizeof(z_stream), GFP_KERNEL);
38         if (stream == NULL)
39                 goto failed;
40         stream->workspace = kmalloc(zlib_inflate_workspacesize(),
41                 GFP_KERNEL);
42         if (stream->workspace == NULL)
43                 goto failed;
44
45         return stream;
46
47 failed:
48         ERROR("Failed to allocate zlib workspace\n");
49         kfree(stream);
50         return NULL;
51 }
52
53
54 static void zlib_free(void *strm)
55 {
56         z_stream *stream = strm;
57
58         if (stream)
59                 kfree(stream->workspace);
60         kfree(stream);
61 }
62
63
64 static int zlib_uncompress(struct squashfs_sb_info *msblk, void **buffer,
65         struct buffer_head **bh, int b, int offset, int length, int srclength,
66         int pages)
67 {
68         int zlib_err, zlib_init = 0;
69         int k = 0, page = 0;
70         z_stream *stream = msblk->stream;
71
72         mutex_lock(&msblk->read_data_mutex);
73
74         stream->avail_out = 0;
75         stream->avail_in = 0;
76
77         do {
78                 if (stream->avail_in == 0 && k < b) {
79                         int avail = min(length, msblk->devblksize - offset);
80                         length -= avail;
81                         wait_on_buffer(bh[k]);
82                         if (!buffer_uptodate(bh[k]))
83                                 goto release_mutex;
84
85                         stream->next_in = bh[k]->b_data + offset;
86                         stream->avail_in = avail;
87                         offset = 0;
88                 }
89
90                 if (stream->avail_out == 0 && page < pages) {
91                         stream->next_out = buffer[page++];
92                         stream->avail_out = PAGE_CACHE_SIZE;
93                 }
94
95                 if (!zlib_init) {
96                         zlib_err = zlib_inflateInit(stream);
97                         if (zlib_err != Z_OK) {
98                                 ERROR("zlib_inflateInit returned unexpected "
99                                         "result 0x%x, srclength %d\n",
100                                         zlib_err, srclength);
101                                 goto release_mutex;
102                         }
103                         zlib_init = 1;
104                 }
105
106                 zlib_err = zlib_inflate(stream, Z_SYNC_FLUSH);
107
108                 if (stream->avail_in == 0 && k < b)
109                         put_bh(bh[k++]);
110         } while (zlib_err == Z_OK);
111
112         if (zlib_err != Z_STREAM_END) {
113                 ERROR("zlib_inflate error, data probably corrupt\n");
114                 goto release_mutex;
115         }
116
117         zlib_err = zlib_inflateEnd(stream);
118         if (zlib_err != Z_OK) {
119                 ERROR("zlib_inflate error, data probably corrupt\n");
120                 goto release_mutex;
121         }
122
123         if (k < b) {
124                 ERROR("zlib_uncompress error, data remaining\n");
125                 goto release_mutex;
126         }
127
128         length = stream->total_out;
129         mutex_unlock(&msblk->read_data_mutex);
130         return length;
131
132 release_mutex:
133         mutex_unlock(&msblk->read_data_mutex);
134
135         for (; k < b; k++)
136                 put_bh(bh[k]);
137
138         return -EIO;
139 }
140
141 const struct squashfs_decompressor squashfs_zlib_comp_ops = {
142         .init = zlib_init,
143         .free = zlib_free,
144         .decompress = zlib_uncompress,
145         .id = ZLIB_COMPRESSION,
146         .name = "zlib",
147         .supported = 1
148 };
149