squashfs: fix use of uninitialised variable in zlib & xz decompressors
[linux-3.10.git] / fs / squashfs / xz_wrapper.c
1 /*
2  * Squashfs - a compressed read only filesystem for Linux
3  *
4  * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
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  * xz_wrapper.c
22  */
23
24
25 #include <linux/mutex.h>
26 #include <linux/buffer_head.h>
27 #include <linux/slab.h>
28 #include <linux/xz.h>
29
30 #include "squashfs_fs.h"
31 #include "squashfs_fs_sb.h"
32 #include "squashfs_fs_i.h"
33 #include "squashfs.h"
34 #include "decompressor.h"
35
36 struct squashfs_xz {
37         struct xz_dec *state;
38         struct xz_buf buf;
39 };
40
41 static void *squashfs_xz_init(struct squashfs_sb_info *msblk)
42 {
43         int block_size = max_t(int, msblk->block_size, SQUASHFS_METADATA_SIZE);
44
45         struct squashfs_xz *stream = kmalloc(sizeof(*stream), GFP_KERNEL);
46         if (stream == NULL)
47                 goto failed;
48
49         stream->state = xz_dec_init(XZ_PREALLOC, block_size);
50         if (stream->state == NULL)
51                 goto failed;
52
53         return stream;
54
55 failed:
56         ERROR("Failed to allocate xz workspace\n");
57         kfree(stream);
58         return NULL;
59 }
60
61
62 static void squashfs_xz_free(void *strm)
63 {
64         struct squashfs_xz *stream = strm;
65
66         if (stream) {
67                 xz_dec_end(stream->state);
68                 kfree(stream);
69         }
70 }
71
72
73 static int squashfs_xz_uncompress(struct squashfs_sb_info *msblk, void **buffer,
74         struct buffer_head **bh, int b, int offset, int length, int srclength,
75         int pages)
76 {
77         enum xz_ret xz_err;
78         int avail, total = 0, k = 0, page = 0;
79         struct squashfs_xz *stream = msblk->stream;
80
81         mutex_lock(&msblk->read_data_mutex);
82
83         xz_dec_reset(stream->state);
84         stream->buf.in_pos = 0;
85         stream->buf.in_size = 0;
86         stream->buf.out_pos = 0;
87         stream->buf.out_size = PAGE_CACHE_SIZE;
88         stream->buf.out = buffer[page++];
89
90         do {
91                 if (stream->buf.in_pos == stream->buf.in_size && k < b) {
92                         avail = min(length, msblk->devblksize - offset);
93                         length -= avail;
94                         wait_on_buffer(bh[k]);
95                         if (!buffer_uptodate(bh[k]))
96                                 goto release_mutex;
97
98                         stream->buf.in = bh[k]->b_data + offset;
99                         stream->buf.in_size = avail;
100                         stream->buf.in_pos = 0;
101                         offset = 0;
102                 }
103
104                 if (stream->buf.out_pos == stream->buf.out_size
105                                                         && page < pages) {
106                         stream->buf.out = buffer[page++];
107                         stream->buf.out_pos = 0;
108                         total += PAGE_CACHE_SIZE;
109                 }
110
111                 xz_err = xz_dec_run(stream->state, &stream->buf);
112
113                 if (stream->buf.in_pos == stream->buf.in_size && k < b)
114                         put_bh(bh[k++]);
115         } while (xz_err == XZ_OK);
116
117         if (xz_err != XZ_STREAM_END) {
118                 ERROR("xz_dec_run error, data probably corrupt\n");
119                 goto release_mutex;
120         }
121
122         if (k < b) {
123                 ERROR("xz_uncompress error, input remaining\n");
124                 goto release_mutex;
125         }
126
127         total += stream->buf.out_pos;
128         mutex_unlock(&msblk->read_data_mutex);
129         return total;
130
131 release_mutex:
132         mutex_unlock(&msblk->read_data_mutex);
133
134         for (; k < b; k++)
135                 put_bh(bh[k]);
136
137         return -EIO;
138 }
139
140 const struct squashfs_decompressor squashfs_xz_comp_ops = {
141         .init = squashfs_xz_init,
142         .free = squashfs_xz_free,
143         .decompress = squashfs_xz_uncompress,
144         .id = XZ_COMPRESSION,
145         .name = "xz",
146         .supported = 1
147 };