Vfat.cpp revision a4f48d0f44d09b6a9a3b16f6c0121ffd5123eef3 
1/*
2 * Copyright (C) 2008 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include <stdio.h>
18#include <stdlib.h>
19#include <fcntl.h>
20#include <unistd.h>
21#include <errno.h>
22#include <string.h>
23#include <dirent.h>
24#include <errno.h>
25#include <fcntl.h>
26
27#include <sys/types.h>
28#include <sys/stat.h>
29#include <sys/types.h>
30#include <sys/mman.h>
31#include <sys/mount.h>
32#include <sys/wait.h>
33#include <linux/fs.h>
34#include <sys/ioctl.h>
35
36#include <linux/kdev_t.h>
37
38#define LOG_TAG "Vold"
39
40#include <base/logging.h>
41#include <base/stringprintf.h>
42#include <cutils/log.h>
43#include <cutils/properties.h>
44#include <selinux/selinux.h>
45
46#include <logwrap/logwrap.h>
47
48#include "Vfat.h"
49#include "Utils.h"
50#include "VoldUtil.h"
51
52using android::base::StringPrintf;
53
54namespace android {
55namespace vold {
56namespace vfat {
57
58static const char* kMkfsPath = "/system/bin/newfs_msdos";
59static const char* kFsckPath = "/system/bin/fsck_msdos";
60
61bool IsSupported() {
62    return access(kMkfsPath, X_OK) == 0
63            && access(kFsckPath, X_OK) == 0
64            && IsFilesystemSupported("vfat");
65}
66
67status_t Check(const std::string& source) {
68    if (access(kFsckPath, X_OK)) {
69        SLOGW("Skipping fs checks\n");
70        return 0;
71    }
72
73    int pass = 1;
74    int rc = 0;
75    do {
76        std::vector<std::string> cmd;
77        cmd.push_back(kFsckPath);
78        cmd.push_back("-p");
79        cmd.push_back("-f");
80        cmd.push_back(source);
81
82        // Fat devices are currently always untrusted
83        rc = ForkExecvp(cmd, sFsckUntrustedContext);
84
85        if (rc < 0) {
86            SLOGE("Filesystem check failed due to logwrap error");
87            errno = EIO;
88            return -1;
89        }
90
91        switch(rc) {
92        case 0:
93            SLOGI("Filesystem check completed OK");
94            return 0;
95
96        case 2:
97            SLOGE("Filesystem check failed (not a FAT filesystem)");
98            errno = ENODATA;
99            return -1;
100
101        case 4:
102            if (pass++ <= 3) {
103                SLOGW("Filesystem modified - rechecking (pass %d)",
104                        pass);
105                continue;
106            }
107            SLOGE("Failing check after too many rechecks");
108            errno = EIO;
109            return -1;
110
111        default:
112            SLOGE("Filesystem check failed (unknown exit code %d)", rc);
113            errno = EIO;
114            return -1;
115        }
116    } while (0);
117
118    return 0;
119}
120
121status_t Mount(const std::string& source, const std::string& target, bool ro,
122        bool remount, bool executable, int ownerUid, int ownerGid, int permMask,
123        bool createLost) {
124    int rc;
125    unsigned long flags;
126    char mountData[255];
127
128    const char* c_source = source.c_str();
129    const char* c_target = target.c_str();
130
131    flags = MS_NODEV | MS_NOSUID | MS_DIRSYNC;
132
133    flags |= (executable ? 0 : MS_NOEXEC);
134    flags |= (ro ? MS_RDONLY : 0);
135    flags |= (remount ? MS_REMOUNT : 0);
136
137    sprintf(mountData,
138            "utf8,uid=%d,gid=%d,fmask=%o,dmask=%o,shortname=mixed",
139            ownerUid, ownerGid, permMask, permMask);
140
141    rc = mount(c_source, c_target, "vfat", flags, mountData);
142
143    if (rc && errno == EROFS) {
144        SLOGE("%s appears to be a read only filesystem - retrying mount RO", c_source);
145        flags |= MS_RDONLY;
146        rc = mount(c_source, c_target, "vfat", flags, mountData);
147    }
148
149    if (rc == 0 && createLost) {
150        char *lost_path;
151        asprintf(&lost_path, "%s/LOST.DIR", c_target);
152        if (access(lost_path, F_OK)) {
153            /*
154             * Create a LOST.DIR in the root so we have somewhere to put
155             * lost cluster chains (fsck_msdos doesn't currently do this)
156             */
157            if (mkdir(lost_path, 0755)) {
158                SLOGE("Unable to create LOST.DIR (%s)", strerror(errno));
159            }
160        }
161        free(lost_path);
162    }
163
164    return rc;
165}
166
167status_t Format(const std::string& source, unsigned long numSectors) {
168    std::vector<std::string> cmd;
169    cmd.push_back(kMkfsPath);
170    cmd.push_back("-F");
171    cmd.push_back("32");
172    cmd.push_back("-O");
173    cmd.push_back("android");
174    cmd.push_back("-c");
175    cmd.push_back("64");
176    cmd.push_back("-A");
177
178    if (numSectors) {
179        cmd.push_back("-s");
180        cmd.push_back(StringPrintf("%lu", numSectors));
181    }
182
183    cmd.push_back(source);
184
185    int rc = ForkExecvp(cmd);
186    if (rc < 0) {
187        SLOGE("Filesystem format failed due to logwrap error");
188        errno = EIO;
189        return -1;
190    }
191
192    if (rc == 0) {
193        SLOGI("Filesystem formatted OK");
194        return 0;
195    } else {
196        SLOGE("Format failed (unknown exit code %d)", rc);
197        errno = EIO;
198        return -1;
199    }
200    return 0;
201}
202
203}  // namespace vfat
204}  // namespace vold
205}  // namespace android
206