Fat.cpp revision 97ac40e4e6f3ed0bd5d6878d7d8d4a54fcaecb76
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 <fcntl.h>
19#include <unistd.h>
20#include <errno.h>
21#include <string.h>
22#include <dirent.h>
23#include <errno.h>
24#include <fcntl.h>
25
26#include <sys/types.h>
27#include <sys/stat.h>
28#include <sys/types.h>
29#include <sys/mman.h>
30#include <sys/mount.h>
31
32#include <linux/kdev_t.h>
33
34#define LOG_TAG "Vold"
35
36#include <cutils/log.h>
37#include <cutils/properties.h>
38
39#include "Fat.h"
40
41static char FSCK_MSDOS_PATH[] = "/system/bin/fsck_msdos";
42static char MKDOSFS_PATH[] = "/system/bin/newfs_msdos";
43extern "C" int logwrap(int argc, const char **argv, int background);
44extern "C" int mount(const char *, const char *, const char *, unsigned long, const void *);
45
46int Fat::check(const char *fsPath) {
47    bool rw = true;
48    if (access(FSCK_MSDOS_PATH, X_OK)) {
49        SLOGW("Skipping fs checks\n");
50        return 0;
51    }
52
53    int pass = 1;
54    int rc = 0;
55    do {
56        const char *args[5];
57        args[0] = FSCK_MSDOS_PATH;
58        args[1] = "-p";
59        args[2] = "-f";
60        args[3] = fsPath;
61        args[4] = NULL;
62
63        rc = logwrap(4, args, 1);
64
65        switch(rc) {
66        case 0:
67            SLOGI("Filesystem check completed OK");
68            return 0;
69
70        case 2:
71            SLOGE("Filesystem check failed (not a FAT filesystem)");
72            errno = ENODATA;
73            return -1;
74
75        case 4:
76            if (pass++ <= 3) {
77                SLOGW("Filesystem modified - rechecking (pass %d)",
78                        pass);
79                continue;
80            }
81            SLOGE("Failing check after too many rechecks");
82            errno = EIO;
83            return -1;
84
85        default:
86            SLOGE("Filesystem check failed (unknown exit code %d)", rc);
87            errno = EIO;
88            return -1;
89        }
90    } while (0);
91
92    return 0;
93}
94
95int Fat::doMount(const char *fsPath, const char *mountPoint,
96                 bool ro, bool remount, int ownerUid, int ownerGid,
97                 int permMask, bool createLost) {
98    int rc;
99    unsigned long flags;
100    char mountData[255];
101
102    flags = MS_NODEV | MS_NOEXEC | MS_NOSUID | MS_DIRSYNC;
103
104    flags |= (ro ? MS_RDONLY : 0);
105    flags |= (remount ? MS_REMOUNT : 0);
106
107    /*
108     * Note: This is a temporary hack. If the sampling profiler is enabled,
109     * we make the SD card world-writable so any process can write snapshots.
110     *
111     * TODO: Remove this code once we have a drop box in system_server.
112     */
113    char value[PROPERTY_VALUE_MAX];
114    property_get("persist.sampling_profiler", value, "");
115    if (value[0] == '1') {
116        SLOGW("The SD card is world-writable because the"
117            " 'persist.sampling_profiler' system property is set to '1'.");
118        permMask = 0;
119    }
120
121    sprintf(mountData,
122            "utf8,uid=%d,gid=%d,fmask=%o,dmask=%o,shortname=mixed",
123            ownerUid, ownerGid, permMask, permMask);
124
125    rc = mount(fsPath, mountPoint, "vfat", flags, mountData);
126
127    if (rc && errno == EROFS) {
128        SLOGE("%s appears to be a read only filesystem - retrying mount RO", fsPath);
129        flags |= MS_RDONLY;
130        rc = mount(fsPath, mountPoint, "vfat", flags, mountData);
131    }
132
133    if (rc == 0 && createLost) {
134        char *lost_path;
135        asprintf(&lost_path, "%s/LOST.DIR", mountPoint);
136        if (access(lost_path, F_OK)) {
137            /*
138             * Create a LOST.DIR in the root so we have somewhere to put
139             * lost cluster chains (fsck_msdos doesn't currently do this)
140             */
141            if (mkdir(lost_path, 0755)) {
142                SLOGE("Unable to create LOST.DIR (%s)", strerror(errno));
143            }
144        }
145        free(lost_path);
146    }
147
148    return rc;
149}
150
151int Fat::format(const char *fsPath, unsigned int numSectors) {
152    int fd;
153    const char *args[11];
154    int rc;
155
156    args[0] = MKDOSFS_PATH;
157    args[1] = "-F";
158    args[2] = "32";
159    args[3] = "-O";
160    args[4] = "android";
161    args[5] = "-c";
162    args[6] = "8";
163
164    if (numSectors) {
165        char tmp[32];
166        snprintf(tmp, sizeof(tmp), "%u", numSectors);
167        const char *size = tmp;
168        args[7] = "-s";
169        args[8] = size;
170        args[9] = fsPath;
171        args[10] = NULL;
172        rc = logwrap(11, args, 1);
173    } else {
174        args[7] = fsPath;
175        args[8] = NULL;
176        rc = logwrap(9, args, 1);
177    }
178
179    if (rc == 0) {
180        SLOGI("Filesystem formatted OK");
181        return 0;
182    } else {
183        SLOGE("Format failed (unknown exit code %d)", rc);
184        errno = EIO;
185        return -1;
186    }
187    return 0;
188}
189