1 /*
2  * Copyright (C) 2007 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 "mounts.h"
18 
19 #include <errno.h>
20 #include <fcntl.h>
21 #include <mntent.h>
22 #include <stdio.h>
23 #include <stdlib.h>
24 #include <string.h>
25 #include <sys/mount.h>
26 
27 #include <string>
28 #include <vector>
29 
30 struct MountedVolume {
31     std::string device;
32     std::string mount_point;
33     std::string filesystem;
34     std::string flags;
35 };
36 
37 std::vector<MountedVolume*> g_mounts_state;
38 
scan_mounted_volumes()39 bool scan_mounted_volumes() {
40     for (size_t i = 0; i < g_mounts_state.size(); ++i) {
41         delete g_mounts_state[i];
42     }
43     g_mounts_state.clear();
44 
45     // Open and read mount table entries.
46     FILE* fp = setmntent("/proc/mounts", "re");
47     if (fp == NULL) {
48         return false;
49     }
50     mntent* e;
51     while ((e = getmntent(fp)) != NULL) {
52         MountedVolume* v = new MountedVolume;
53         v->device = e->mnt_fsname;
54         v->mount_point = e->mnt_dir;
55         v->filesystem = e->mnt_type;
56         v->flags = e->mnt_opts;
57         g_mounts_state.push_back(v);
58     }
59     endmntent(fp);
60     return true;
61 }
62 
find_mounted_volume_by_device(const char * device)63 MountedVolume* find_mounted_volume_by_device(const char* device) {
64     for (size_t i = 0; i < g_mounts_state.size(); ++i) {
65         if (g_mounts_state[i]->device == device) return g_mounts_state[i];
66     }
67     return nullptr;
68 }
69 
find_mounted_volume_by_mount_point(const char * mount_point)70 MountedVolume* find_mounted_volume_by_mount_point(const char* mount_point) {
71     for (size_t i = 0; i < g_mounts_state.size(); ++i) {
72         if (g_mounts_state[i]->mount_point == mount_point) return g_mounts_state[i];
73     }
74     return nullptr;
75 }
76 
unmount_mounted_volume(MountedVolume * volume)77 int unmount_mounted_volume(MountedVolume* volume) {
78     // Intentionally pass the empty string to umount if the caller tries
79     // to unmount a volume they already unmounted using this
80     // function.
81     std::string mount_point = volume->mount_point;
82     volume->mount_point.clear();
83     return umount(mount_point.c_str());
84 }
85 
remount_read_only(MountedVolume * volume)86 int remount_read_only(MountedVolume* volume) {
87     return mount(volume->device.c_str(), volume->mount_point.c_str(), volume->filesystem.c_str(),
88                  MS_NOATIME | MS_NODEV | MS_NODIRATIME | MS_RDONLY | MS_REMOUNT, 0);
89 }
90