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 <errno.h>
18 #include <fcntl.h>
19 #include <stdio.h>
20 #include <stdlib.h>
21 #include <string.h>
22 #include <sys/mount.h>
23 #include <unistd.h>
24
25 #include "sysdeps.h"
26
27 #define TRACE_TAG TRACE_ADB
28 #include "adb.h"
29
30
31 static int system_ro = 1;
32 static int vendor_ro = 1;
33
34 /* Returns the device used to mount a directory in /proc/mounts */
find_mount(const char * dir)35 static char *find_mount(const char *dir)
36 {
37 int fd;
38 int res;
39 char *token = NULL;
40 const char delims[] = "\n";
41 char buf[4096];
42
43 fd = unix_open("/proc/mounts", O_RDONLY | O_CLOEXEC);
44 if (fd < 0)
45 return NULL;
46
47 buf[sizeof(buf) - 1] = '\0';
48 adb_read(fd, buf, sizeof(buf) - 1);
49 adb_close(fd);
50
51 token = strtok(buf, delims);
52
53 while (token) {
54 char mount_dev[256];
55 char mount_dir[256];
56 int mount_freq;
57 int mount_passno;
58
59 res = sscanf(token, "%255s %255s %*s %*s %d %d\n",
60 mount_dev, mount_dir, &mount_freq, &mount_passno);
61 mount_dev[255] = 0;
62 mount_dir[255] = 0;
63 if (res == 4 && (strcmp(dir, mount_dir) == 0))
64 return strdup(mount_dev);
65
66 token = strtok(NULL, delims);
67 }
68 return NULL;
69 }
70
hasVendorPartition()71 static int hasVendorPartition()
72 {
73 struct stat info;
74 if (!lstat("/vendor", &info))
75 if ((info.st_mode & S_IFMT) == S_IFDIR)
76 return true;
77 return false;
78 }
79
80 /* Init mounts /system as read only, remount to enable writes. */
remount(const char * dir,int * dir_ro)81 static int remount(const char* dir, int* dir_ro)
82 {
83 char *dev;
84 int fd;
85 int OFF = 0;
86
87 if (dir_ro == 0) {
88 return 0;
89 }
90
91 dev = find_mount(dir);
92
93 if (!dev)
94 return -1;
95
96 fd = unix_open(dev, O_RDONLY | O_CLOEXEC);
97 if (fd < 0)
98 return -1;
99
100 ioctl(fd, BLKROSET, &OFF);
101 adb_close(fd);
102
103 *dir_ro = mount(dev, dir, "none", MS_REMOUNT, NULL);
104
105 free(dev);
106
107 return *dir_ro;
108 }
109
write_string(int fd,const char * str)110 static void write_string(int fd, const char* str)
111 {
112 writex(fd, str, strlen(str));
113 }
114
remount_service(int fd,void * cookie)115 void remount_service(int fd, void *cookie)
116 {
117 char buffer[200];
118 if (remount("/system", &system_ro)) {
119 snprintf(buffer, sizeof(buffer), "remount of system failed: %s\n",strerror(errno));
120 write_string(fd, buffer);
121 }
122
123 if (hasVendorPartition()) {
124 if (remount("/vendor", &vendor_ro)) {
125 snprintf(buffer, sizeof(buffer), "remount of vendor failed: %s\n",strerror(errno));
126 write_string(fd, buffer);
127 }
128 }
129
130 if (!system_ro && (!vendor_ro || !hasVendorPartition()))
131 write_string(fd, "remount succeeded\n");
132 else {
133 write_string(fd, "remount failed\n");
134 }
135
136 adb_close(fd);
137 }
138
139