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 <stdlib.h>
18 #include <stdio.h>
19 #include <unistd.h>
20 #include <string.h>
21 #include <fcntl.h>
22 #include <sys/mount.h>
23 #include <errno.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
33 /* Returns the device used to mount a directory in /proc/mounts */
find_mount(const char * dir)34 static char *find_mount(const char *dir)
35 {
36 int fd;
37 int res;
38 int size;
39 char *token = NULL;
40 const char delims[] = "\n";
41 char buf[4096];
42
43 fd = unix_open("/proc/mounts", O_RDONLY);
44 if (fd < 0)
45 return NULL;
46
47 buf[sizeof(buf) - 1] = '\0';
48 size = 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
71 /* Init mounts /system as read only, remount to enable writes. */
remount_system()72 static int remount_system()
73 {
74 char *dev;
75 int fd;
76 int OFF = 0;
77
78 if (system_ro == 0) {
79 return 0;
80 }
81
82 dev = find_mount("/system");
83
84 if (!dev)
85 return -1;
86
87 fd = unix_open(dev, O_RDONLY);
88 if (fd < 0)
89 return -1;
90
91 ioctl(fd, BLKROSET, &OFF);
92 adb_close(fd);
93
94 system_ro = mount(dev, "/system", "none", MS_REMOUNT, NULL);
95
96 free(dev);
97
98 return system_ro;
99 }
100
write_string(int fd,const char * str)101 static void write_string(int fd, const char* str)
102 {
103 writex(fd, str, strlen(str));
104 }
105
remount_service(int fd,void * cookie)106 void remount_service(int fd, void *cookie)
107 {
108 int ret = remount_system();
109
110 if (!ret)
111 write_string(fd, "remount succeeded\n");
112 else {
113 char buffer[200];
114 snprintf(buffer, sizeof(buffer), "remount failed: %s\n", strerror(errno));
115 write_string(fd, buffer);
116 }
117
118 adb_close(fd);
119 }
120
121