1 /*
2 * Copyright (C) 2012 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 #define LOG_TAG "cutils"
18
19 #include <cutils/fs.h>
20 #include <cutils/log.h>
21
22 #include <sys/types.h>
23 #include <sys/stat.h>
24 #include <fcntl.h>
25 #include <unistd.h>
26 #include <errno.h>
27 #include <string.h>
28 #include <limits.h>
29
30 #define ALL_PERMS (S_ISUID | S_ISGID | S_ISVTX | S_IRWXU | S_IRWXG | S_IRWXO)
31 #define BUF_SIZE 64
32
fs_prepare_dir(const char * path,mode_t mode,uid_t uid,gid_t gid)33 int fs_prepare_dir(const char* path, mode_t mode, uid_t uid, gid_t gid) {
34 // Check if path needs to be created
35 struct stat sb;
36 if (TEMP_FAILURE_RETRY(lstat(path, &sb)) == -1) {
37 if (errno == ENOENT) {
38 goto create;
39 } else {
40 ALOGE("Failed to lstat(%s): %s", path, strerror(errno));
41 return -1;
42 }
43 }
44
45 // Exists, verify status
46 if (!S_ISDIR(sb.st_mode)) {
47 ALOGE("Not a directory: %s", path);
48 return -1;
49 }
50 if (((sb.st_mode & ALL_PERMS) == mode) && (sb.st_uid == uid) && (sb.st_gid == gid)) {
51 return 0;
52 } else {
53 goto fixup;
54 }
55
56 create:
57 if (TEMP_FAILURE_RETRY(mkdir(path, mode)) == -1) {
58 if (errno != EEXIST) {
59 ALOGE("Failed to mkdir(%s): %s", path, strerror(errno));
60 return -1;
61 }
62 }
63
64 fixup:
65 if (TEMP_FAILURE_RETRY(chmod(path, mode)) == -1) {
66 ALOGE("Failed to chmod(%s, %d): %s", path, mode, strerror(errno));
67 return -1;
68 }
69 if (TEMP_FAILURE_RETRY(chown(path, uid, gid)) == -1) {
70 ALOGE("Failed to chown(%s, %d, %d): %s", path, uid, gid, strerror(errno));
71 return -1;
72 }
73
74 return 0;
75 }
76
fs_read_atomic_int(const char * path,int * out_value)77 int fs_read_atomic_int(const char* path, int* out_value) {
78 int fd = TEMP_FAILURE_RETRY(open(path, O_RDONLY));
79 if (fd == -1) {
80 ALOGE("Failed to read %s: %s", path, strerror(errno));
81 return -1;
82 }
83
84 char buf[BUF_SIZE];
85 if (TEMP_FAILURE_RETRY(read(fd, buf, BUF_SIZE)) == -1) {
86 ALOGE("Failed to read %s: %s", path, strerror(errno));
87 goto fail;
88 }
89 if (sscanf(buf, "%d", out_value) != 1) {
90 ALOGE("Failed to parse %s: %s", path, strerror(errno));
91 goto fail;
92 }
93 close(fd);
94 return 0;
95
96 fail:
97 close(fd);
98 *out_value = -1;
99 return -1;
100 }
101
fs_write_atomic_int(const char * path,int value)102 int fs_write_atomic_int(const char* path, int value) {
103 char temp[PATH_MAX];
104 if (snprintf(temp, PATH_MAX, "%s.XXXXXX", path) >= PATH_MAX) {
105 ALOGE("Path too long");
106 return -1;
107 }
108
109 int fd = TEMP_FAILURE_RETRY(mkstemp(temp));
110 if (fd == -1) {
111 ALOGE("Failed to open %s: %s", temp, strerror(errno));
112 return -1;
113 }
114
115 char buf[BUF_SIZE];
116 int len = snprintf(buf, BUF_SIZE, "%d", value) + 1;
117 if (len > BUF_SIZE) {
118 ALOGE("Value %d too large: %s", value, strerror(errno));
119 goto fail;
120 }
121 if (TEMP_FAILURE_RETRY(write(fd, buf, len)) < len) {
122 ALOGE("Failed to write %s: %s", temp, strerror(errno));
123 goto fail;
124 }
125 if (close(fd) == -1) {
126 ALOGE("Failed to close %s: %s", temp, strerror(errno));
127 goto fail_closed;
128 }
129
130 if (rename(temp, path) == -1) {
131 ALOGE("Failed to rename %s to %s: %s", temp, path, strerror(errno));
132 goto fail_closed;
133 }
134
135 return 0;
136
137 fail:
138 close(fd);
139 fail_closed:
140 unlink(temp);
141 return -1;
142 }
143