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the License. 15 */ 16 17 #define LOG_TAG "cutils" 18 19 /* These defines are only needed because prebuilt headers are out of date */ 20 #define __USE_XOPEN2K8 1 21 #define _ATFILE_SOURCE 1 22 #define _GNU_SOURCE 1 23 24 #include <cutils/fs.h> 25 #include <cutils/log.h> 26 27 #include <sys/types.h> 28 #include <sys/stat.h> 29 #include <fcntl.h> 30 #include <unistd.h> 31 #include <errno.h> 32 #include <string.h> 33 #include <limits.h> 34 #include <stdlib.h> 35 #include <dirent.h> 36 37 #define ALL_PERMS (S_ISUID | S_ISGID | S_ISVTX | S_IRWXU | S_IRWXG | S_IRWXO) 38 #define BUF_SIZE 64 39 40 int fs_prepare_dir(const char* path, mode_t mode, uid_t uid, gid_t gid) { 41 // Check if path needs to be created 42 struct stat sb; 43 if (TEMP_FAILURE_RETRY(lstat(path, &sb)) == -1) { 44 if (errno == ENOENT) { 45 goto create; 46 } else { 47 ALOGE("Failed to lstat(%s): %s", path, strerror(errno)); 48 return -1; 49 } 50 } 51 52 // Exists, verify status 53 if (!S_ISDIR(sb.st_mode)) { 54 ALOGE("Not a directory: %s", path); 55 return -1; 56 } 57 if (((sb.st_mode & ALL_PERMS) == mode) && (sb.st_uid == uid) && (sb.st_gid == gid)) { 58 return 0; 59 } else { 60 goto fixup; 61 } 62 63 create: 64 if (TEMP_FAILURE_RETRY(mkdir(path, mode)) == -1) { 65 if (errno != EEXIST) { 66 ALOGE("Failed to mkdir(%s): %s", path, strerror(errno)); 67 return -1; 68 } 69 } 70 71 fixup: 72 if (TEMP_FAILURE_RETRY(chmod(path, mode)) == -1) { 73 ALOGE("Failed to chmod(%s, %d): %s", path, mode, strerror(errno)); 74 return -1; 75 } 76 if (TEMP_FAILURE_RETRY(chown(path, uid, gid)) == -1) { 77 ALOGE("Failed to chown(%s, %d, %d): %s", path, uid, gid, strerror(errno)); 78 return -1; 79 } 80 81 return 0; 82 } 83 84 int fs_read_atomic_int(const char* path, int* out_value) { 85 int fd = TEMP_FAILURE_RETRY(open(path, O_RDONLY)); 86 if (fd == -1) { 87 ALOGE("Failed to read %s: %s", path, strerror(errno)); 88 return -1; 89 } 90 91 char buf[BUF_SIZE]; 92 if (TEMP_FAILURE_RETRY(read(fd, buf, BUF_SIZE)) == -1) { 93 ALOGE("Failed to read %s: %s", path, strerror(errno)); 94 goto fail; 95 } 96 if (sscanf(buf, "%d", out_value) != 1) { 97 ALOGE("Failed to parse %s: %s", path, strerror(errno)); 98 goto fail; 99 } 100 close(fd); 101 return 0; 102 103 fail: 104 close(fd); 105 *out_value = -1; 106 return -1; 107 } 108 109 int fs_write_atomic_int(const char* path, int value) { 110 char temp[PATH_MAX]; 111 if (snprintf(temp, PATH_MAX, "%s.XXXXXX", path) >= PATH_MAX) { 112 ALOGE("Path too long"); 113 return -1; 114 } 115 116 int fd = TEMP_FAILURE_RETRY(mkstemp(temp)); 117 if (fd == -1) { 118 ALOGE("Failed to open %s: %s", temp, strerror(errno)); 119 return -1; 120 } 121 122 char buf[BUF_SIZE]; 123 int len = snprintf(buf, BUF_SIZE, "%d", value) + 1; 124 if (len > BUF_SIZE) { 125 ALOGE("Value %d too large: %s", value, strerror(errno)); 126 goto fail; 127 } 128 if (TEMP_FAILURE_RETRY(write(fd, buf, len)) < len) { 129 ALOGE("Failed to write %s: %s", temp, strerror(errno)); 130 goto fail; 131 } 132 if (close(fd) == -1) { 133 ALOGE("Failed to close %s: %s", temp, strerror(errno)); 134 goto fail_closed; 135 } 136 137 if (rename(temp, path) == -1) { 138 ALOGE("Failed to rename %s to %s: %s", temp, path, strerror(errno)); 139 goto fail_closed; 140 } 141 142 return 0; 143 144 fail: 145 close(fd); 146 fail_closed: 147 unlink(temp); 148 return -1; 149 } 150 151 #ifndef __APPLE__ 152 153 int fs_mkdirs(const char* path, mode_t mode) { 154 int res = 0; 155 int fd = 0; 156 struct stat sb; 157 char* buf = strdup(path); 158 159 if (*buf != '/') { 160 ALOGE("Relative paths are not allowed: %s", buf); 161 res = -EINVAL; 162 goto done; 163 } 164 165 if ((fd = open("/", 0)) == -1) { 166 ALOGE("Failed to open(/): %s", strerror(errno)); 167 res = -errno; 168 goto done; 169 } 170 171 char* segment = buf + 1; 172 char* p = segment; 173 while (*p != '\0') { 174 if (*p == '/') { 175 *p = '\0'; 176 177 if (!strcmp(segment, "..") || !strcmp(segment, ".") || !strcmp(segment, "")) { 178 ALOGE("Invalid path: %s", buf); 179 res = -EINVAL; 180 goto done_close; 181 } 182 183 if (fstatat(fd, segment, &sb, AT_SYMLINK_NOFOLLOW) != 0) { 184 if (errno == ENOENT) { 185 /* Nothing there yet; let's create it! */ 186 if (mkdirat(fd, segment, mode) != 0) { 187 if (errno == EEXIST) { 188 /* We raced with someone; ignore */ 189 } else { 190 ALOGE("Failed to mkdirat(%s): %s", buf, strerror(errno)); 191 res = -errno; 192 goto done_close; 193 } 194 } 195 } else { 196 ALOGE("Failed to fstatat(%s): %s", buf, strerror(errno)); 197 res = -errno; 198 goto done_close; 199 } 200 } else { 201 if (S_ISLNK(sb.st_mode)) { 202 ALOGE("Symbolic links are not allowed: %s", buf); 203 res = -ELOOP; 204 goto done_close; 205 } 206 if (!S_ISDIR(sb.st_mode)) { 207 ALOGE("Existing segment not a directory: %s", buf); 208 res = -ENOTDIR; 209 goto done_close; 210 } 211 } 212 213 /* Yay, segment is ready for us to step into */ 214 int next_fd; 215 if ((next_fd = openat(fd, segment, O_NOFOLLOW | O_CLOEXEC)) == -1) { 216 ALOGE("Failed to openat(%s): %s", buf, strerror(errno)); 217 res = -errno; 218 goto done_close; 219 } 220 221 close(fd); 222 fd = next_fd; 223 224 *p = '/'; 225 segment = p + 1; 226 } 227 p++; 228 } 229 230 done_close: 231 close(fd); 232 done: 233 free(buf); 234 return res; 235 } 236 237 #endif 238
