1 /* 2 * Copyright (C) 2017 The Android Open Source Project 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in 12 * the documentation and/or other materials provided with the 13 * distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <arpa/inet.h> // For ntohl(3). 30 #include <errno.h> 31 #include <fcntl.h> 32 #include <stdint.h> 33 #include <stdlib.h> 34 #include <unistd.h> 35 36 #include "private/CachedProperty.h" 37 38 extern "C" void tzset_unlocked(void); 39 extern "C" int __bionic_open_tzdata(const char*, int32_t*); 40 41 extern "C" void tzsetlcl(char const*); 42 43 void tzset_unlocked() { 44 // The TZ environment variable is meant to override the system-wide setting. 45 const char* name = getenv("TZ"); 46 char buf[PROP_VALUE_MAX]; 47 48 // If that's not set, look at the "persist.sys.timezone" system property. 49 if (name == nullptr) { 50 static CachedProperty persist_sys_timezone("persist.sys.timezone"); 51 52 if ((name = persist_sys_timezone.Get()) != nullptr && strlen(name) > 3) { 53 // POSIX and Java disagree about the sign in a timezone string. For POSIX, "GMT+3" means 54 // "3 hours west/behind", but for Java it means "3 hours east/ahead". Since (a) Java is 55 // the one that matches human expectations and (b) this system property is used directly 56 // by Java, we flip the sign here to translate from Java to POSIX. http://b/25463955. 57 char sign = name[3]; 58 if (sign == '-' || sign == '+') { 59 strlcpy(buf, name, sizeof(buf)); 60 buf[3] = (sign == '-') ? '+' : '-'; 61 name = buf; 62 } 63 } 64 } 65 66 // If the system property is also not available (because you're running AOSP on a WiFi-only 67 // device, say), fall back to GMT. 68 if (name == nullptr) name = "GMT"; 69 70 tzsetlcl(name); 71 } 72 73 #if !defined(__ANDROID__) 74 static char* make_path(const char* path_prefix_variable, 75 const char* path_suffix) { 76 const char* path_prefix = getenv(path_prefix_variable); 77 if (path_prefix == nullptr) { 78 fprintf(stderr, "%s: %s not set!\n", __FUNCTION__, path_prefix_variable); 79 abort(); 80 } 81 char* path; 82 if (asprintf(&path, "%s/%s", path_prefix, path_suffix) == -1) { 83 fprintf(stderr, "%s: couldn't allocate \"%s/%s\"\n", __FUNCTION__, path_prefix, path_suffix); 84 abort(); 85 } 86 return path; 87 } 88 #endif 89 90 // byte[12] tzdata_version -- "tzdata2012f\0" 91 // int index_offset 92 // int data_offset 93 // int zonetab_offset 94 struct bionic_tzdata_header_t { 95 char tzdata_version[12]; 96 int32_t index_offset; 97 int32_t data_offset; 98 int32_t zonetab_offset; 99 }; 100 static constexpr size_t NAME_LENGTH = 40; 101 struct index_entry_t { 102 char buf[NAME_LENGTH]; 103 int32_t start; 104 int32_t length; 105 int32_t unused; // Was raw GMT offset; always 0 since tzdata2014f (L). 106 }; 107 108 static int __bionic_open_tzdata_path(const char* path, 109 const char* olson_id, 110 int32_t* entry_length) { 111 int fd = TEMP_FAILURE_RETRY(open(path, O_RDONLY | O_CLOEXEC)); 112 if (fd == -1) { 113 return -2; // Distinguish failure to find any data from failure to find a specific id. 114 } 115 116 bionic_tzdata_header_t header = {}; 117 ssize_t bytes_read = TEMP_FAILURE_RETRY(read(fd, &header, sizeof(header))); 118 if (bytes_read != sizeof(header)) { 119 fprintf(stderr, "%s: could not read header of \"%s\": %s\n", 120 __FUNCTION__, path, (bytes_read == -1) ? strerror(errno) : "short read"); 121 close(fd); 122 return -1; 123 } 124 125 if (strncmp(header.tzdata_version, "tzdata", 6) != 0 || header.tzdata_version[11] != 0) { 126 fprintf(stderr, "%s: bad magic in \"%s\": \"%.6s\"\n", __FUNCTION__, path, header.tzdata_version); 127 close(fd); 128 return -1; 129 } 130 131 if (TEMP_FAILURE_RETRY(lseek(fd, ntohl(header.index_offset), SEEK_SET)) == -1) { 132 fprintf(stderr, "%s: couldn't seek to index in \"%s\": %s\n", __FUNCTION__, path, strerror(errno)); 133 close(fd); 134 return -1; 135 } 136 137 if (ntohl(header.index_offset) > ntohl(header.data_offset)) { 138 fprintf(stderr, "%s: invalid data and index offsets in \"%s\": %u %u\n", 139 __FUNCTION__, path, ntohl(header.data_offset), ntohl(header.index_offset)); 140 close(fd); 141 return -1; 142 } 143 const size_t index_size = ntohl(header.data_offset) - ntohl(header.index_offset); 144 if ((index_size % sizeof(index_entry_t)) != 0) { 145 fprintf(stderr, "%s: invalid index size in \"%s\": %zd\n", __FUNCTION__, path, index_size); 146 close(fd); 147 return -1; 148 } 149 150 off_t specific_zone_offset = -1; 151 char* index = reinterpret_cast<char*>(malloc(index_size)); 152 if (index == nullptr) { 153 fprintf(stderr, "%s: couldn't allocate %zd-byte index for \"%s\"\n", __FUNCTION__, index_size, path); 154 close(fd); 155 return -1; 156 } 157 if (TEMP_FAILURE_RETRY(read(fd, index, index_size)) != static_cast<ssize_t>(index_size)) { 158 fprintf(stderr, "%s: could not read index of \"%s\": %s\n", 159 __FUNCTION__, path, (bytes_read == -1) ? strerror(errno) : "short read"); 160 free(index); 161 close(fd); 162 return -1; 163 } 164 165 size_t id_count = index_size / sizeof(index_entry_t); 166 index_entry_t* entry = reinterpret_cast<index_entry_t*>(index); 167 for (size_t i = 0; i < id_count; ++i) { 168 char this_id[NAME_LENGTH + 1]; 169 memcpy(this_id, entry->buf, NAME_LENGTH); 170 this_id[NAME_LENGTH] = '\0'; 171 172 if (strcmp(this_id, olson_id) == 0) { 173 specific_zone_offset = ntohl(entry->start) + ntohl(header.data_offset); 174 *entry_length = ntohl(entry->length); 175 break; 176 } 177 178 ++entry; 179 } 180 free(index); 181 182 if (specific_zone_offset == -1) { 183 close(fd); 184 return -1; 185 } 186 187 if (TEMP_FAILURE_RETRY(lseek(fd, specific_zone_offset, SEEK_SET)) == -1) { 188 fprintf(stderr, "%s: could not seek to %ld in \"%s\": %s\n", 189 __FUNCTION__, specific_zone_offset, path, strerror(errno)); 190 close(fd); 191 return -1; 192 } 193 194 // TODO: check that there's TZ_MAGIC at this offset, so we can fall back to the other file if not. 195 196 return fd; 197 } 198 199 int __bionic_open_tzdata(const char* olson_id, int32_t* entry_length) { 200 int fd; 201 202 #if defined(__ANDROID__) 203 // On Android devices, try the four hard-coded locations in order. 204 // 205 // 1: The O-MR1 time zone updates via APK update mechanism. This is 206 // tried first because it allows us to test that the time zone updates 207 // via APK mechanism still works even on devices with the time zone 208 // module. 209 fd = __bionic_open_tzdata_path("/data/misc/zoneinfo/current/tzdata", 210 olson_id, entry_length); 211 if (fd >= 0) return fd; 212 213 // 2: The time zone data module which may contain newer data on 214 // devices that support module updates. 215 fd = __bionic_open_tzdata_path("/apex/com.android.tzdata/etc/tz/tzdata", 216 olson_id, entry_length); 217 if (fd >= 0) return fd; 218 219 // 3: The runtime module, which should exist even on devices that 220 // do not support APEX file updates. 221 fd = __bionic_open_tzdata_path("/apex/com.android.runtime/etc/tz/tzdata", 222 olson_id, entry_length); 223 if (fd >= 0) return fd; 224 225 // 4: The ultimate fallback: the non-updatable copy in /system. 226 fd = __bionic_open_tzdata_path("/system/usr/share/zoneinfo/tzdata", 227 olson_id, entry_length); 228 if (fd >= 0) return fd; 229 #else 230 // On the host, we don't expect those locations to exist, and we're not 231 // worried about security so we trust $ANDROID_DATA, $ANDROID_RUNTIME_ROOT, 232 // $ANDROID_TZDATA_ROOT, and $ANDROID_ROOT to point us in the right direction. 233 char* path = make_path("ANDROID_DATA", "/misc/zoneinfo/current/tzdata"); 234 fd = __bionic_open_tzdata_path(path, olson_id, entry_length); 235 free(path); 236 if (fd >= 0) return fd; 237 238 path = make_path("ANDROID_TZDATA_ROOT", "/etc/tz/tzdata"); 239 fd = __bionic_open_tzdata_path(path, olson_id, entry_length); 240 free(path); 241 if (fd >= 0) return fd; 242 243 path = make_path("ANDROID_RUNTIME_ROOT", "/etc/tz/tzdata"); 244 fd = __bionic_open_tzdata_path(path, olson_id, entry_length); 245 free(path); 246 if (fd >= 0) return fd; 247 248 path = make_path("ANDROID_ROOT", "/usr/share/zoneinfo/tzdata"); 249 fd = __bionic_open_tzdata_path(path, olson_id, entry_length); 250 free(path); 251 if (fd >= 0) return fd; 252 #endif 253 254 // Not finding any tzdata is more serious that not finding a specific zone, 255 // and worth logging. 256 if (fd == -2) { 257 // The first thing that 'recovery' does is try to format the current time. It doesn't have 258 // any tzdata available, so we must not abort here --- doing so breaks the recovery image! 259 fprintf(stderr, "%s: couldn't find any tzdata when looking for %s!\n", __FUNCTION__, olson_id); 260 } 261 262 return fd; 263 } 264
