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
tzset_unlocked()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__)
make_path(const char * path_prefix_variable,const char * path_suffix)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
__bionic_open_tzdata_path(const char * path,const char * olson_id,int32_t * entry_length)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
__bionic_open_tzdata(const char * olson_id,int32_t * entry_length)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