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 <fcntl.h>
31 #include <stdint.h>
32 #include <stdlib.h>
33 #include <unistd.h>
34
35 #include "private/CachedProperty.h"
36
37 extern "C" void tzset_unlocked(void);
38 extern "C" int __bionic_open_tzdata(const char*, int32_t*);
39
40 extern "C" void tzsetlcl(char const*);
41
tzset_unlocked()42 void tzset_unlocked() {
43 // The TZ environment variable is meant to override the system-wide setting.
44 const char* name = getenv("TZ");
45 char buf[PROP_VALUE_MAX];
46
47 // If that's not set, look at the "persist.sys.timezone" system property.
48 if (name == nullptr) {
49 static CachedProperty persist_sys_timezone("persist.sys.timezone");
50
51 if ((name = persist_sys_timezone.Get()) != nullptr && strlen(name) > 3) {
52 // POSIX and Java disagree about the sign in a timezone string. For POSIX, "GMT+3" means
53 // "3 hours west/behind", but for Java it means "3 hours east/ahead". Since (a) Java is
54 // the one that matches human expectations and (b) this system property is used directly
55 // by Java, we flip the sign here to translate from Java to POSIX. http://b/25463955.
56 char sign = name[3];
57 if (sign == '-' || sign == '+') {
58 strlcpy(buf, name, sizeof(buf));
59 buf[3] = (sign == '-') ? '+' : '-';
60 name = buf;
61 }
62 }
63 }
64
65 // If the system property is also not available (because you're running AOSP on a WiFi-only
66 // device, say), fall back to GMT.
67 if (name == nullptr) name = "GMT";
68
69 tzsetlcl(name);
70 }
71
72 #if !defined(__ANDROID__)
make_path(const char * path_prefix_variable,const char * path_suffix)73 static char* make_path(const char* path_prefix_variable,
74 const char* path_suffix) {
75 const char* path_prefix = getenv(path_prefix_variable);
76 if (path_prefix == nullptr) {
77 fprintf(stderr, "%s: %s not set!\n", __FUNCTION__, path_prefix_variable);
78 abort();
79 }
80 char* path;
81 if (asprintf(&path, "%s/%s", path_prefix, path_suffix) == -1) {
82 fprintf(stderr, "%s: couldn't allocate \"%s/%s\"\n", __FUNCTION__, path_prefix, path_suffix);
83 abort();
84 }
85 return path;
86 }
87 #endif
88
89 // byte[12] tzdata_version -- "tzdata2012f\0"
90 // int index_offset
91 // int data_offset
92 // int zonetab_offset
93 struct bionic_tzdata_header_t {
94 char tzdata_version[12];
95 int32_t index_offset;
96 int32_t data_offset;
97 int32_t zonetab_offset;
98 };
99 static constexpr size_t NAME_LENGTH = 40;
100 struct index_entry_t {
101 char buf[NAME_LENGTH];
102 int32_t start;
103 int32_t length;
104 int32_t unused; // Was raw GMT offset; always 0 since tzdata2014f (L).
105 };
106
__bionic_open_tzdata_path(const char * path,const char * olson_id,int32_t * entry_length)107 static int __bionic_open_tzdata_path(const char* path,
108 const char* olson_id,
109 int32_t* entry_length) {
110 int fd = TEMP_FAILURE_RETRY(open(path, O_RDONLY | O_CLOEXEC));
111 if (fd == -1) {
112 return -2; // Distinguish failure to find any data from failure to find a specific id.
113 }
114
115 bionic_tzdata_header_t header = {};
116 ssize_t bytes_read = TEMP_FAILURE_RETRY(read(fd, &header, sizeof(header)));
117 if (bytes_read != sizeof(header)) {
118 fprintf(stderr, "%s: could not read header of \"%s\": %s\n",
119 __FUNCTION__, path, (bytes_read == -1) ? strerror(errno) : "short read");
120 close(fd);
121 return -1;
122 }
123
124 if (strncmp(header.tzdata_version, "tzdata", 6) != 0 || header.tzdata_version[11] != 0) {
125 fprintf(stderr, "%s: bad magic in \"%s\": \"%.6s\"\n", __FUNCTION__, path, header.tzdata_version);
126 close(fd);
127 return -1;
128 }
129
130 if (TEMP_FAILURE_RETRY(lseek(fd, ntohl(header.index_offset), SEEK_SET)) == -1) {
131 fprintf(stderr, "%s: couldn't seek to index in \"%s\": %s\n", __FUNCTION__, path, strerror(errno));
132 close(fd);
133 return -1;
134 }
135
136 if (ntohl(header.index_offset) > ntohl(header.data_offset)) {
137 fprintf(stderr, "%s: invalid data and index offsets in \"%s\": %u %u\n",
138 __FUNCTION__, path, ntohl(header.data_offset), ntohl(header.index_offset));
139 close(fd);
140 return -1;
141 }
142 const size_t index_size = ntohl(header.data_offset) - ntohl(header.index_offset);
143 if ((index_size % sizeof(index_entry_t)) != 0) {
144 fprintf(stderr, "%s: invalid index size in \"%s\": %zd\n", __FUNCTION__, path, index_size);
145 close(fd);
146 return -1;
147 }
148
149 off_t specific_zone_offset = -1;
150 char* index = reinterpret_cast<char*>(malloc(index_size));
151 if (index == nullptr) {
152 fprintf(stderr, "%s: couldn't allocate %zd-byte index for \"%s\"\n", __FUNCTION__, index_size, path);
153 close(fd);
154 return -1;
155 }
156 if (TEMP_FAILURE_RETRY(read(fd, index, index_size)) != static_cast<ssize_t>(index_size)) {
157 fprintf(stderr, "%s: could not read index of \"%s\": %s\n",
158 __FUNCTION__, path, (bytes_read == -1) ? strerror(errno) : "short read");
159 free(index);
160 close(fd);
161 return -1;
162 }
163
164 size_t id_count = index_size / sizeof(index_entry_t);
165 index_entry_t* entry = reinterpret_cast<index_entry_t*>(index);
166 for (size_t i = 0; i < id_count; ++i) {
167 char this_id[NAME_LENGTH + 1];
168 memcpy(this_id, entry->buf, NAME_LENGTH);
169 this_id[NAME_LENGTH] = '\0';
170
171 if (strcmp(this_id, olson_id) == 0) {
172 specific_zone_offset = ntohl(entry->start) + ntohl(header.data_offset);
173 *entry_length = ntohl(entry->length);
174 break;
175 }
176
177 ++entry;
178 }
179 free(index);
180
181 if (specific_zone_offset == -1) {
182 close(fd);
183 return -1;
184 }
185
186 if (TEMP_FAILURE_RETRY(lseek(fd, specific_zone_offset, SEEK_SET)) == -1) {
187 fprintf(stderr, "%s: could not seek to %ld in \"%s\": %s\n",
188 __FUNCTION__, specific_zone_offset, path, strerror(errno));
189 close(fd);
190 return -1;
191 }
192
193 // TODO: check that there's TZ_MAGIC at this offset, so we can fall back to the other file if not.
194
195 return fd;
196 }
197
__bionic_open_tzdata(const char * olson_id,int32_t * entry_length)198 int __bionic_open_tzdata(const char* olson_id, int32_t* entry_length) {
199 int fd;
200
201 #if defined(__ANDROID__)
202 // On Android, try the two hard-coded locations.
203 fd = __bionic_open_tzdata_path("/data/misc/zoneinfo/current/tzdata",
204 olson_id, entry_length);
205 if (fd >= 0) return fd;
206
207 fd = __bionic_open_tzdata_path("/system/usr/share/zoneinfo/tzdata",
208 olson_id, entry_length);
209 if (fd >= 0) return fd;
210 #else
211 // On the host, we don't expect those locations to exist, and we're not
212 // worried about security so we trust $ANDROID_DATA and $ANDROID_ROOT to
213 // point us in the right direction.
214 char* path = make_path("ANDROID_DATA", "/misc/zoneinfo/current/tzdata");
215 fd = __bionic_open_tzdata_path(path, olson_id, entry_length);
216 free(path);
217 if (fd >= 0) return fd;
218
219 path = make_path("ANDROID_ROOT", "/usr/share/zoneinfo/tzdata");
220 fd = __bionic_open_tzdata_path(path, olson_id, entry_length);
221 free(path);
222 if (fd >= 0) return fd;
223 #endif
224
225 // Not finding any tzdata is more serious that not finding a specific zone,
226 // and worth logging.
227 if (fd == -2) {
228 // The first thing that 'recovery' does is try to format the current time. It doesn't have
229 // any tzdata available, so we must not abort here --- doing so breaks the recovery image!
230 fprintf(stderr, "%s: couldn't find any tzdata when looking for %s!\n", __FUNCTION__, olson_id);
231 }
232
233 return fd;
234 }
235