/*
* Copyright (C) 2017 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <arpa/inet.h> // For ntohl(3).
#include <errno.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdlib.h>
#include <unistd.h>
#include "private/CachedProperty.h"
extern "C" void tzset_unlocked(void);
extern "C" int __bionic_open_tzdata(const char*, int32_t*);
extern "C" void tzsetlcl(char const*);
void tzset_unlocked() {
// The TZ environment variable is meant to override the system-wide setting.
const char* name = getenv("TZ");
char buf[PROP_VALUE_MAX];
// If that's not set, look at the "persist.sys.timezone" system property.
if (name == nullptr) {
static CachedProperty persist_sys_timezone("persist.sys.timezone");
if ((name = persist_sys_timezone.Get()) != nullptr && strlen(name) > 3) {
// POSIX and Java disagree about the sign in a timezone string. For POSIX, "GMT+3" means
// "3 hours west/behind", but for Java it means "3 hours east/ahead". Since (a) Java is
// the one that matches human expectations and (b) this system property is used directly
// by Java, we flip the sign here to translate from Java to POSIX. http://b/25463955.
char sign = name[3];
if (sign == '-' || sign == '+') {
strlcpy(buf, name, sizeof(buf));
buf[3] = (sign == '-') ? '+' : '-';
name = buf;
}
}
}
// If the system property is also not available (because you're running AOSP on a WiFi-only
// device, say), fall back to GMT.
if (name == nullptr) name = "GMT";
tzsetlcl(name);
}
#if !defined(__ANDROID__)
static char* make_path(const char* path_prefix_variable,
const char* path_suffix) {
const char* path_prefix = getenv(path_prefix_variable);
if (path_prefix == nullptr) {
fprintf(stderr, "%s: %s not set!\n", __FUNCTION__, path_prefix_variable);
abort();
}
char* path;
if (asprintf(&path, "%s/%s", path_prefix, path_suffix) == -1) {
fprintf(stderr, "%s: couldn't allocate \"%s/%s\"\n", __FUNCTION__, path_prefix, path_suffix);
abort();
}
return path;
}
#endif
// byte[12] tzdata_version -- "tzdata2012f\0"
// int index_offset
// int data_offset
// int zonetab_offset
struct bionic_tzdata_header_t {
char tzdata_version[12];
int32_t index_offset;
int32_t data_offset;
int32_t zonetab_offset;
};
static constexpr size_t NAME_LENGTH = 40;
struct index_entry_t {
char buf[NAME_LENGTH];
int32_t start;
int32_t length;
int32_t unused; // Was raw GMT offset; always 0 since tzdata2014f (L).
};
static int __bionic_open_tzdata_path(const char* path,
const char* olson_id,
int32_t* entry_length) {
int fd = TEMP_FAILURE_RETRY(open(path, O_RDONLY | O_CLOEXEC));
if (fd == -1) {
return -2; // Distinguish failure to find any data from failure to find a specific id.
}
bionic_tzdata_header_t header = {};
ssize_t bytes_read = TEMP_FAILURE_RETRY(read(fd, &header, sizeof(header)));
if (bytes_read != sizeof(header)) {
fprintf(stderr, "%s: could not read header of \"%s\": %s\n",
__FUNCTION__, path, (bytes_read == -1) ? strerror(errno) : "short read");
close(fd);
return -1;
}
if (strncmp(header.tzdata_version, "tzdata", 6) != 0 || header.tzdata_version[11] != 0) {
fprintf(stderr, "%s: bad magic in \"%s\": \"%.6s\"\n", __FUNCTION__, path, header.tzdata_version);
close(fd);
return -1;
}
if (TEMP_FAILURE_RETRY(lseek(fd, ntohl(header.index_offset), SEEK_SET)) == -1) {
fprintf(stderr, "%s: couldn't seek to index in \"%s\": %s\n", __FUNCTION__, path, strerror(errno));
close(fd);
return -1;
}
if (ntohl(header.index_offset) > ntohl(header.data_offset)) {
fprintf(stderr, "%s: invalid data and index offsets in \"%s\": %u %u\n",
__FUNCTION__, path, ntohl(header.data_offset), ntohl(header.index_offset));
close(fd);
return -1;
}
const size_t index_size = ntohl(header.data_offset) - ntohl(header.index_offset);
if ((index_size % sizeof(index_entry_t)) != 0) {
fprintf(stderr, "%s: invalid index size in \"%s\": %zd\n", __FUNCTION__, path, index_size);
close(fd);
return -1;
}
off_t specific_zone_offset = -1;
char* index = reinterpret_cast<char*>(malloc(index_size));
if (index == nullptr) {
fprintf(stderr, "%s: couldn't allocate %zd-byte index for \"%s\"\n", __FUNCTION__, index_size, path);
close(fd);
return -1;
}
if (TEMP_FAILURE_RETRY(read(fd, index, index_size)) != static_cast<ssize_t>(index_size)) {
fprintf(stderr, "%s: could not read index of \"%s\": %s\n",
__FUNCTION__, path, (bytes_read == -1) ? strerror(errno) : "short read");
free(index);
close(fd);
return -1;
}
size_t id_count = index_size / sizeof(index_entry_t);
index_entry_t* entry = reinterpret_cast<index_entry_t*>(index);
for (size_t i = 0; i < id_count; ++i) {
char this_id[NAME_LENGTH + 1];
memcpy(this_id, entry->buf, NAME_LENGTH);
this_id[NAME_LENGTH] = '\0';
if (strcmp(this_id, olson_id) == 0) {
specific_zone_offset = ntohl(entry->start) + ntohl(header.data_offset);
*entry_length = ntohl(entry->length);
break;
}
++entry;
}
free(index);
if (specific_zone_offset == -1) {
close(fd);
return -1;
}
if (TEMP_FAILURE_RETRY(lseek(fd, specific_zone_offset, SEEK_SET)) == -1) {
fprintf(stderr, "%s: could not seek to %ld in \"%s\": %s\n",
__FUNCTION__, specific_zone_offset, path, strerror(errno));
close(fd);
return -1;
}
// TODO: check that there's TZ_MAGIC at this offset, so we can fall back to the other file if not.
return fd;
}
int __bionic_open_tzdata(const char* olson_id, int32_t* entry_length) {
int fd;
#if defined(__ANDROID__)
// On Android, try the two hard-coded locations.
fd = __bionic_open_tzdata_path("/data/misc/zoneinfo/current/tzdata",
olson_id, entry_length);
if (fd >= 0) return fd;
fd = __bionic_open_tzdata_path("/system/usr/share/zoneinfo/tzdata",
olson_id, entry_length);
if (fd >= 0) return fd;
#else
// On the host, we don't expect those locations to exist, and we're not
// worried about security so we trust $ANDROID_DATA and $ANDROID_ROOT to
// point us in the right direction.
char* path = make_path("ANDROID_DATA", "/misc/zoneinfo/current/tzdata");
fd = __bionic_open_tzdata_path(path, olson_id, entry_length);
free(path);
if (fd >= 0) return fd;
path = make_path("ANDROID_ROOT", "/usr/share/zoneinfo/tzdata");
fd = __bionic_open_tzdata_path(path, olson_id, entry_length);
free(path);
if (fd >= 0) return fd;
#endif
// Not finding any tzdata is more serious that not finding a specific zone,
// and worth logging.
if (fd == -2) {
// The first thing that 'recovery' does is try to format the current time. It doesn't have
// any tzdata available, so we must not abort here --- doing so breaks the recovery image!
fprintf(stderr, "%s: couldn't find any tzdata when looking for %s!\n", __FUNCTION__, olson_id);
}
return fd;
}