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