libc/tzcode/bionic.cpp - platform/bionic - Git at Google

 /*
  * 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;

   // Try the three locations for the tzdata file in a strict order:
   // 1: The O-MR1 time zone updates via APK update mechanism. This is
   //    tried first because it allows us to test that the time zone updates
   //    via APK mechanism still works even on devices with the time zone
   //    module.
   // 2: The time zone data module which contains the main copy. This is the
   //    common case.
   // 3: The ultimate fallback: the non-updatable copy in /system.

 #if defined(__ANDROID__)
   // On Android devices, bionic has to work even if exec takes place without
   // environment variables set. So, all paths are hardcoded here.

   fd = __bionic_open_tzdata_path("/data/misc/zoneinfo/current/tzdata",
                                  olson_id, entry_length);
   if (fd >= 0) return fd;

   fd = __bionic_open_tzdata_path("/apex/com.android.tzdata/etc/tz/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 the hard-coded locations above to exist, and
   // we're not worried about security so we trust $ANDROID_DATA,
   // $ANDROID_TZDATA_ROOT, and $ANDROID_ROOT to point us in the right direction
   // instead.

   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_TZDATA_ROOT", "/etc/tz/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;
 }
	/*
	* 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;

	// Try the three locations for the tzdata file in a strict order:
	// 1: The O-MR1 time zone updates via APK update mechanism. This is
	// tried first because it allows us to test that the time zone updates
	// via APK mechanism still works even on devices with the time zone
	// module.
	// 2: The time zone data module which contains the main copy. This is the
	// common case.
	// 3: The ultimate fallback: the non-updatable copy in /system.

	#if defined(__ANDROID__)
	// On Android devices, bionic has to work even if exec takes place without
	// environment variables set. So, all paths are hardcoded here.

	fd = __bionic_open_tzdata_path("/data/misc/zoneinfo/current/tzdata",
	olson_id, entry_length);
	if (fd >= 0) return fd;

	fd = __bionic_open_tzdata_path("/apex/com.android.tzdata/etc/tz/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 the hard-coded locations above to exist, and
	// we're not worried about security so we trust $ANDROID_DATA,
	// $ANDROID_TZDATA_ROOT, and $ANDROID_ROOT to point us in the right direction
	// instead.

	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_TZDATA_ROOT", "/etc/tz/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;
	}