parse_tz.c cpanel version shipped with cpeasyapache

parse_tz.c

/*
   +----------------------------------------------------------------------+
   | PHP Version 5                                                        |
   +----------------------------------------------------------------------+
   | Copyright (c) 1997-2013 The PHP Group                                |
   +----------------------------------------------------------------------+
   | This source file is subject to version 3.01 of the PHP license,      |
   | that is bundled with this package in the file LICENSE, and is        |
   | available through the world-wide-web at the following url:           |
   | http://www.php.net/license/3_01.txt                                  |
   | If you did not receive a copy of the PHP license and are unable to   |
   | obtain it through the world-wide-web, please send a note to          |
   | license@php.net so we can mail you a copy immediately.               |
   +----------------------------------------------------------------------+
   | Authors: Derick Rethans <derick@derickrethans.nl>                    |
   +----------------------------------------------------------------------+
 */

/* $Id$ */

#include "timelib.h"

#define HAVE_SYSTEM_TZDATA 1
#ifdef HAVE_SYSTEM_TZDATA
#include <sys/mman.h>
#include <sys/stat.h>
#include <limits.h>
#include <fcntl.h>
#include <unistd.h>

#include "php_scandir.h"
#endif

#include <stdio.h>

#ifdef HAVE_LOCALE_H
#include <locale.h>
#endif

#ifdef HAVE_STRING_H
#include <string.h>
#else
#include <strings.h>
#endif

#ifndef HAVE_SYSTEM_TZDATA
#include "timezonedb.h"
#endif

#include <ctype.h>

#if (defined(__APPLE__) || defined(__APPLE_CC__)) && (defined(__BIG_ENDIAN__) || defined(__LITTLE_ENDIAN__))
# if defined(__LITTLE_ENDIAN__)
#  undef WORDS_BIGENDIAN
# else 
#  if defined(__BIG_ENDIAN__)
#   define WORDS_BIGENDIAN
#  endif
# endif
#endif

#ifdef WORDS_BIGENDIAN
#define timelib_conv_int(l) (l)
#else
#define timelib_conv_int(l) ((l & 0x000000ff) << 24) + ((l & 0x0000ff00) << 8) + ((l & 0x00ff0000) >> 8) + ((l & 0xff000000) >> 24)
#endif

static void read_preamble(const unsigned char **tzf, timelib_tzinfo *tz)
{
	if (memcmp(tzf, "TZif", 4) == 0) {
		*tzf += 20;
		return;
	}
    
	/* skip ID */
	*tzf += 4;
	
	/* read BC flag */
	tz->bc = (**tzf == '\1');
	*tzf += 1;

	/* read country code */
	memcpy(tz->location.country_code, *tzf, 2);
	tz->location.country_code[2] = '\0';
	*tzf += 2;

	/* skip read of preamble */
	*tzf += 13;
}

static void read_header(const unsigned char **tzf, timelib_tzinfo *tz)
{
	uint32_t buffer[6];

	memcpy(&buffer, *tzf, sizeof(buffer));
	tz->ttisgmtcnt = timelib_conv_int(buffer[0]);
	tz->ttisstdcnt = timelib_conv_int(buffer[1]);
	tz->leapcnt    = timelib_conv_int(buffer[2]);
	tz->timecnt    = timelib_conv_int(buffer[3]);
	tz->typecnt    = timelib_conv_int(buffer[4]);
	tz->charcnt    = timelib_conv_int(buffer[5]);
	*tzf += sizeof(buffer);
}

static void read_transistions(const unsigned char **tzf, timelib_tzinfo *tz)
{
	int32_t *buffer = NULL;
	uint32_t i;
	unsigned char *cbuffer = NULL;

	if (tz->timecnt) {
		buffer = (int32_t*) malloc(tz->timecnt * sizeof(int32_t));
		if (!buffer) {
			return;
		}
		memcpy(buffer, *tzf, sizeof(int32_t) * tz->timecnt);
		*tzf += (sizeof(int32_t) * tz->timecnt);
		for (i = 0; i < tz->timecnt; i++) {
			buffer[i] = timelib_conv_int(buffer[i]);
		}

		cbuffer = (unsigned char*) malloc(tz->timecnt * sizeof(unsigned char));
		if (!cbuffer) {
			free(buffer);
			return;
		}
		memcpy(cbuffer, *tzf, sizeof(unsigned char) * tz->timecnt);
		*tzf += sizeof(unsigned char) * tz->timecnt;
	}
	
	tz->trans = buffer;
	tz->trans_idx = cbuffer;
}

static void read_types(const unsigned char **tzf, timelib_tzinfo *tz)
{
	unsigned char *buffer;
	int32_t *leap_buffer;
	unsigned int i, j;

	buffer = (unsigned char*) malloc(tz->typecnt * sizeof(unsigned char) * 6);
	if (!buffer) {
		return;
	}
	memcpy(buffer, *tzf, sizeof(unsigned char) * 6 * tz->typecnt);
	*tzf += sizeof(unsigned char) * 6 * tz->typecnt;

	tz->type = (ttinfo*) malloc(tz->typecnt * sizeof(struct ttinfo));
	if (!tz->type) {
		free(buffer);
		return;
	}

	for (i = 0; i < tz->typecnt; i++) {
		j = i * 6;
		tz->type[i].offset = (buffer[j] * 16777216) + (buffer[j + 1] * 65536) + (buffer[j + 2] * 256) + buffer[j + 3];
		tz->type[i].isdst = buffer[j + 4];
		tz->type[i].abbr_idx = buffer[j + 5];
	}
	free(buffer);

	tz->timezone_abbr = (char*) malloc(tz->charcnt);
	if (!tz->timezone_abbr) {
		return;
	}
	memcpy(tz->timezone_abbr, *tzf, sizeof(char) * tz->charcnt);
	*tzf += sizeof(char) * tz->charcnt;

	if (tz->leapcnt) {
		leap_buffer = (int32_t *) malloc(tz->leapcnt * 2 * sizeof(int32_t));
		if (!leap_buffer) {
			return;
		}
		memcpy(leap_buffer, *tzf, sizeof(int32_t) * tz->leapcnt * 2);
		*tzf += sizeof(int32_t) * tz->leapcnt * 2;

		tz->leap_times = (tlinfo*) malloc(tz->leapcnt * sizeof(tlinfo));
		if (!tz->leap_times) {
			free(leap_buffer);
			return;
		}
		for (i = 0; i < tz->leapcnt; i++) {
			tz->leap_times[i].trans = timelib_conv_int(leap_buffer[i * 2]);
			tz->leap_times[i].offset = timelib_conv_int(leap_buffer[i * 2 + 1]);
		}
		free(leap_buffer);
	}

	if (tz->ttisstdcnt) {
		buffer = (unsigned char*) malloc(tz->ttisstdcnt * sizeof(unsigned char));
		if (!buffer) {
			return;
		}
		memcpy(buffer, *tzf, sizeof(unsigned char) * tz->ttisstdcnt);
		*tzf += sizeof(unsigned char) * tz->ttisstdcnt;

		for (i = 0; i < tz->ttisstdcnt; i++) {
			tz->type[i].isstdcnt = buffer[i];
		}
		free(buffer);
	}

	if (tz->ttisgmtcnt) {
		buffer = (unsigned char*) malloc(tz->ttisgmtcnt * sizeof(unsigned char));
		if (!buffer) {
			return;
		}
		memcpy(buffer, *tzf, sizeof(unsigned char) * tz->ttisgmtcnt);
		*tzf += sizeof(unsigned char) * tz->ttisgmtcnt;

		for (i = 0; i < tz->ttisgmtcnt; i++) {
			tz->type[i].isgmtcnt = buffer[i];
		}
		free(buffer);
	}
}

static void read_location(const unsigned char **tzf, timelib_tzinfo *tz)
{
	uint32_t buffer[3];
	uint32_t comments_len;

	memcpy(&buffer, *tzf, sizeof(buffer));
	tz->location.latitude = timelib_conv_int(buffer[0]);
	tz->location.latitude = (tz->location.latitude / 100000) - 90;
	tz->location.longitude = timelib_conv_int(buffer[1]);
	tz->location.longitude = (tz->location.longitude / 100000) - 180;
	comments_len = timelib_conv_int(buffer[2]);
	*tzf += sizeof(buffer);

	tz->location.comments = malloc(comments_len + 1);
	memcpy(tz->location.comments, *tzf, comments_len);
	tz->location.comments[comments_len] = '\0';
	*tzf += comments_len;
}

void timelib_dump_tzinfo(timelib_tzinfo *tz)
{
	uint32_t i;

	printf("Country Code:      %s\n", tz->location.country_code);
	printf("Geo Location:      %f,%f\n", tz->location.latitude, tz->location.longitude);
	printf("Comments:\n%s\n",          tz->location.comments);
	printf("BC:                %s\n",  tz->bc ? "" : "yes");
	printf("UTC/Local count:   %lu\n", (unsigned long) tz->ttisgmtcnt);
	printf("Std/Wall count:    %lu\n", (unsigned long) tz->ttisstdcnt);
	printf("Leap.sec. count:   %lu\n", (unsigned long) tz->leapcnt);
	printf("Trans. count:      %lu\n", (unsigned long) tz->timecnt);
	printf("Local types count: %lu\n", (unsigned long) tz->typecnt);
	printf("Zone Abbr. count:  %lu\n", (unsigned long) tz->charcnt);

	printf ("%8s (%12s) = %3d [%5ld %1d %3d '%s' (%d,%d)]\n",
		"", "", 0,
		(long int) tz->type[0].offset,
		tz->type[0].isdst,
		tz->type[0].abbr_idx,
		&tz->timezone_abbr[tz->type[0].abbr_idx],
		tz->type[0].isstdcnt,
		tz->type[0].isgmtcnt
		);
	for (i = 0; i < tz->timecnt; i++) {
		printf ("%08X (%12d) = %3d [%5ld %1d %3d '%s' (%d,%d)]\n",
			tz->trans[i], tz->trans[i], tz->trans_idx[i],
			(long int) tz->type[tz->trans_idx[i]].offset,
			tz->type[tz->trans_idx[i]].isdst,
			tz->type[tz->trans_idx[i]].abbr_idx,
			&tz->timezone_abbr[tz->type[tz->trans_idx[i]].abbr_idx],
			tz->type[tz->trans_idx[i]].isstdcnt,
			tz->type[tz->trans_idx[i]].isgmtcnt
			);
	}
	for (i = 0; i < tz->leapcnt; i++) {
		printf ("%08X (%12ld) = %d\n",
			tz->leap_times[i].trans,
			(long) tz->leap_times[i].trans,
			tz->leap_times[i].offset);
	}
}

#ifdef HAVE_SYSTEM_TZDATA

#ifdef HAVE_SYSTEM_TZDATA_PREFIX
#define ZONEINFO_PREFIX HAVE_SYSTEM_TZDATA_PREFIX
#else
#define ZONEINFO_PREFIX "/usr/share/zoneinfo"
#endif

/* Hash table entry for the cache of the zone.tab mapping table. */
struct location_info {
	char code[2]; /* Country code. */
	double latitude, longitude;
	char name[64];
	char *comment;
	struct location_info *next;
};

/* System timezone database pointer. */
static const timelib_tzdb *timezonedb_system = NULL;

/* Cache of zone.tab location data. */
static struct location_info **system_location_table;

/* Size of the zone.tab hash table; a random-ish prime big enough to
 * prevent too many collisions. */
#define LOCINFO_HASH_SIZE (1021)

/* Hash function for indexing the location_info hash table. */
static uint32_t tz_hash(const char *str)
{
	const unsigned char *p = (const unsigned char *)str;
	uint32_t hash = 5381;
	int c;
	
	while ((c = *p++) != '\0') {
		hash = (hash << 5) ^ hash ^ c;
	}
	
	return hash % LOCINFO_HASH_SIZE;
}

/* Parse an ISO-6709 co-ordinate as used in zone.tab. Returns end of
 * the parsed string on success, or NULL on parse error.  On success,
 * writes the parsed number to *result. */
static char *parse_iso6709(char *p, double *result)
{
	double v, sign;
	char *pend;
	size_t len;

	if (*p == '+')
		sign = 1.0;
	else if (*p == '-')
		sign = -1.0;
	else
		return NULL;

	p++;
	for (pend = p; *pend >= '0' && *pend <= '9'; pend++)
		;;

	/* Annoying encoding used by zone.tab has no decimal point, so use
	 * the length to determine the format:
	 * 
	 * 4 = DDMM
	 * 5 = DDDMM
	 * 6 = DDMMSS
	 * 7 = DDDMMSS
	 */
	len = pend - p;
	if (len < 4 || len > 7) {
		return NULL;
	}

	/* p => [D]DD */
	v = (p[0] - '0') * 10.0 + (p[1] - '0');
	p += 2;
	if (len == 5 || len == 7)
		v = v * 10.0 + (*p++ - '0');
	/* p => MM[SS] */
	v += (10.0 * (p[0] - '0')
		  + p[1] - '0') / 60.0;
	p += 2;
	/* p => [SS] */
	if (len > 5) {
		v += (10.0 * (p[0] - '0')
			  + p[1] - '0') / 3600.0;
		p += 2;
	}

	/* Round to five decimal place, not because it's a good idea,
	 * but, because the builtin data uses rounded data, so, match
	 * that. */
	*result = sign * (int)(v * 100000.0 + 0.5) / 100000.0;

	return p;
}

/* This function parses the zone.tab file to build up the mapping of
 * timezone to country code and geographic location, and returns a
 * hash table.	The hash table is indexed by the function:
 *
 *	 tz_hash(timezone-name)
 */
static struct location_info **create_location_table(void)
{
	struct location_info **li, *i;
	char zone_tab[PATH_MAX];
	char line[512];
	FILE *fp;

	strncpy(zone_tab, ZONEINFO_PREFIX "/zone.tab", sizeof zone_tab);

	fp = fopen(zone_tab, "r");
	if (!fp) {
		return NULL;
	}

	li = calloc(LOCINFO_HASH_SIZE, sizeof *li);

	while (fgets(line, sizeof line, fp)) {
		char *p = line, *code, *name, *comment;
		uint32_t hash;
		double latitude, longitude;

		while (isspace(*p))
			p++;

		if (*p == '#' || *p == '\0' || *p == '\n')
			continue;
		
		if (!isalpha(p[0]) || !isalpha(p[1]) || p[2] != '\t')
			continue;
		
		/* code => AA */
		code = p;
		p[2] = 0;
		p += 3;

		/* coords => [+-][D]DDMM[SS][+-][D]DDMM[SS] */
		p = parse_iso6709(p, &latitude);
		if (!p) {
			continue;
		}
		p = parse_iso6709(p, &longitude);
		if (!p) {
			continue;
		}

		if (!p || *p != '\t') {
			continue;
		}

		/* name = string */
		name = ++p;
		while (*p != '\t' && *p && *p != '\n')
			p++;

		*p++ = '\0';

		/* comment = string */
		comment = p;
		while (*p != '\t' && *p && *p != '\n')
			p++;

		if (*p == '\n' || *p == '\t')
			*p = '\0';
		
		hash = tz_hash(name);
		i = malloc(sizeof *i);
		memcpy(i->code, code, 2);
		strncpy(i->name, name, sizeof i->name);
		i->comment = strdup(comment);
		i->longitude = longitude;
		i->latitude = latitude;
		i->next = li[hash];
		li[hash] = i;
		/* printf("%s [%u, %f, %f]\n", name, hash, latitude, longitude); */
	}

	fclose(fp);

	return li;
}

/* Return location info from hash table, using given timezone name.
 * Returns NULL if the name could not be found. */
const struct location_info *find_zone_info(struct location_info **li, 
										   const char *name)
{
	uint32_t hash = tz_hash(name);
	const struct location_info *l;

	if (!li) {
		return NULL;
	}

	for (l = li[hash]; l; l = l->next) {
		if (strcasecmp(l->name, name) == 0)
			return l;
	}

	return NULL;
}	 

/* Filter out some non-tzdata files and the posix/right databases, if
 * present. */
static int index_filter(const struct dirent *ent)
{
	return strcmp(ent->d_name, ".") != 0
		&& strcmp(ent->d_name, "..") != 0
		&& strcmp(ent->d_name, "posix") != 0
		&& strcmp(ent->d_name, "posixrules") != 0
		&& strcmp(ent->d_name, "right") != 0
		&& strstr(ent->d_name, ".tab") == NULL;
}

/* Comparison callback for qsort(), used to alpha-sort the index
 * array by timezone name. */
static int sysdbcmp(const void *first, const void *second)
{
	const timelib_tzdb_index_entry *alpha = first, *beta = second;
	
	return strcmp(alpha->id, beta->id);
}


/* Create the zone identifier index by trawling the filesystem. */
static void create_zone_index(timelib_tzdb *db)
{
	size_t dirstack_size,  dirstack_top;
	size_t index_size, index_next;
	timelib_tzdb_index_entry *db_index;
	char **dirstack;

	/* LIFO stack to hold directory entries to scan; each slot is a
	 * directory name relative to the zoneinfo prefix. */
	dirstack_size = 32;
	dirstack = malloc(dirstack_size * sizeof *dirstack);
	dirstack_top = 1;
	dirstack[0] = strdup("");
	
	/* Index array. */
	index_size = 64;
	db_index = malloc(index_size * sizeof *db_index);
	index_next = 0;

	do {
		struct dirent **ents;
		char name[PATH_MAX], *top;
		int count;

		/* Pop the top stack entry, and iterate through its contents. */
		top = dirstack[--dirstack_top];
		snprintf(name, sizeof name, ZONEINFO_PREFIX "/%s", top);

		count = php_scandir(name, &ents, index_filter, php_alphasort);

		while (count > 0) {
			struct stat st;
			const char *leaf = ents[count - 1]->d_name;

			snprintf(name, sizeof name, ZONEINFO_PREFIX "/%s/%s", 
				 top, leaf);
			
			if (strlen(name) && stat(name, &st) == 0) {
				/* Name, relative to the zoneinfo prefix. */
				const char *root = top;

				if (root[0] == '/') root++;

				snprintf(name, sizeof name, "%s%s%s", root, 
					 *root ? "/": "", leaf);

				if (S_ISDIR(st.st_mode)) {
					if (dirstack_top == dirstack_size) {
						dirstack_size *= 2;
						dirstack = realloc(dirstack, 
										   dirstack_size * sizeof *dirstack);
					}
					dirstack[dirstack_top++] = strdup(name);
				}
				else {
					if (index_next == index_size) {
						index_size *= 2;
						db_index = realloc(db_index,
										   index_size * sizeof *db_index);
					}

					db_index[index_next++].id = strdup(name);
				}
			}

			free(ents[--count]);
		}
		
		if (count != -1) free(ents);
		free(top);
	} while (dirstack_top);

	/* Alpha-sort the index array; shouldn't be technically necessary
	 * but some of the test cases rely on this, and, it matches the
	 * builtin database. */
	qsort(db_index, index_next, sizeof *db_index, sysdbcmp);
	
	db->index = db_index;
	db->index_size = index_next;

	free(dirstack);
}

#define FAKE_HEADER "1234\0??\1??"
#define FAKE_BC_POS (0)
#define FAKE_UTC_POS (7 - 4)

/* Create a fake data segment for database 'sysdb'.   This mocks
 * up a fake ->data segment for the given timezone database. 
 * php_date.c::timezone_identifiers_list() looks at data[pos + 4]
 * through data[pos + 6] to compare the country code and BC flag, 
 * which are stored in the builtin data array like:
 *
 *    (pos + 4) => BC flag
 *    (pos + 5, pos + 6) => Two chars of country code
 *
 * where pos is the index corresponding to the timezone name.
 *
 * Timezone names are classified here into three types:
 *    1) UTC, which is special
 *    2) "normal" zone names
 *    3) "backwards-compat" zone names
 *
 * (boolean logic of the BC flag seems to be inverted, but hey)
 *
 * UTC is special since it has BC=\1, code = "??"
 * "normal" zones exist in zone.tab and have the given c-code and BC=\1
 * "backwards-compat" zones don't exist in zone.tab and have BC=\0
 *
 * Since UTC and the BC zones are constant, they are encoded in the
 * FAKE_HEADER prefix, and pos pointers index into that.
 *
 * FAKE_HEADER is hence four random bytes, then the BC zone segment
 * (three bytes), then the UTC zone segment (another three).
 *
 * For all "normal" zones, three bytes are appended to the data array;
 * the BC flag, always 1, and the two bytes of country code.
 */
static void fake_data_segment(timelib_tzdb *sysdb,
							  struct location_info **info)
{
	size_t n;
	char *data, *p;
	
	/* Worst case maximum is 3 bytes per zone, plus the header. */
	data = malloc((3 * sysdb->index_size) + sizeof(FAKE_HEADER) - 1);
	
	/* Append the fake header, p then = next byte */
	p = mempcpy(data, FAKE_HEADER, sizeof(FAKE_HEADER) - 1);
	
	for (n = 0; n < sysdb->index_size; n++) {
		const struct location_info *li;
		timelib_tzdb_index_entry *ent;
		
		/* Lost const'ness since we're modifying the pos pointer. */
		ent = (timelib_tzdb_index_entry *)&sysdb->index[n];
		
		/* Lookup the timezone name in the hash table. */
		if (strcmp(ent->id, "UTC") == 0) {
			ent->pos = FAKE_UTC_POS;
			continue;
		}
		
		li = find_zone_info(info, ent->id);
		if (li) {
			/* If found, append the BC byte and the country code; set
			 * the position index for the timezone to point to
			 * this.  */
			ent->pos = (p - data) - 4;
			*p++ = '\x01';
			*p++ = li->code[0];
			*p++ = li->code[1];
		}
		else {
			/* If not found, the timezone data can
			 * point at the header. */
			ent->pos = 0;
		}
	}
	
	/* Store the fake data array */
	sysdb->data = (unsigned char *)data;
}

/* Evaluates to true if given timezone name is valid. */
#define is_valid_tz_name(tz_) (tz_[0] && strstr(tz_, "..") == NULL)

/* Return the mmap()ed tzfile if found, else NULL.	On success, the
 * length of the mapped data is placed in *length. */
static char *map_tzfile(const char *timezone, size_t *length)
{
	char fname[PATH_MAX];
	struct stat st;
	char *p;
	int fd;
	
	if (!is_valid_tz_name(timezone)) {
		return NULL;
	}

	snprintf(fname, sizeof fname, ZONEINFO_PREFIX "/%s", timezone);
	
	fd = open(fname, O_RDONLY);
	if (fd == -1) {
		return NULL;
	} else if (fstat(fd, &st) != 0 || st.st_size < 21) {
		close(fd);
		return NULL;
	}

	*length = st.st_size;
	p = mmap(NULL, st.st_size, PROT_READ, MAP_SHARED, fd, 0);
	close(fd);
	
	return p != MAP_FAILED ? p : NULL;
}
#endif

/* seek_to_tz_position() for a builtin/external database. */
static int inmem_seek_to_tz_position(const unsigned char **tzf, 
									 char *timezone, const timelib_tzdb *tzdb)
{
	int left = 0, right = tzdb->index_size - 1;
#ifdef HAVE_SETLOCALE
	char *cur_locale = NULL, *tmp;

	tmp = setlocale(LC_CTYPE, NULL);
	if (tmp) {
		cur_locale = strdup(tmp);
	}
	setlocale(LC_CTYPE, "C");
#endif	

	do {
		int mid = ((unsigned)left + right) >> 1;
		int cmp = strcasecmp(timezone, tzdb->index[mid].id);

		if (cmp < 0) {
			right = mid - 1;
		} else if (cmp > 0) {
			left = mid + 1;
		} else { /* (cmp == 0) */
			(*tzf) = &(tzdb->data[tzdb->index[mid].pos]);
#ifdef HAVE_SETLOCALE
			setlocale(LC_CTYPE, cur_locale);
			if (cur_locale) free(cur_locale);
#endif	
			return 1;
		}

	} while (left <= right);

#ifdef HAVE_SETLOCALE
	setlocale(LC_CTYPE, cur_locale);
	if (cur_locale) free(cur_locale);
#endif	
	return 0;
}

/* Modified seek_to_tz_position wrapper which handles the system
 * database and the builtin/external databases in the same way.
 * Returns zero on failure on non-zero on success.  On success, (*map,
 * *maplen) is an mmap'ed region if *map is non-NULL, and must be
 * munmaped after use.  */
static int seek_to_tz_position(const unsigned char **tzf, char *timezone, 
							   char **map, size_t *maplen,
							   const timelib_tzdb *tzdb)
{
#ifdef HAVE_SYSTEM_TZDATA
	if (tzdb == timezonedb_system) {
		char *orig;

		orig = map_tzfile(timezone, maplen);
		if (orig == NULL) {
			return 0;
		}
		
		(*tzf) = (unsigned char *)orig ;
		*map = orig;
				
		return 1;
	}
	else 
#endif
	{
		return inmem_seek_to_tz_position(tzf, timezone, tzdb);
	}
}

const timelib_tzdb *timelib_builtin_db(void)
{
#ifdef HAVE_SYSTEM_TZDATA
	if (timezonedb_system == NULL) {
		timelib_tzdb *tmp = malloc(sizeof *tmp);

		tmp->version = "0.system";
		tmp->data = NULL;
		create_zone_index(tmp);
		system_location_table = create_location_table();
		fake_data_segment(tmp, system_location_table);
		timezonedb_system = tmp;
	}
			
	return timezonedb_system;
#else
	return &timezonedb_builtin;
#endif
}

const timelib_tzdb_index_entry *timelib_timezone_builtin_identifiers_list(int *count)
{
#ifdef HAVE_SYSTEM_TZDATA
	*count = timezonedb_system->index_size;
	return timezonedb_system->index;
#else
	*count = sizeof(timezonedb_idx_builtin) / sizeof(*timezonedb_idx_builtin);
	return timezonedb_idx_builtin;
#endif
}

int timelib_timezone_id_is_valid(char *timezone, const timelib_tzdb *tzdb)
{
	const unsigned char *tzf;

#ifdef HAVE_SYSTEM_TZDATA
	if (tzdb == timezonedb_system) {
		char fname[PATH_MAX];
		struct stat st;
		
		if (!is_valid_tz_name(timezone)) {
			return 0;
		}
        
		snprintf(fname, sizeof fname, ZONEINFO_PREFIX "/%s", timezone);
        
		return stat(fname, &st) == 0 && S_ISREG(st.st_mode);
	}
#endif

	return (inmem_seek_to_tz_position(&tzf, timezone, tzdb));
}

timelib_tzinfo *timelib_parse_tzfile(char *timezone, const timelib_tzdb *tzdb)
{
	const unsigned char *tzf;
	char *memmap = NULL;
	size_t maplen;
	timelib_tzinfo *tmp;

	if (seek_to_tz_position(&tzf, timezone, &memmap, &maplen, tzdb)) {
		tmp = timelib_tzinfo_ctor(timezone);

		read_preamble(&tzf, tmp);
		read_header(&tzf, tmp);
		read_transistions(&tzf, tmp);
		read_types(&tzf, tmp);

#ifdef HAVE_SYSTEM_TZDATA
		if (memmap) {
			const struct location_info *li;
			
			/* TZif-style - grok the location info from the system database,
			 * if possible. */
			if ((li = find_zone_info(system_location_table, timezone)) != NULL) {
				tmp->location.comments = strdup(li->comment);
				strncpy(tmp->location.country_code, li->code, 2);
				tmp->location.longitude = li->longitude;
				tmp->location.latitude = li->latitude;
				tmp->bc = 1;
			}
			else {
				strcpy(tmp->location.country_code, "??");
				tmp->bc = 0;
				tmp->location.comments = strdup("");
			}

			/* Now done with the mmap segment - discard it. */
			munmap(memmap, maplen);
		}
		else
#endif
		{
			/* PHP-style - use the embedded info. */
			read_location(&tzf, tmp);
		}
	} else {
		tmp = NULL;
	}

	return tmp;
}

static ttinfo* fetch_timezone_offset(timelib_tzinfo *tz, timelib_sll ts, timelib_sll *transition_time)
{
	uint32_t i;

	/* If there is no transistion time, we pick the first one, if that doesn't
	 * exist we return NULL */
	if (!tz->timecnt || !tz->trans) {
		*transition_time = 0;
		if (tz->typecnt == 1) {
			return &(tz->type[0]);
		}
		return NULL;
	}

	/* If the TS is lower than the first transistion time, then we scan over
	 * all the transistion times to find the first non-DST one, or the first
	 * one in case there are only DST entries. Not sure which smartass came up
	 * with this idea in the first though :) */
	if (ts < tz->trans[0]) {
		uint32_t j;

		*transition_time = 0;
		j = 0;
		while (j < tz->timecnt && tz->type[j].isdst) {
			++j;
		}
		if (j == tz->timecnt) {
			j = 0;
		}
		return &(tz->type[j]);
	}

	/* In all other cases we loop through the available transtion times to find
	 * the correct entry */
	for (i = 0; i < tz->timecnt; i++) {
		if (ts < tz->trans[i]) {
			*transition_time = tz->trans[i - 1];
			return &(tz->type[tz->trans_idx[i - 1]]);
		}
	}
	*transition_time = tz->trans[tz->timecnt - 1];
	return &(tz->type[tz->trans_idx[tz->timecnt - 1]]);
}

static tlinfo* fetch_leaptime_offset(timelib_tzinfo *tz, timelib_sll ts)
{
	int i;

	if (!tz->leapcnt || !tz->leap_times) {
		return NULL;
	}

	for (i = tz->leapcnt - 1; i > 0; i--) {
		if (ts > tz->leap_times[i].trans) {
			return &(tz->leap_times[i]);
		}
	}
	return NULL;
}

int timelib_timestamp_is_in_dst(timelib_sll ts, timelib_tzinfo *tz)
{
	ttinfo *to;
	timelib_sll dummy;
	
	if ((to = fetch_timezone_offset(tz, ts, &dummy))) {
		return to->isdst;
	}
	return -1;
}

timelib_time_offset *timelib_get_time_zone_info(timelib_sll ts, timelib_tzinfo *tz)
{
	ttinfo *to;
	tlinfo *tl;
	int32_t offset = 0, leap_secs = 0;
	char *abbr;
	timelib_time_offset *tmp = timelib_time_offset_ctor();
	timelib_sll                transistion_time;

	if ((to = fetch_timezone_offset(tz, ts, &transistion_time))) {
		offset = to->offset;
		abbr = &(tz->timezone_abbr[to->abbr_idx]);
		tmp->is_dst = to->isdst;
		tmp->transistion_time = transistion_time;
	} else {
		offset = 0;
		abbr = tz->timezone_abbr;
		tmp->is_dst = 0;
		tmp->transistion_time = 0;
	}

	if ((tl = fetch_leaptime_offset(tz, ts))) {
		leap_secs = -tl->offset;
	}

	tmp->offset = offset;
	tmp->leap_secs = leap_secs;
	tmp->abbr = abbr ? strdup(abbr) : strdup("GMT");

	return tmp;
}

timelib_sll timelib_get_current_offset(timelib_time *t)
{
	timelib_time_offset *gmt_offset;
	timelib_sll retval;
			
	switch (t->zone_type) {
		case TIMELIB_ZONETYPE_ABBR:
		case TIMELIB_ZONETYPE_OFFSET:
			return (t->z + t->dst) * -60;
			
		case TIMELIB_ZONETYPE_ID:
			gmt_offset = timelib_get_time_zone_info(t->sse, t->tz_info);
			retval = gmt_offset->offset;
			timelib_time_offset_dtor(gmt_offset);
			return retval;

		default:
			return 0;
	}
}