parse_tz.c

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/*
 * The MIT License (MIT)
 *
 * Copyright (c) 2015-2019 Derick Rethans
 * Copyright (c) 2018 MongoDB, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
 
#include "timelib.h"
#include "timelib_private.h"
 
#define TIMELIB_SUPPORTS_V2DATA
#define TIMELIB_SUPPORT_SLIM_FILE
#include "timezonedb.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
 
#if (defined(__BYTE_ORDER) && defined(__BIG_ENDIAN))
# if __BYTE_ORDER == __BIG_ENDIAN
#  define WORDS_BIGENDIAN
# endif
#endif
 
#if defined(__s390__)
# if __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
#  define WORDS_BIGENDIAN
# else
#  undef WORDS_BIGENDIAN
# endif
#endif
 
#ifdef WORDS_BIGENDIAN
static inline uint32_t timelib_conv_int_unsigned(uint32_t value)
{
    return value;
}
 
static inline uint64_t timelib_conv_int64_unsigned(uint64_t value)
{
    return value;
}
#else
static inline uint32_t timelib_conv_int_unsigned(uint32_t value)
{
    return
        ((value & 0x000000ff) << 24) +
        ((value & 0x0000ff00) <<  8) +
        ((value & 0x00ff0000) >>  8) +
        ((value & 0xff000000) >> 24);
}
 
static inline uint64_t timelib_conv_int64_unsigned(uint64_t value)
{
    return
        ((value & 0x00000000000000ff) << 56) +
        ((value & 0x000000000000ff00) << 40) +
        ((value & 0x0000000000ff0000) << 24) +
        ((value & 0x00000000ff000000) <<  8) +
        ((value & 0x000000ff00000000) >>  8) +
        ((value & 0x0000ff0000000000) >> 24) +
        ((value & 0x00ff000000000000) >> 40) +
        ((value & 0xff00000000000000) >> 56);
}
#endif
 
#define timelib_conv_int_signed(value) ((int32_t) timelib_conv_int_unsigned((int32_t) value))
#define timelib_conv_int64_signed(value) ((int64_t) timelib_conv_int64_unsigned((int64_t) value))
 
static int read_php_preamble(const unsigned char **tzf, timelib_tzinfo *tz)
{
    uint32_t version;
 
    /* read ID */
    version = (*tzf)[3] - '0';
    *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 rest of preamble */
    *tzf += 13;
 
    return version;
}
 
static int read_tzif_preamble(const unsigned char **tzf, timelib_tzinfo *tz)
{
    uint32_t version;
 
    /* read ID */
    switch ((*tzf)[4]) {
        case '\0':
            version = 0;
            break;
        case '2':
            version = 2;
            break;
        case '3':
            version = 3;
            break;
        case '4':
            version = 4;
            break;
        default:
            return -1;
    }
    *tzf += 5;
 
    /* set BC flag and country code to default */
    tz->bc = 0;
    tz->location.country_code[0] = '?';
    tz->location.country_code[1] = '?';
    tz->location.country_code[2] = '\0';
 
    /* skip rest of preamble */
    *tzf += 15;
 
    return version;
}
 
static int read_preamble(const unsigned char **tzf, timelib_tzinfo *tz, unsigned int *type)
{
    /* read marker (TZif) or (PHP) */
    if (memcmp(*tzf, "PHP", 3) == 0) {
        *type = TIMELIB_TZINFO_PHP;
        return read_php_preamble(tzf, tz);
    } else if (memcmp(*tzf, "TZif", 4) == 0) {
        *type = TIMELIB_TZINFO_ZONEINFO;
        return read_tzif_preamble(tzf, tz);
    } else {
        return -1;
    }
}
 
static void read_32bit_header(const unsigned char **tzf, timelib_tzinfo *tz)
{
    uint32_t buffer[6];
 
    memcpy(&buffer, *tzf, sizeof(buffer));
    tz->_bit32.ttisgmtcnt = timelib_conv_int_unsigned(buffer[0]);
    tz->_bit32.ttisstdcnt = timelib_conv_int_unsigned(buffer[1]);
    tz->_bit32.leapcnt    = timelib_conv_int_unsigned(buffer[2]);
    tz->_bit32.timecnt    = timelib_conv_int_unsigned(buffer[3]);
    tz->_bit32.typecnt    = timelib_conv_int_unsigned(buffer[4]);
    tz->_bit32.charcnt    = timelib_conv_int_unsigned(buffer[5]);
 
    *tzf += sizeof(buffer);
}
 
static int detect_slim_file(timelib_tzinfo *tz)
{
    if (
        (tz->_bit32.ttisgmtcnt == 0) &&
        (tz->_bit32.ttisstdcnt == 0) &&
        (tz->_bit32.leapcnt    == 0) &&
        (tz->_bit32.timecnt    == 0) &&
        (tz->_bit32.typecnt    == 1) &&
        (tz->_bit32.charcnt    == 1)
    ) {
        return 1;
    }
 
    return 0;
}
 
static int read_64bit_transitions(const unsigned char **tzf, timelib_tzinfo *tz)
{
    int64_t *buffer = NULL;
    uint32_t i;
    unsigned char *cbuffer = NULL;
 
    if (tz->bit64.timecnt) {
        buffer = (int64_t*) timelib_malloc(tz->bit64.timecnt * sizeof(int64_t));
        if (!buffer) {
            return TIMELIB_ERROR_CANNOT_ALLOCATE;
        }
        memcpy(buffer, *tzf, sizeof(int64_t) * tz->bit64.timecnt);
        *tzf += (sizeof(int64_t) * tz->bit64.timecnt);
        for (i = 0; i < tz->bit64.timecnt; i++) {
            buffer[i] = timelib_conv_int64_signed(buffer[i]);
            /* Sanity check to see whether TS is just increasing */
            if (i > 0 && !(buffer[i] > buffer[i - 1])) {
                return TIMELIB_ERROR_CORRUPT_TRANSITIONS_DONT_INCREASE;
            }
        }
 
        cbuffer = (unsigned char*) timelib_malloc(tz->bit64.timecnt * sizeof(unsigned char));
        if (!cbuffer) {
            timelib_free(buffer);
            return TIMELIB_ERROR_CANNOT_ALLOCATE;
        }
        memcpy(cbuffer, *tzf, sizeof(unsigned char) * tz->bit64.timecnt);
        *tzf += sizeof(unsigned char) * tz->bit64.timecnt;
    }
 
    tz->trans = buffer;
    tz->trans_idx = cbuffer;
 
    return 0;
}
 
static void skip_32bit_transitions(const unsigned char **tzf, timelib_tzinfo *tz)
{
    if (tz->_bit32.timecnt) {
        *tzf += (sizeof(int32_t) * tz->_bit32.timecnt);
        *tzf += sizeof(unsigned char) * tz->_bit32.timecnt;
    }
}
 
static int read_64bit_types(const unsigned char **tzf, timelib_tzinfo *tz)
{
    unsigned char *buffer;
    int32_t *leap_buffer;
    unsigned int i, j;
 
    /* Offset Types */
    buffer = (unsigned char*) timelib_malloc(tz->bit64.typecnt * sizeof(unsigned char) * 6);
    if (!buffer) {
        return TIMELIB_ERROR_CANNOT_ALLOCATE;
    }
    memcpy(buffer, *tzf, sizeof(unsigned char) * 6 * tz->bit64.typecnt);
    *tzf += sizeof(unsigned char) * 6 * tz->bit64.typecnt;
 
    // We add two extra to have space for potential new ttinfo entries due to new types defined in the
    // POSIX string
    tz->type = (ttinfo*) timelib_calloc(1, (tz->bit64.typecnt + 2) * sizeof(ttinfo));
    if (!tz->type) {
        timelib_free(buffer);
        return TIMELIB_ERROR_CANNOT_ALLOCATE;
    }
 
    for (i = 0; i < tz->bit64.typecnt; i++) {
        j = i * 6;
        tz->type[i].offset = 0;
        tz->type[i].offset += (int32_t) (((uint32_t) buffer[j]) << 24) + (buffer[j + 1] << 16) + (buffer[j + 2] << 8) + tz->type[i].offset + buffer[j + 3];
        tz->type[i].isdst = buffer[j + 4];
        tz->type[i].abbr_idx = buffer[j + 5];
    }
    timelib_free(buffer);
 
    /* Abbreviations */
    tz->timezone_abbr = (char*) timelib_malloc(tz->bit64.charcnt);
    if (!tz->timezone_abbr) {
        return TIMELIB_ERROR_CORRUPT_NO_ABBREVIATION;
    }
    memcpy(tz->timezone_abbr, *tzf, sizeof(char) * tz->bit64.charcnt);
    *tzf += sizeof(char) * tz->bit64.charcnt;
 
    /* Leap seconds (only use in 'right/') format */
    if (tz->bit64.leapcnt) {
        leap_buffer = (int32_t *) timelib_malloc(tz->bit64.leapcnt * (sizeof(int64_t) + sizeof(int32_t)));
        if (!leap_buffer) {
            return TIMELIB_ERROR_CANNOT_ALLOCATE;
        }
        memcpy(leap_buffer, *tzf, tz->bit64.leapcnt * (sizeof(int64_t) + sizeof(int32_t)));
        *tzf += tz->bit64.leapcnt * (sizeof(int64_t) + sizeof(int32_t));
 
        tz->leap_times = (tlinfo*) timelib_malloc(tz->bit64.leapcnt * sizeof(tlinfo));
        if (!tz->leap_times) {
            timelib_free(leap_buffer);
            return TIMELIB_ERROR_CANNOT_ALLOCATE;
        }
        for (i = 0; i < tz->bit64.leapcnt; i++) {
            tz->leap_times[i].trans = timelib_conv_int64_signed(leap_buffer[i * 3 + 1] * 4294967296 + leap_buffer[i * 3]);
            tz->leap_times[i].offset = timelib_conv_int_signed(leap_buffer[i * 3 + 2]);
        }
        timelib_free(leap_buffer);
    }
 
    /* Standard/Wall Indicators (unused) */
    if (tz->bit64.ttisstdcnt) {
        buffer = (unsigned char*) timelib_malloc(tz->bit64.ttisstdcnt * sizeof(unsigned char));
        if (!buffer) {
            return TIMELIB_ERROR_CANNOT_ALLOCATE;
        }
        memcpy(buffer, *tzf, sizeof(unsigned char) * tz->bit64.ttisstdcnt);
        *tzf += sizeof(unsigned char) * tz->bit64.ttisstdcnt;
 
        for (i = 0; i < tz->bit64.ttisstdcnt; i++) {
            tz->type[i].isstdcnt = buffer[i];
        }
        timelib_free(buffer);
    }
 
    /* UT/Local Time Indicators (unused) */
    if (tz->bit64.ttisgmtcnt) {
        buffer = (unsigned char*) timelib_malloc(tz->bit64.ttisgmtcnt * sizeof(unsigned char));
        if (!buffer) {
            return TIMELIB_ERROR_CANNOT_ALLOCATE;
        }
        memcpy(buffer, *tzf, sizeof(unsigned char) * tz->bit64.ttisgmtcnt);
        *tzf += sizeof(unsigned char) * tz->bit64.ttisgmtcnt;
 
        for (i = 0; i < tz->bit64.ttisgmtcnt; i++) {
            tz->type[i].isgmtcnt = buffer[i];
        }
        timelib_free(buffer);
    }
 
    return 0;
}
 
static void skip_32bit_types(const unsigned char **tzf, timelib_tzinfo *tz)
{
    /* Offset Types */
    *tzf += sizeof(unsigned char) * 6 * tz->_bit32.typecnt;
 
    /* Abbreviations */
    *tzf += sizeof(char) * tz->_bit32.charcnt;
 
    /* Leap seconds (only use in 'right/') format */
    if (tz->_bit32.leapcnt) {
        *tzf += sizeof(int32_t) * tz->_bit32.leapcnt * 2;
    }
 
    /* Standard/Wall Indicators (unused) */
    if (tz->_bit32.ttisstdcnt) {
        *tzf += sizeof(unsigned char) * tz->_bit32.ttisstdcnt;
    }
 
    /* UT/Local Time Indicators (unused) */
    if (tz->_bit32.ttisgmtcnt) {
        *tzf += sizeof(unsigned char) * tz->_bit32.ttisgmtcnt;
    }
}
 
static void read_posix_string(const unsigned char **tzf, timelib_tzinfo *tz)
{
    const unsigned char *begin;
 
    // POSIX string is delimited by \n
    (*tzf)++;
    begin = *tzf;
 
    while (*tzf[0] != '\n') {
        (*tzf)++;
    }
 
    tz->posix_string = timelib_calloc(1, *tzf - begin + 1);
    memcpy(tz->posix_string, begin, *tzf - begin);
 
    // skip over closing \n
    (*tzf)++;
}
 
static signed int find_ttinfo_index(timelib_tzinfo *tz, int32_t offset, int isdst, char *abbr)
{
    uint64_t i;
 
    for (i = 0; i < tz->bit64.typecnt; i++) {
        if (
            (offset == tz->type[i].offset) &&
            (isdst == tz->type[i].isdst) &&
            (strcmp(abbr, &tz->timezone_abbr[tz->type[i].abbr_idx]) == 0)
        ) {
            return i;
        }
    }
 
    return TIMELIB_UNSET;
}
 
static unsigned int add_abbr(timelib_tzinfo *tz, char *abbr)
{
    size_t old_length = tz->bit64.charcnt;
    size_t new_length = old_length + strlen(abbr) + 1;
    tz->timezone_abbr = (char*) timelib_realloc(tz->timezone_abbr, new_length);
    memcpy(tz->timezone_abbr + old_length, abbr, strlen(abbr));
    tz->bit64.charcnt = new_length;
    tz->timezone_abbr[new_length - 1] = '\0';
 
    return old_length;
}
 
static signed int add_new_ttinfo_index(timelib_tzinfo *tz, int32_t offset, int isdst, char *abbr)
{
    tz->type[tz->bit64.typecnt].offset = offset;
    tz->type[tz->bit64.typecnt].isdst = isdst;
    tz->type[tz->bit64.typecnt].abbr_idx = add_abbr(tz, abbr);
    tz->type[tz->bit64.typecnt].isstdcnt = 0;
    tz->type[tz->bit64.typecnt].isgmtcnt = 0;
 
    ++tz->bit64.typecnt;
 
    return tz->bit64.typecnt - 1;
}
 
static int integrate_posix_string(timelib_tzinfo *tz)
{
    tz->posix_info = timelib_parse_posix_str(tz->posix_string);
    if (!tz->posix_info) {
        return 0;
    }
 
    tz->posix_info->type_index_std_type = find_ttinfo_index(tz, tz->posix_info->std_offset, 0, tz->posix_info->std);
    if (tz->posix_info->type_index_std_type == TIMELIB_UNSET) {
        tz->posix_info->type_index_std_type = add_new_ttinfo_index(tz, tz->posix_info->std_offset, 0, tz->posix_info->std);
        return 1;
    }
 
    /* If there is no DST set for this zone, return */
    if (!tz->posix_info->dst) {
        return 1;
    }
 
    tz->posix_info->type_index_dst_type = find_ttinfo_index(tz, tz->posix_info->dst_offset, 1, tz->posix_info->dst);
    if (tz->posix_info->type_index_dst_type == TIMELIB_UNSET) {
        tz->posix_info->type_index_dst_type = add_new_ttinfo_index(tz, tz->posix_info->dst_offset, 1, tz->posix_info->dst);
        return 1;
    }
 
    return 1;
}
 
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_unsigned(buffer[0]);
    tz->location.latitude = (tz->location.latitude / 100000) - 90;
    tz->location.longitude = timelib_conv_int_unsigned(buffer[1]);
    tz->location.longitude = (tz->location.longitude / 100000) - 180;
    comments_len = timelib_conv_int_unsigned(buffer[2]);
    *tzf += sizeof(buffer);
 
    tz->location.comments = timelib_malloc(comments_len + 1);
    memcpy(tz->location.comments, *tzf, comments_len);
    tz->location.comments[comments_len] = '\0';
    *tzf += comments_len;
}
 
static void set_default_location_and_comments(const unsigned char **tzf, timelib_tzinfo *tz)
{
    tz->location.latitude = 0;
    tz->location.longitude = 0;
    tz->location.comments = timelib_malloc(2);
    tz->location.comments[0] = '?';
    tz->location.comments[1] = '\0';
}
 
static char *format_ut_time(timelib_sll ts, timelib_tzinfo *tz)
{
    char *tmp = timelib_calloc(1, 64);
    timelib_time *t = timelib_time_ctor();
 
    timelib_unixtime2gmt(t, ts);
    snprintf(
        tmp, 64,
        "%04lld-%02lld-%02lld %02lld:%02lld:%02lld UT",
        t->y, t->m, t->d,
        t->h, t->i, t->s
    );
 
    timelib_time_dtor(t);
    return tmp;
}
 
static char *format_offset_type(timelib_tzinfo *tz, int i)
{
    char *tmp = timelib_calloc(1, 64);
 
    snprintf(
        tmp, 64,
        "%3d [%6ld %1d %3d '%s' (%d,%d)]",
        i,
        (long int) tz->type[i].offset,
        tz->type[i].isdst,
        tz->type[i].abbr_idx,
        &tz->timezone_abbr[tz->type[i].abbr_idx],
        tz->type[i].isstdcnt,
        tz->type[i].isgmtcnt
    );
 
    return tmp;
}
 
void timelib_dump_tzinfo(timelib_tzinfo *tz)
{
    uint32_t  i;
    char     *date_str, *trans_str;
 
    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 ? "no" : "yes");
    printf("Slim File:         %s\n",  detect_slim_file(tz) ? "yes" : "no");
 
    printf("\n64-bit:\n");
    printf("UTC/Local count:   " TIMELIB_ULONG_FMT "\n", (timelib_ulong) tz->bit64.ttisgmtcnt);
    printf("Std/Wall count:    " TIMELIB_ULONG_FMT "\n", (timelib_ulong) tz->bit64.ttisstdcnt);
    printf("Leap.sec. count:   " TIMELIB_ULONG_FMT "\n", (timelib_ulong) tz->bit64.leapcnt);
    printf("Trans. count:      " TIMELIB_ULONG_FMT "\n", (timelib_ulong) tz->bit64.timecnt);
    printf("Local types count: " TIMELIB_ULONG_FMT "\n", (timelib_ulong) tz->bit64.typecnt);
    printf("Zone Abbr. count:  " TIMELIB_ULONG_FMT "\n", (timelib_ulong) tz->bit64.charcnt);
 
    trans_str = format_offset_type(tz, 0);
    printf("%22s (%20s) = %s\n", "", "", trans_str);
    timelib_free(trans_str);
 
    for (i = 0; i < tz->bit64.timecnt; i++) {
        date_str = format_ut_time(tz->trans[i], tz);
        trans_str = format_offset_type(tz, tz->trans_idx[i]);
        printf(
            "%s (%20" PRId64 ") = %s\n",
            date_str,
            tz->trans[i],
            trans_str
        );
        timelib_free(date_str);
        timelib_free(trans_str);
    }
    for (i = 0; i < tz->bit64.leapcnt; i++) {
        date_str = format_ut_time(tz->trans[i], tz);
        printf (
            "%s (%20ld) = %d\n",
            date_str,
            (long) tz->leap_times[i].trans,
            tz->leap_times[i].offset
        );
        timelib_free(date_str);
    }
 
    if (!tz->posix_string) {
        printf("\n%43sNo POSIX string\n", "");
        return;
    }
 
    if (strcmp("", tz->posix_string) == 0) {
        printf("\n%43sEmpty POSIX string\n", "");
        return;
    }
 
    printf("\n%43sPOSIX string: %s\n", "", tz->posix_string);
    if (tz->posix_info && tz->posix_info->std) {
        trans_str = format_offset_type(tz, tz->posix_info->type_index_std_type);
        printf("%43sstd: %s\n", "", trans_str);
        timelib_free(trans_str);
 
        if (tz->posix_info->dst) {
            trans_str = format_offset_type(tz, tz->posix_info->type_index_dst_type);
            printf("%43sdst: %s\n", "", trans_str);
            timelib_free(trans_str);
        }
    }
}
 
static int seek_to_tz_position(const unsigned char **tzf, const char *timezone, const timelib_tzdb *tzdb)
{
    int left = 0, right = tzdb->index_size - 1;
 
    if (tzdb->index_size == 0) {
        return 0;
    }
 
    do {
        int mid = ((unsigned)left + right) >> 1;
        int cmp = timelib_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]);
            return 1;
        }
 
    } while (left <= right);
 
    return 0;
}
 
const timelib_tzdb *timelib_builtin_db(void)
{
    return &timezonedb_builtin;
}
 
const timelib_tzdb_index_entry *timelib_timezone_identifiers_list(const timelib_tzdb *tzdb, int *count)
{
    *count = tzdb->index_size;
    return tzdb->index;
}
 
int timelib_timezone_id_is_valid(const char *timezone, const timelib_tzdb *tzdb)
{
    const unsigned char *tzf;
    return (seek_to_tz_position(&tzf, timezone, tzdb));
}
 
static int skip_64bit_preamble(const unsigned char **tzf, timelib_tzinfo *tz)
{
    if (memcmp(*tzf, "TZif2", 5) == 0) {
        *tzf += 20;
        return 1;
    } else if (memcmp(*tzf, "TZif3", 5) == 0) {
        *tzf += 20;
        return 1;
    } else if (memcmp(*tzf, "TZif4", 5) == 0) {
        *tzf += 20;
        return 1;
    } else {
        return 0;
    }
}
 
static void read_64bit_header(const unsigned char **tzf, timelib_tzinfo *tz)
{
    uint32_t buffer[6];
 
    memcpy(&buffer, *tzf, sizeof(buffer));
    tz->bit64.ttisgmtcnt = timelib_conv_int_unsigned(buffer[0]);
    tz->bit64.ttisstdcnt = timelib_conv_int_unsigned(buffer[1]);
    tz->bit64.leapcnt    = timelib_conv_int_unsigned(buffer[2]);
    tz->bit64.timecnt    = timelib_conv_int_unsigned(buffer[3]);
    tz->bit64.typecnt    = timelib_conv_int_unsigned(buffer[4]);
    tz->bit64.charcnt    = timelib_conv_int_unsigned(buffer[5]);
    *tzf += sizeof(buffer);
}
 
static timelib_tzinfo* timelib_tzinfo_ctor(const char *name)
{
    timelib_tzinfo *t;
    t = timelib_calloc(1, sizeof(timelib_tzinfo));
    t->name = timelib_strdup(name);
 
    return t;
}
 
timelib_tzinfo *timelib_parse_tzfile(const char *timezone, const timelib_tzdb *tzdb, int *error_code)
{
    const unsigned char *tzf;
    timelib_tzinfo *tmp;
    int version;
    int transitions_result, types_result;
    unsigned int type = TIMELIB_TZINFO_ZONEINFO; /* TIMELIB_TZINFO_PHP or TIMELIB_TZINFO_ZONEINFO */
 
    *error_code = TIMELIB_ERROR_NO_ERROR;
 
    if (seek_to_tz_position(&tzf, timezone, tzdb)) {
        tmp = timelib_tzinfo_ctor(timezone);
 
        version = read_preamble(&tzf, tmp, &type);
        if (version < 2 || version > 4) {
            *error_code = TIMELIB_ERROR_UNSUPPORTED_VERSION;
            timelib_tzinfo_dtor(tmp);
            return NULL;
        }
//printf("- timezone: %s, version: %0d\n", timezone, version);
 
        read_32bit_header(&tzf, tmp);
        skip_32bit_transitions(&tzf, tmp);
        skip_32bit_types(&tzf, tmp);
 
        if (!skip_64bit_preamble(&tzf, tmp)) {
            /* 64 bit preamble is not in place */
            *error_code = TIMELIB_ERROR_CORRUPT_NO_64BIT_PREAMBLE;
            timelib_tzinfo_dtor(tmp);
            return NULL;
        }
        read_64bit_header(&tzf, tmp);
        if ((transitions_result = read_64bit_transitions(&tzf, tmp)) != 0) {
            /* Corrupt file as transitions do not increase */
            *error_code = transitions_result;
            timelib_tzinfo_dtor(tmp);
            return NULL;
        }
        if ((types_result = read_64bit_types(&tzf, tmp)) != 0) {
            *error_code = types_result;
            timelib_tzinfo_dtor(tmp);
            return NULL;
        }
 
        read_posix_string(&tzf, tmp);
        if (strcmp("", tmp->posix_string) == 0) {
            *error_code = TIMELIB_ERROR_EMPTY_POSIX_STRING;
        } else if (!integrate_posix_string(tmp)) {
            *error_code = TIMELIB_ERROR_CORRUPT_POSIX_STRING;
            timelib_tzinfo_dtor(tmp);
            return NULL;
        }
 
        if (type == TIMELIB_TZINFO_PHP) {
            read_location(&tzf, tmp);
        } else {
            set_default_location_and_comments(&tzf, tmp);
        }
    } else {
        *error_code = TIMELIB_ERROR_NO_SUCH_TIMEZONE;
        tmp = NULL;
    }
 
    return tmp;
}
 
void timelib_tzinfo_dtor(timelib_tzinfo *tz)
{
    TIMELIB_TIME_FREE(tz->name);
    TIMELIB_TIME_FREE(tz->trans);
    TIMELIB_TIME_FREE(tz->trans_idx);
    TIMELIB_TIME_FREE(tz->type);
    TIMELIB_TIME_FREE(tz->timezone_abbr);
    TIMELIB_TIME_FREE(tz->leap_times);
    TIMELIB_TIME_FREE(tz->location.comments);
    TIMELIB_TIME_FREE(tz->posix_string);
    if (tz->posix_info) {
        timelib_posix_str_dtor(tz->posix_info);
    }
    TIMELIB_TIME_FREE(tz);
    tz = NULL;
}
 
timelib_tzinfo *timelib_tzinfo_clone(timelib_tzinfo *tz)
{
    timelib_tzinfo *tmp = timelib_tzinfo_ctor(tz->name);
    tmp->_bit32.ttisgmtcnt = tz->_bit32.ttisgmtcnt;
    tmp->_bit32.ttisstdcnt = tz->_bit32.ttisstdcnt;
    tmp->_bit32.leapcnt = tz->_bit32.leapcnt;
    tmp->_bit32.timecnt = tz->_bit32.timecnt;
    tmp->_bit32.typecnt = tz->_bit32.typecnt;
    tmp->_bit32.charcnt = tz->_bit32.charcnt;
    tmp->bit64.ttisgmtcnt = tz->bit64.ttisgmtcnt;
    tmp->bit64.ttisstdcnt = tz->bit64.ttisstdcnt;
    tmp->bit64.leapcnt = tz->bit64.leapcnt;
    tmp->bit64.timecnt = tz->bit64.timecnt;
    tmp->bit64.typecnt = tz->bit64.typecnt;
    tmp->bit64.charcnt = tz->bit64.charcnt;
 
    if (tz->bit64.timecnt) {
        tmp->trans = (int64_t *) timelib_malloc(tz->bit64.timecnt * sizeof(int64_t));
        tmp->trans_idx = (unsigned char*) timelib_malloc(tz->bit64.timecnt * sizeof(unsigned char));
        memcpy(tmp->trans, tz->trans, tz->bit64.timecnt * sizeof(int64_t));
        memcpy(tmp->trans_idx, tz->trans_idx, tz->bit64.timecnt * sizeof(unsigned char));
    }
 
    tmp->type = (ttinfo*) timelib_malloc(tz->bit64.typecnt * sizeof(ttinfo));
    memcpy(tmp->type, tz->type, tz->bit64.typecnt * sizeof(ttinfo));
 
    tmp->timezone_abbr = (char*) timelib_malloc(tz->bit64.charcnt);
    memcpy(tmp->timezone_abbr, tz->timezone_abbr, tz->bit64.charcnt);
 
    if (tz->bit64.leapcnt) {
        tmp->leap_times = (tlinfo*) timelib_malloc(tz->bit64.leapcnt * sizeof(tlinfo));
        memcpy(tmp->leap_times, tz->leap_times, tz->bit64.leapcnt * sizeof(tlinfo));
    }
 
    if (tz->posix_string) {
        tmp->posix_string = timelib_strdup(tz->posix_string);
    }
 
    return tmp;
}

ttinfo* timelib_fetch_timezone_offset(timelib_tzinfo *tz, timelib_sll ts, timelib_sll *transition_time)
{
    uint32_t left, right;
 
    /* RFC 8536: If there are no transitions, local time for all timestamps is specified
     * by the TZ string in the footer if present and nonempty; otherwise, it is specified
     * by time type 0.
     *
     * timelib: If there is also no time type 0, return NULL.
     */
    if (!tz->bit64.timecnt || !tz->trans) {
        if (tz->posix_info) {
            *transition_time = INT64_MIN;
            return timelib_fetch_posix_timezone_offset(tz, ts, NULL);
        }
 
        if (tz->bit64.typecnt == 1) {
            *transition_time = INT64_MIN;
            return &(tz->type[0]);
        }
        return NULL;
    }
 
    /* RFC 8536: Local time for timestamps before the first transition is specified by
     * the first time type (time type 0). */
    if (ts < tz->trans[0]) {
        *transition_time = INT64_MIN;
        return &(tz->type[0]);
    }
 
    /* RFC 8536: Local time for timestamps on or after the last transition is specified
     * by the TZ string in the footer (Section 3.3) if present and nonempty; otherwise,
     * it is unspecified.
     *
     * timelib: For 'unspecified', timelib assumes the last transition
     */
    if (ts >= tz->trans[tz->bit64.timecnt - 1]) {
        if (tz->posix_info) {
            return timelib_fetch_posix_timezone_offset(tz, ts, transition_time);
        }
 
        *transition_time = tz->trans[tz->bit64.timecnt - 1];
        return &(tz->type[tz->trans_idx[tz->bit64.timecnt - 1]]);
    }
 
    /* RFC 8536: The type corresponding to a transition time specifies local time for
     * timestamps starting at the given transition time and continuing up to, but not
     * including, the next transition time. */
    left = 0;
    right = tz->bit64.timecnt - 1;
 
    while (right - left > 1) {
        uint32_t mid = (left + right) >> 1;
 
        if (ts < tz->trans[mid]) {
            right = mid;
        } else {
            left = mid;
        }
    }
    *transition_time = tz->trans[left];
    return &(tz->type[tz->trans_idx[left]]);
}
 
static tlinfo* fetch_leaptime_offset(timelib_tzinfo *tz, timelib_sll ts)
{
    int i;
 
    if (!tz->bit64.leapcnt || !tz->leap_times) {
        return NULL;
    }
 
    for (i = tz->bit64.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 = timelib_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                transition_time;
 
    if ((to = timelib_fetch_timezone_offset(tz, ts, &transition_time))) {
        offset = to->offset;
        abbr = &(tz->timezone_abbr[to->abbr_idx]);
        tmp->is_dst = to->isdst;
        tmp->transition_time = transition_time;
    } else {
        offset = 0;
        abbr = tz->timezone_abbr;
        tmp->is_dst = 0;
        tmp->transition_time = 0;
    }
 
    if ((tl = fetch_leaptime_offset(tz, ts))) {
        leap_secs = -tl->offset;
    }
 
    tmp->offset = offset;
    tmp->leap_secs = leap_secs;
    tmp->abbr = abbr ? timelib_strdup(abbr) : timelib_strdup("GMT");
 
    return tmp;
}
 
int timelib_get_time_zone_offset_info(timelib_sll ts, timelib_tzinfo *tz, int32_t* offset, timelib_sll* transition_time, unsigned int* is_dst)
{
    ttinfo *to;
    timelib_sll tmp_transition_time;
 
    if (tz == NULL) {
        return 0;
    }
 
    if ((to = timelib_fetch_timezone_offset(tz, ts, &tmp_transition_time))) {
        if (offset) {
            *offset = to->offset;
        }
        if (is_dst) {
            *is_dst = to->isdst;
        }
        if (transition_time) {
            *transition_time = tmp_transition_time;
        }
        return 1;
    }
    return 0;
}
 
timelib_sll timelib_get_current_offset(timelib_time *t)
{
    switch (t->zone_type) {
        case TIMELIB_ZONETYPE_ABBR:
        case TIMELIB_ZONETYPE_OFFSET:
            return t->z + (t->dst * 3600);
 
        case TIMELIB_ZONETYPE_ID: {
            int32_t      offset = 0;
            timelib_get_time_zone_offset_info(t->sse, t->tz_info, &offset, NULL, NULL);
            return offset;
        }
 
        default:
            return 0;
    }
}
 
int timelib_same_timezone(timelib_time *one, timelib_time *two)
{
    if (one->zone_type != two->zone_type) {
        return 0;
    }
 
    if (one->zone_type == TIMELIB_ZONETYPE_ABBR || one->zone_type == TIMELIB_ZONETYPE_OFFSET) {
        if ((one->z + (one->dst * 3600)) == (two->z + (two->dst * 3600))) {
            return 1;
        }
        return 0;
    }
 
    if (one->zone_type == TIMELIB_ZONETYPE_ID && strcmp(one->tz_info->name, two->tz_info->name) == 0) {
        return 1;
    }
 
    return 0;
}