Commit 25d950b6 authored by Paul Eggert's avatar Paul Eggert

gtimezone: support footers in TZif files

Since tzcode95f (1995), TZif files have had a trailing
TZ string, used for timestamps after the last transition.
This string is specified in Internet RFC 8536 section 3.3.
init_zone_from_iana_info has ignored this string, causing it
to mishandle timestamps past the year 2038.  With zic's new -b
slim flag, init_zone_from_iana_info would even mishandle current
timestamps.  Fix this by parsing the trailing TZ string and adding
its transitions.

Closes #2129
parent 68978631
......@@ -203,6 +203,10 @@ static GTimeZone *tz_local = NULL;
there's no point in getting carried
away. */
#ifdef G_OS_UNIX
static GTimeZone *parse_footertz (const gchar *, size_t);
#endif
/**
* g_time_zone_unref:
* @tz: a #GTimeZone
......@@ -555,7 +559,12 @@ init_zone_from_iana_info (GTimeZone *gtz,
guint8 *tz_transitions, *tz_type_index, *tz_ttinfo;
guint8 *tz_abbrs;
gsize timesize = sizeof (gint32);
const struct tzhead *header = g_bytes_get_data (zoneinfo, &size);
gconstpointer header_data = g_bytes_get_data (zoneinfo, &size);
const gchar *data = header_data;
const struct tzhead *header = header_data;
GTimeZone *footertz = NULL;
guint extra_time_count = 0, extra_type_count = 0;
gint64 last_explicit_transition_time;
g_return_if_fail (size >= sizeof (struct tzhead) &&
memcmp (header, "TZif", 4) == 0);
......@@ -576,6 +585,30 @@ init_zone_from_iana_info (GTimeZone *gtz,
time_count = guint32_from_be(header->tzh_timecnt);
type_count = guint32_from_be(header->tzh_typecnt);
if (header->tzh_version >= '2')
{
const gchar *footer = (((const gchar *) (header + 1))
+ guint32_from_be(header->tzh_ttisgmtcnt)
+ guint32_from_be(header->tzh_ttisstdcnt)
+ 12 * guint32_from_be(header->tzh_leapcnt)
+ 9 * time_count
+ 6 * type_count
+ guint32_from_be(header->tzh_charcnt));
const gchar *footerlast;
size_t footerlen;
g_return_if_fail (footer <= data + size - 2 && footer[0] == '\n');
footerlast = memchr (footer + 1, '\n', data + size - (footer + 1));
g_return_if_fail (footerlast);
footerlen = footerlast + 1 - footer;
if (footerlen != 2)
{
footertz = parse_footertz (footer, footerlen);
g_return_if_fail (footertz);
extra_type_count = footertz->t_info->len;
extra_time_count = footertz->transitions->len;
}
}
tz_transitions = ((guint8 *) (header) + sizeof (*header));
tz_type_index = tz_transitions + timesize * time_count;
tz_ttinfo = tz_type_index + time_count;
......@@ -583,9 +616,9 @@ init_zone_from_iana_info (GTimeZone *gtz,
gtz->name = g_steal_pointer (&identifier);
gtz->t_info = g_array_sized_new (FALSE, TRUE, sizeof (TransitionInfo),
type_count);
type_count + extra_type_count);
gtz->transitions = g_array_sized_new (FALSE, TRUE, sizeof (Transition),
time_count);
time_count + extra_time_count);
for (index = 0; index < type_count; index++)
{
......@@ -604,11 +637,46 @@ init_zone_from_iana_info (GTimeZone *gtz,
trans.time = gint64_from_be (((gint64_be*)tz_transitions)[index]);
else
trans.time = gint32_from_be (((gint32_be*)tz_transitions)[index]);
last_explicit_transition_time = trans.time;
trans.info_index = tz_type_index[index];
g_assert (trans.info_index >= 0);
g_assert ((guint) trans.info_index < gtz->t_info->len);
g_array_append_val (gtz->transitions, trans);
}
if (footertz)
{
/* Append footer time types. Don't bother to coalesce
duplicates with existing time types. */
for (index = 0; index < extra_type_count; index++)
{
TransitionInfo t_info;
TransitionInfo *footer_t_info
= &g_array_index (footertz->t_info, TransitionInfo, index);
t_info.gmt_offset = footer_t_info->gmt_offset;
t_info.is_dst = footer_t_info->is_dst;
t_info.abbrev = g_steal_pointer (&footer_t_info->abbrev);
g_array_append_val (gtz->t_info, t_info);
}
/* Append footer transitions that follow the last explicit
transition. */
for (index = 0; index < extra_time_count; index++)
{
Transition *footer_transition
= &g_array_index (footertz->transitions, Transition, index);
if (time_count <= 0
|| last_explicit_transition_time < footer_transition->time)
{
Transition trans;
trans.time = footer_transition->time;
trans.info_index = type_count + footer_transition->info_index;
g_array_append_val (gtz->transitions, trans);
}
}
g_time_zone_unref (footertz);
}
}
#elif defined (G_OS_WIN32)
......@@ -1504,6 +1572,28 @@ rules_from_identifier (const gchar *identifier,
return create_ruleset_from_rule (rules, &tzr);
}
#ifdef G_OS_UNIX
static GTimeZone *
parse_footertz (const gchar *footer, size_t footerlen)
{
gchar *tzstring = g_strndup (footer + 1, footerlen - 2);
GTimeZone *footertz = NULL;
gchar *ident;
TimeZoneRule *rules;
guint rules_num = rules_from_identifier (tzstring, &ident, &rules);
g_free (ident);
g_free (tzstring);
if (rules_num > 1)
{
footertz = g_slice_new0 (GTimeZone);
init_zone_from_rules (footertz, rules, rules_num, NULL);
footertz->ref_count++;
}
g_free (rules);
return footertz;
}
#endif
/* Construction {{{1 */
/**
* g_time_zone_new:
......
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