[glib: 5/8] gtimezone: support footers in TZif files
- From: Philip Withnall <pwithnall src gnome org>
- To: commits-list gnome org
- Cc:
- Subject: [glib: 5/8] gtimezone: support footers in TZif files
- Date: Fri, 17 Jul 2020 13:55:15 +0000 (UTC)
commit 25d950b61f92f25cc9ab20d683aa4d6969f93098
Author: Paul Eggert <eggert cs ucla edu>
Date: Thu Jul 16 12:41:49 2020 -0700
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
glib/gtimezone.c | 96 ++++++++++++++++++++++++++++++++++++++++++++++++++++++--
1 file changed, 93 insertions(+), 3 deletions(-)
---
diff --git a/glib/gtimezone.c b/glib/gtimezone.c
index 80f388236e..fcf105703a 100644
--- a/glib/gtimezone.c
+++ b/glib/gtimezone.c
@@ -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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