termux-packages/packages/glib/glib-gtimezone.patch

--- ./glib/gtimezone.c.orig	2021-12-11 16:52:41.154480293 +0530
+++ ./glib/gtimezone.c	2021-12-11 16:53:59.829643030 +0530
@@ -46,6 +46,10 @@
 #include <wchar.h>
 #endif
 
+#ifdef __ANDROID__
+#include <sys/system_properties.h>
+#endif
+
 /**
  * SECTION:timezone
  * @title: GTimeZone
@@ -509,6 +513,135 @@
   return resolved_identifier;
 }
 
+/* Android uses a 'persist.sys.timezone' system property for the
+ * current timezone instead of a /etc/localtime file:
+ * https://android.googlesource.com/platform/ndk/+/android-2.2_r1/docs/system/libc/OVERVIEW.TXT#67
+ *
+ * There are no files under /usr/share/zoneinfo - instead a single
+ * /system/usr/share/zoneinfo/tzdata file is used which contains all
+ * files compiled together with the following tool:
+ * https://android.googlesource.com/platform/system/timezone/+/master/zone_compactor/main/java/ZoneCompactor.java
+ */
+static GBytes *
+zone_info_android (const gchar  *identifier,
+                   gchar       **out_identifier)
+{
+  char sys_timezone[PROP_VALUE_MAX];
+  GMappedFile *file;
+  gchar *tzdata;
+  gsize tzdata_length;
+  const gsize index_entry_size = 52;
+  gint32 header_index_offset, header_data_offset;
+  gint32 entry_count, current_index;
+  char* entry_name;
+  gint32 entry_offset, entry_length;
+  guint32 entry_name_start, entry_name_end;
+  guint32 zoneinfo_start, zoneinfo_end;
+  GBytes *zoneinfo;
+  GError *error = NULL;
+
+  if (identifier == NULL)
+    {
+      if (__system_property_get ("persist.sys.timezone", sys_timezone) < 1)
+        {
+          g_warning ("__system_property_get(\"persist.sys.timezone\") failed");
+          return NULL;
+        }
+      identifier = sys_timezone;
+    }
+
+  file = g_mapped_file_new ("/system/usr/share/zoneinfo/tzdata", FALSE, &error);
+  if (file == NULL)
+    {
+      g_warning ("Failed mapping tzdata file: %s", error->message);
+      g_error_free (error);
+      return NULL;
+    }
+
+  tzdata = g_mapped_file_get_contents (file);
+  tzdata_length = g_mapped_file_get_length (file);
+  if (tzdata == NULL || tzdata_length < 24)
+    {
+      g_warning ("Too small tzdata file");
+      goto error;
+    }
+
+  header_index_offset = gint32_from_be (*((gint32_be*) (tzdata + 12)));
+  header_data_offset = gint32_from_be (*((gint32_be*) (tzdata + 16)));
+
+  if (header_index_offset < 0 || header_data_offset < 0 || header_data_offset < index_entry_size)
+    {
+      g_warning ("Invalid tzdata content");
+      goto error;
+    }
+
+  entry_count = (header_data_offset - header_index_offset) / index_entry_size;
+  if (entry_count < 1)
+    {
+      g_warning ("No index entry found");
+      goto error;
+    }
+
+  current_index = 0;
+  while (current_index < entry_count)
+    {
+      if (!g_uint_checked_mul (&entry_name_start, current_index, index_entry_size) ||
+          !g_uint_checked_add (&entry_name_start, entry_name_start, header_index_offset) ||
+          !g_uint_checked_add (&entry_name_end, entry_name_start, 40))
+        {
+          g_warning ("Overflow when computing entry name offset");
+          goto error;
+        }
+
+      entry_name = tzdata + entry_name_start;
+
+      /* The name should be null terminated within the 40 chars. */
+      if (memchr (entry_name, 0, 40) == NULL)
+        {
+          g_warning ("Invalid index entry");
+          goto error;
+        }
+
+      if (strcmp (entry_name, identifier) == 0)
+        {
+          entry_offset = gint32_from_be (*(gint32_be*) (entry_name + 40));
+          entry_length = gint32_from_be (*(gint32_be*) (entry_name + 44));
+          if (entry_length == 0 || entry_length > 65536)
+            {
+              /* Use a reasonable but arbitrary max length of an entry. */
+              g_warning ("Invalid zoneinfo entry length");
+              goto error;
+            }
+
+          if (!g_uint_checked_add (&zoneinfo_start, header_data_offset, entry_offset) ||
+              !g_uint_checked_add (&zoneinfo_end, zoneinfo_start, entry_length) ||
+              zoneinfo_end > tzdata_length)
+            {
+              g_warning ("Too large zoneinfo entry length");
+              goto error;
+            }
+
+          zoneinfo = g_bytes_new_with_free_func (tzdata + zoneinfo_start,
+                                                 entry_length,
+                                                 (GDestroyNotify)g_mapped_file_unref,
+                                                 g_mapped_file_ref (file));
+          g_mapped_file_unref (file);
+
+          if (out_identifier != NULL)
+              *out_identifier = g_strdup (identifier);
+
+          return zoneinfo;
+        }
+      current_index++;
+    }
+
+error:
+  g_mapped_file_unref (file);
+  return NULL;
+}
+
+
+
 static GBytes*
 zone_info_unix (const gchar *identifier,
                 const gchar *resolved_identifier)
@@ -1773,7 +1906,7 @@
   if (tz->t_info == NULL)
     {
 #ifdef G_OS_UNIX
-      GBytes *zoneinfo = zone_info_unix (identifier, resolved_identifier);
+      GBytes *zoneinfo = zone_info_android(identifier, &resolved_identifier);
       if (zoneinfo != NULL)
         {
           init_zone_from_iana_info (tz, zoneinfo, g_steal_pointer (&resolved_identifier));