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gtimezone: Split out fallback timezone identification for unix

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When the TZ environment variable is not set, we get the local timezone
identifier by reading specific files.

We are going to need these identifiers earlier, so split this logic into
its own function, in preparation for the next commit.

Based on idea proposed by Sebastian Keller <skeller@gnome.org>.
This commit is contained in:
António Fernandes 2020-09-23 18:13:47 +01:00
parent 53819d8a37
commit b4138bd4ac
1 changed files with 73 additions and 54 deletions
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127
glib/gtimezone.c
View File

@ -438,11 +438,80 @@ zone_for_constant_offset (GTimeZone *gtz, const gchar *name)
}
#ifdef G_OS_UNIX
static gchar *
zone_identifier_unix (void)
{
gchar *resolved_identifier = NULL;
gsize prefix_len = 0;
gchar *canonical_path = NULL;
GError *read_link_err = NULL;
const gchar *tzdir;
/* Resolve the actual timezone pointed to by /etc/localtime. */
resolved_identifier = g_file_read_link ("/etc/localtime", &read_link_err);
if (resolved_identifier == NULL)
{
gboolean not_a_symlink = g_error_matches (read_link_err,
G_FILE_ERROR,
G_FILE_ERROR_INVAL);
g_clear_error (&read_link_err);
/* Fallback to the content of /var/db/zoneinfo or /etc/timezone
* if /etc/localtime is not a symlink. /var/db/zoneinfo is
* where 'tzsetup' program on FreeBSD and DragonflyBSD stores
* the timezone chosen by the user. /etc/timezone is where user
* choice is expressed on Gentoo OpenRC and others. */
if (not_a_symlink && (g_file_get_contents ("/var/db/zoneinfo",
&resolved_identifier,
NULL, NULL) ||
g_file_get_contents ("/etc/timezone",
&resolved_identifier,
NULL, NULL)))
g_strchomp (resolved_identifier);
else
{
/* Error */
g_assert (resolved_identifier == NULL);
goto out;
}
}
else
{
/* Resolve relative path */
canonical_path = g_canonicalize_filename (resolved_identifier, "/etc");
g_free (resolved_identifier);
resolved_identifier = g_steal_pointer (&canonical_path);
}
tzdir = g_getenv ("TZDIR");
if (tzdir == NULL)
tzdir = "/usr/share/zoneinfo";
/* Strip the prefix and slashes if possible. */
if (g_str_has_prefix (resolved_identifier, tzdir))
{
prefix_len = strlen (tzdir);
while (*(resolved_identifier + prefix_len) == '/')
prefix_len++;
}
if (prefix_len > 0)
memmove (resolved_identifier, resolved_identifier + prefix_len,
strlen (resolved_identifier) - prefix_len + 1 /* nul terminator */);
g_assert (resolved_identifier != NULL);
out:
g_free (canonical_path);
return resolved_identifier;
}
static GBytes*
zone_info_unix (const gchar *identifier,
gchar **out_identifier)
{
gchar *filename;
gchar *filename = NULL;
GMappedFile *file = NULL;
GBytes *zoneinfo = NULL;
gchar *resolved_identifier = NULL;
@ -470,61 +539,11 @@ zone_info_unix (const gchar *identifier,
}
else
{
gsize prefix_len = 0;
gchar *canonical_path = NULL;
GError *read_link_err = NULL;
resolved_identifier = zone_identifier_unix ();
if (resolved_identifier == NULL)
goto out;
filename = g_strdup ("/etc/localtime");
/* Resolve the actual timezone pointed to by /etc/localtime. */
resolved_identifier = g_file_read_link (filename, &read_link_err);
if (resolved_identifier == NULL)
{
gboolean not_a_symlink = g_error_matches (read_link_err,
G_FILE_ERROR,
G_FILE_ERROR_INVAL);
g_clear_error (&read_link_err);
/* Fallback to the content of /var/db/zoneinfo or /etc/timezone
* if /etc/localtime is not a symlink. /var/db/zoneinfo is
* where 'tzsetup' program on FreeBSD and DragonflyBSD stores
* the timezone chosen by the user. /etc/timezone is where user
* choice is expressed on Gentoo OpenRC and others. */
if (not_a_symlink && (g_file_get_contents ("/var/db/zoneinfo",
&resolved_identifier,
NULL, NULL) ||
g_file_get_contents ("/etc/timezone",
&resolved_identifier,
NULL, NULL)))
g_strchomp (resolved_identifier);
else
{
/* Error */
g_assert (resolved_identifier == NULL);
goto out;
}
}
else
{
/* Resolve relative path */
canonical_path = g_canonicalize_filename (resolved_identifier, "/etc");
g_free (resolved_identifier);
resolved_identifier = g_steal_pointer (&canonical_path);
}
/* Strip the prefix and slashes if possible. */
if (g_str_has_prefix (resolved_identifier, tzdir))
{
prefix_len = strlen (tzdir);
while (*(resolved_identifier + prefix_len) == '/')
prefix_len++;
}
if (prefix_len > 0)
memmove (resolved_identifier, resolved_identifier + prefix_len,
strlen (resolved_identifier) - prefix_len + 1 /* nul terminator */);
g_free (canonical_path);
}
file = g_mapped_file_new (filename, FALSE, NULL);