[systemd-devel] [PATCH] timedated: gather timezone from /etc/localtime sym target

[shawnlandden at gmail.com]

From: Shawn Landen <shawnlandden at gmail.com>

keep other method for now, consider dropping later.

Supporting relative links here could be problematic as timezones in
/usr/share/zoneinfo are often themselves symlinks (and symlinks to
symlinks), so this implamentation only only support absolute links.
---
 src/timedate/timedated.c |   30 ++++++++++++++++++++++++++++++
 1 file changed, 30 insertions(+)

diff --git a/src/timedate/timedated.c b/src/timedate/timedated.c
index 09fd808..d0812fa 100644
--- a/src/timedate/timedated.c
+++ b/src/timedate/timedated.c
@@ -24,6 +24,7 @@
 #include <errno.h>
 #include <string.h>
 #include <unistd.h>
+#include <sys/stat.h>
 
 #include "util.h"
 #include "strv.h"
@@ -74,6 +75,11 @@
         BUS_GENERIC_INTERFACES_LIST             \
         "org.freedesktop.timedate1\0"
 
+/* Must start and end with '/' */
+#ifndef ZONEINFO_PATH
+#  define ZONEINFO_PATH "/usr/share/zoneinfo/"
+#endif
+
 const char timedate_interface[] _introspect_("timedate1") = INTERFACE;
 
 typedef struct TZ {
@@ -174,9 +180,32 @@ static void verify_timezone(void) {
 
 static int read_data(void) {
         int r;
+        struct stat st;
+        char *t;
 
         free_data();
 
+        r = readlink_malloc("/etc/localtime", &t);
+        if (r < 0) {
+                if (errno == EINVAL)
+                        log_warning("/etc/localtime should be an absolute symlink to a timezone data file in %s", ZONEINFO_PATH);
+                else
+                        log_warning("Failed to get target of %s: %m", "/etc/localtime");
+        } else if (!startswith(t, ZONEINFO_PATH))
+                log_warning("/etc/localtime should be an absolute symlink to a timezone data file in %s", ZONEINFO_PATH);
+        else {
+                tz.zone = strdup(t + strlen(ZONEINFO_PATH));
+                if (!tz.zone) {
+                        free(t);
+                        return log_oom();
+                }
+
+                free(t);
+                goto have_timeone;
+        }
+
+        free(t);
+
         r = read_one_line_file("/etc/timezone", &tz.zone);
         if (r < 0) {
                 if (r != -ENOENT)
@@ -192,6 +221,7 @@ static int read_data(void) {
 #endif
         }
 
+have_timezone:
         if (isempty(tz.zone)) {
                 free(tz.zone);
                 tz.zone = NULL;
-- 
1.7.10.4