From 73ebb68b0749573a97d3354d111f7174717d29b7 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Petr=20P=C3=ADsa=C5=99?= <petr.pisar@atlas.cz>
Date: Wed, 2 Dec 2009 14:05:37 +0100
Subject: [PATCH] Switch TZ at mktime() temporarily

---
 src/isds.c  |  3 ++-
 src/utils.c | 41 +++++++++++++++++++++++++++++++++++++++++
 src/utils.h |  8 ++++++++
 3 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/src/isds.c b/src/isds.c
index 8a6048d..8de970b 100644
--- a/src/isds.c
+++ b/src/isds.c
@@ -974,8 +974,9 @@ static isds_error timestring2timeval(const xmlChar *string,
     }
 
     /* Convert to time_t */
-    /* FIXME: Don't run-time TZ */
+    switch_tz_to_utc();
     (*time)->tv_sec = mktime(&broken);
+    switch_tz_to_native();
     if ((*time)->tv_sec == (time_t) -1) {
         free(*time); *time = NULL;
         return IE_DATE;
diff --git a/src/utils.c b/src/utils.c
index 8418424..5c1155a 100644
--- a/src/utils.c
+++ b/src/utils.c
@@ -1,11 +1,16 @@
+#define _XOPEN_SOURCE 500 /* For strdup(3) */
+#define _POSIX_C_SOURCE 200112L /* For setenv() */
 #include <string.h>
 #include <stdlib.h>
 #include <stdio.h>
 #include <iconv.h>
 #include <langinfo.h>
+#include <time.h>
 #include "utils.h"
 #include "cencode.h"
 
+char *tz_orig; /* Copy of original TZ variable */
+
 /* Concatenate two strings into newly allocated buffer.
  * You must free() them, when you don't need it anymore.
  * Any of the arguments can be NULL meaning empty string.
@@ -218,3 +223,39 @@ _hidden char *b64encode(const void *plain, const size_t length) {
     return buffer;
 }
 
+
+/* Switches time zone to UTC.
+ * XXX: This is not reentrant and not thread-safe */
+_hidden void switch_tz_to_utc(void) {
+    char *tz;
+
+    tz = getenv("TZ");
+    if (tz) {
+        tz_orig = strdup(tz);
+        if (!tz_orig) 
+            PANIC("Can not back original time zone up");
+    } else {
+        tz_orig = NULL;
+    }
+
+    if (setenv("TZ", "", 1))
+            PANIC("Can not change time zone to UTC temporarily");
+
+    tzset();
+}
+
+
+/* Switches time zone to original value.
+ * XXX: This is not reentrant and not thread-safe */
+_hidden void switch_tz_to_native(void) {
+    if (tz_orig) {
+        if (setenv("TZ", tz_orig, 1))
+            PANIC("Can not restore time zone by setting TZ variable");
+        free(tz_orig);
+        tz_orig = NULL;
+    } else {
+        if(unsetenv("TZ"))
+            PANIC("Can not restore time zone by unsetting TZ variable");
+    }
+    tzset();
+}
diff --git a/src/utils.h b/src/utils.h
index 8f55c1c..ea4eb73 100644
--- a/src/utils.h
+++ b/src/utils.h
@@ -64,4 +64,12 @@ char *utf82locale(const char *utf);
  * error. You must free it. */
 char *b64encode(const void *plain, const size_t length);
 
+/* Switches time zone to UTC.
+ * XXX: This is not reentrant and not thread-safe */
+_hidden void switch_tz_to_utc(void);
+
+/* Switches time zone to original value.
+ * XXX: This is not reentrant and not thread-safe */
+_hidden void switch_tz_to_native(void);
+
 #endif
-- 
2.11.4.GIT