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[lttngtop.git] / lib / babeltrace / compat / utc.h

diff --git a/lib/babeltrace/compat/utc.h b/lib/babeltrace/compat/utc.h
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+++ b/lib/babeltrace/compat/utc.h
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+#ifndef _BABELTRACE_UTC_H
+#define _BABELTRACE_UTC_H
+
+/*
+ * Copyright (C) 2011-2013 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+#include <time.h>
+
+/* If set, use GNU or BSD timegm(3) */
+#if defined(_BSD_SOURCE) || defined(_SVID_SOURCE)
+
+static inline
+time_t babeltrace_timegm(struct tm *tm)
+{
+       return timegm(tm);
+}
+
+#else
+
+#include <string.h>
+#include <stdlib.h>
+
+/*
+ * Note: Below implementation of timegm() is not thread safe
+ * as it changes the environment
+ * variable TZ. It is OK as long as it is kept in self-contained program,
+ * but should not be used within thread-safe library code.
+ */
+
+static inline
+time_t babeltrace_timegm(struct tm *tm)
+{
+       time_t ret;
+       char *tz;
+
+       tz = getenv("TZ");
+       /*
+        * Make a temporary copy, as the environment variable will be
+        * modified.
+        */
+       if (tz) {
+               tz = strdup(tz);
+               if (!tz) {
+                       /*
+                        * Memory allocation error.
+                        */
+                       return (time_t) -1;
+               }
+       }
+
+       /* Temporarily setting TZ to 1 for UTC */
+       setenv("TZ", "", 1);
+       tzset();
+       ret = mktime(tm);
+       if (tz) {
+               setenv("TZ", tz, 1);
+               free(tz);
+       } else {
+               unsetenv("TZ");
+       }
+       tzset();
+       return ret;
+}
+
+#endif
+
+#endif /* _BABELTRACE_UTC_H */