1  #include <time.h>
       2  #include <stdlib.h>
       3  
       4  /* timegm -- based on Linux timegm man page */
       5  
       6  time_t
       7  timegm(struct tm *tm)
       8  {
       9  	time_t ret;
      10  	char *tz = getenv("TZ");
      11  	const char *tzreq = "UTC+0";	/* more portable than ""? */
      12  
      13  	if (tz)
      14  		tz = estrdup(tz, strlen(tz));
      15  	if (setenv("TZ", tzreq, 1) < 0) {
      16  		warning(_("setenv(TZ, %s) failed (%s)"), tzreq, strerror(errno));
      17  		return -1;
      18  	}
      19  	tzset();
      20  	ret = mktime(tm);
      21  	if (tz) {
      22  		if (setenv("TZ", tz, 1) < 0)
      23  			fatal(_("setenv(TZ, %s) restoration failed (%s)"), tz, strerror(errno));
      24  		free(tz);
      25  	} else {
      26  		if (unsetenv("TZ") < 0)
      27  			fatal(_("unsetenv(TZ) failed (%s)"), strerror(errno));
      28  	}
      29  	tzset();
      30  	return ret;
      31  }