Speed up UTC mktime by using library timegm if available instead of our slow implementation.

9 files changed, 55 insertions, 31 deletions

diff --git a/ChangeLog b/ChangeLog
index b20df749..eaf475d5 100755
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2018-12-12         Andrew J. Schorr      <aschorr@telemetry-investments.com>
+
+	* configure.ac (AC_CHECK_FUNCS): Check for timegm.
+	* builtin.c (mktime_tz): Remove function; we will use timegm instead.
+	(do_mktime): Replace 'mktime_tz(& then, "UTC+0")' with 'timegm(& then)'.
+	* protos.h (timegm): Add timegm proto on systems lacking it.
+	* replace.c (timegm): Include missing_d/timegm.c if needed.
+
 2018-12-06         Arnold D. Robbins     <arnold@skeeve.com>
 
 	* configure.ac: Add -ggdb3 to CFLAGS if developing and remove
diff --git a/builtin.c b/builtin.c
index d7b2337e..f2d31059 100644
--- a/builtin.c
+++ b/builtin.c
@@ -2096,34 +2096,6 @@ do_systime(int nargs ATTRIBUTE_UNUSED)
 	return make_number((AWKNUM) lclock);
 }
 
-/* mktime_tz --- based on Linux timegm man page */
-
-static time_t
-mktime_tz(struct tm *tm, const char *tzreq)
-{
-	time_t ret;
-	char *tz = getenv("TZ");
-
-	if (tz)
-		tz = estrdup(tz, strlen(tz));
-	if (setenv("TZ", tzreq, 1) < 0) {
-		warning(_("setenv(TZ, %s) failed (%s)"), tzreq, strerror(errno));
-		return -1;
-	}
-	tzset();
-	ret = mktime(tm);
-	if (tz) {
-		if (setenv("TZ", tz, 1) < 0)
-			fatal(_("setenv(TZ, %s) restoration failed (%s)"), tz, strerror(errno));
-		free(tz);
-	} else {
-		if (unsetenv("TZ") < 0)
-			fatal(_("unsetenv(TZ) failed (%s)"), strerror(errno));
-	}
-	tzset();
-	return ret;
-}
-
 /* do_mktime --- turn a time string into a timestamp */
 
 NODE *
@@ -2184,7 +2156,7 @@ do_mktime(int nargs)
 	then.tm_year = year - 1900;
 	then.tm_isdst = dst;
 
-	then_stamp = (do_gmt ? mktime_tz(& then, "UTC+0") : mktime(& then));
+	then_stamp = (do_gmt ? timegm(& then) : mktime(& then));
 	return make_number((AWKNUM) then_stamp);
 }
 
diff --git a/configh.in b/configh.in
index 8c4d94d1..85adc147 100644
--- a/configh.in
+++ b/configh.in
@@ -279,6 +279,9 @@
 /* Define to 1 if you have the <termios.h> header file. */
 #undef HAVE_TERMIOS_H
 
+/* Define to 1 if you have the `timegm' function. */
+#undef HAVE_TIMEGM
+
 /* Define to 1 if you have the `tmpfile' function. */
 #undef HAVE_TMPFILE
 
diff --git a/configure b/configure
index b3ba275b..f488b48d 100755
--- a/configure
+++ b/configure
@@ -9982,7 +9982,7 @@ for ac_func in __etoa_l atexit btowc fmod gai_strerror \
 	memset_ulong mkstemp posix_openpt setenv setlocale setsid sigprocmask \
 	snprintf strchr \
 	strerror strftime strcasecmp strncasecmp strcoll strtod strtoul \
-	system tmpfile towlower towupper tzset usleep waitpid wcrtomb \
+	system timegm tmpfile towlower towupper tzset usleep waitpid wcrtomb \
 	wcscoll wctype
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
diff --git a/configure.ac b/configure.ac
index c6c7e501..bbc87b9e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -312,7 +312,7 @@ AC_CHECK_FUNCS(__etoa_l atexit btowc fmod gai_strerror \
 	memset_ulong mkstemp posix_openpt setenv setlocale setsid sigprocmask \
 	snprintf strchr \
 	strerror strftime strcasecmp strncasecmp strcoll strtod strtoul \
-	system tmpfile towlower towupper tzset usleep waitpid wcrtomb \
+	system timegm tmpfile towlower towupper tzset usleep waitpid wcrtomb \
 	wcscoll wctype)
 dnl this check is for both mbrtowc and the mbstate_t type, which is good
 AC_FUNC_MBRTOWC
diff --git a/missing_d/ChangeLog b/missing_d/ChangeLog
index bc54838f..2d69087a 100644
--- a/missing_d/ChangeLog
+++ b/missing_d/ChangeLog
@@ -1,3 +1,7 @@
+2018-12-12         Andrew J. Schorr     <aschorr@telemetry-investments.com>
+
+	* timegm.c: New file implementing timegm.
+
 2018-10-03         Arnold D. Robbins     <arnold@skeeve.com>
 
 	* intprops.h, verify.h: Removed. The copy in ../support is
diff --git a/missing_d/timegm.c b/missing_d/timegm.c
new file mode 100644
index 00000000..f7b780de
--- /dev/null
+++ b/missing_d/timegm.c
@@ -0,0 +1,29 @@
+#include <time.h>
+#include <stdlib.h>
+
+static time_t
+timegm(struct tm *tm)
+{
+	time_t ret;
+	char *tz = getenv("TZ");
+	const char *tzreq = "UTC+0";	/* more portable than ""? */
+
+	if (tz)
+		tz = estrdup(tz, strlen(tz));
+	if (setenv("TZ", tzreq, 1) < 0) {
+		warning(_("setenv(TZ, %s) failed (%s)"), tzreq, strerror(errno));
+		return -1;
+	}
+	tzset();
+	ret = mktime(tm);
+	if (tz) {
+		if (setenv("TZ", tz, 1) < 0)
+			fatal(_("setenv(TZ, %s) restoration failed (%s)"), tz, strerror(errno));
+		free(tz);
+	} else {
+		if (unsetenv("TZ") < 0)
+			fatal(_("unsetenv(TZ) failed (%s)"), strerror(errno));
+	}
+	tzset();
+	return ret;
+}
diff --git a/protos.h b/protos.h
index 5693a43b..4dd4a221 100644
--- a/protos.h
+++ b/protos.h
@@ -129,6 +129,10 @@ extern void tzset();
 extern time_t mktime(struct tm *tp);
 #endif
 
+#ifndef HAVE_TIMEGM
+extern time_t timegm(struct tm *);
+#endif
+
 #ifndef HAVE_SNPRINTF
 extern int snprintf(char *restrict buf, size_t len, const char *restrict fmt, ...);
 #endif
diff --git a/replace.c b/replace.c
index db7f0893..ae069f5b 100644
--- a/replace.c
+++ b/replace.c
@@ -91,6 +91,10 @@
 #include "missing_d/mktime.c"
 #endif /* HAVE_MKTIME */
 
+#ifndef HAVE_TIMEGM
+#include "missing_d/timegm.c"
+#endif /* HAVE_TIMEGM */
+
 #ifndef HAVE_SNPRINTF
 #include "missing_d/snprintf.c"
 #endif