1 files changed, 89 insertions, 0 deletions
diff --git a/libmisc/gettime.c b/libmisc/gettime.c
new file mode 100644
index 0000000..53eaf51
--- /dev/null
+++ b/libmisc/gettime.c
@@ -0,0 +1,89 @@
+/*
+ * Copyright (c) 2017, Chris Lamb
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the copyright holders or contributors may not be used to
+ *    endorse or promote products derived from this software without
+ *    specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
+ * PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT
+ * HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <config.h>
+
+#ident "$Id$"
+
+#include <errno.h>
+#include <limits.h>
+#include <stdio.h>
+#include "defines.h"
+#include "prototypes.h"
+
+/*
+ * gettime() returns the time as the number of seconds since the Epoch
+ *
+ * Like time(), gettime() returns the time as the number of seconds since the
+ * Epoch, 1970-01-01 00:00:00 +0000 (UTC), except that if the SOURCE_DATE_EPOCH
+ * environment variable is exported it will use that instead.
+ */
+/*@observer@*/time_t gettime ()
+{
+	char *endptr;
+	char *source_date_epoch;
+	time_t fallback;
+	unsigned long long epoch;
+
+	fallback = time (NULL);
+	source_date_epoch = getenv ("SOURCE_DATE_EPOCH");
+
+	if (!source_date_epoch)
+		return fallback;
+
+	errno = 0;
+	epoch = strtoull (source_date_epoch, &endptr, 10);
+	if ((errno == ERANGE && (epoch == ULLONG_MAX || epoch == 0))
+			|| (errno != 0 && epoch == 0)) {
+		fprintf (stderr,
+			 _("Environment variable $SOURCE_DATE_EPOCH: strtoull: %s\n"),
+			 strerror(errno));
+	} else if (endptr == source_date_epoch) {
+		fprintf (stderr,
+			 _("Environment variable $SOURCE_DATE_EPOCH: No digits were found: %s\n"),
+			 endptr);
+	} else if (*endptr != '\0') {
+		fprintf (stderr,
+			 _("Environment variable $SOURCE_DATE_EPOCH: Trailing garbage: %s\n"),
+			 endptr);
+	} else if (epoch > ULONG_MAX) {
+		fprintf (stderr,
+			 _("Environment variable $SOURCE_DATE_EPOCH: value must be smaller than or equal to %lu but was found to be: %llu\n"),
+			 ULONG_MAX, epoch);
+	} else if (epoch > fallback) {
+		fprintf (stderr,
+			 _("Environment variable $SOURCE_DATE_EPOCH: value must be smaller than or equal to the current time (%lu) but was found to be: %llu\n"),
+			 fallback, epoch);
+	} else {
+		/* Valid */
+		return (time_t)epoch;
+	}
+
+	return fallback;
+}