1 files changed, 68 insertions, 0 deletions
diff --git a/libmisc/gettime.c b/libmisc/gettime.c
new file mode 100644
index 0000000..b288402
--- /dev/null
+++ b/libmisc/gettime.c
@@ -0,0 +1,68 @@
+/*
+ * SPDX-FileCopyrightText: 2017, Chris Lamb
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#include <config.h>
+
+#ident "$Id$"
+
+#include <errno.h>
+#include <limits.h>
+#include <stdio.h>
+#include "defines.h"
+#include "prototypes.h"
+#include "shadowlog.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;
+	FILE *shadow_logfd = log_get_logfd();
+
+	fallback = time (NULL);
+	source_date_epoch = shadow_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 (shadow_logfd,
+			 _("Environment variable $SOURCE_DATE_EPOCH: strtoull: %s\n"),
+			 strerror(errno));
+	} else if (endptr == source_date_epoch) {
+		fprintf (shadow_logfd,
+			 _("Environment variable $SOURCE_DATE_EPOCH: No digits were found: %s\n"),
+			 endptr);
+	} else if (*endptr != '\0') {
+		fprintf (shadow_logfd,
+			 _("Environment variable $SOURCE_DATE_EPOCH: Trailing garbage: %s\n"),
+			 endptr);
+	} else if (epoch > ULONG_MAX) {
+		fprintf (shadow_logfd,
+			 _("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 (shadow_logfd,
+			 _("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;
+}