1 files changed, 51 insertions, 0 deletions
diff --git a/lib/time/day_to_str.h b/lib/time/day_to_str.h
new file mode 100644
index 0000000..96cec6e
--- /dev/null
+++ b/lib/time/day_to_str.h
@@ -0,0 +1,51 @@
+// SPDX-FileCopyrightText: 2021-2024, Alejandro Colomar <alx@kernel.org>
+// SPDX-FileCopyrightText: 2024, Tobias Stoeckmann <tobias@stoeckmann.org>
+// SPDX-License-Identifier: BSD-3-Clause
+
+
+#ifndef SHADOW_INCLUDE_LIB_TIME_DAY_TO_STR_H_
+#define SHADOW_INCLUDE_LIB_TIME_DAY_TO_STR_H_
+
+
+#include <config.h>
+
+#include <time.h>
+
+#include "defines.h"
+#include "sizeof.h"
+#include "string/strtcpy.h"
+
+
+#define DAY_TO_STR(str, day)   day_to_str(NITEMS(str), str, day)
+
+
+inline void day_to_str(size_t size, char buf[size], long day);
+
+
+inline void
+day_to_str(size_t size, char buf[size], long day)
+{
+	time_t     date;
+	struct tm  tm;
+
+	if (day < 0) {
+		strtcpy(buf, "never", size);
+		return;
+	}
+
+	if (__builtin_mul_overflow(day, DAY, &date)) {
+		strtcpy(buf, "future", size);
+		return;
+	}
+
+	if (gmtime_r(&date, &tm) == NULL) {
+		strtcpy(buf, "future", size);
+		return;
+	}
+
+	if (strftime(buf, size, "%Y-%m-%d", &tm) == 0)
+		strtcpy(buf, "future", size);
+}
+
+
+#endif  // include guard