From 2a9c361b7e9d32ca4ffb40b80a714885bc5b64a6 Mon Sep 17 00:00:00 2001
From: P. J. McDermott <pj@pehjota.net>
Date: Sun, 29 Aug 2021 16:03:51 -0400
Subject: main: Prevent dates too large to consistently show

---
diff --git a/configure.ac b/configure.ac
index e1c9f6c..12dc4cf 100644
--- a/configure.ac
+++ b/configure.ac
@@ -38,8 +38,8 @@ test -d "${srcdir}/.git" || CFLAGS="${save_CFLAGS}"
 funcs_missing=false
 AC_CHECK_FUNCS(
 	[\
-		calloc fprintf free localtime mktime printf setvbuf sleep \
-		strerror strlen strptime time
+		calloc fprintf fputs free localtime mktime printf setvbuf \
+		sleep strerror strlen strptime time
 	],
 	[],
 	[funcs_missing=true])
diff --git a/src/main.c b/src/main.c
index 00e0ef7..4ad711c 100644
--- a/src/main.c
+++ b/src/main.c
@@ -78,10 +78,15 @@ main(int argc, const char *argv[])
 	}
 	free(buf);
 
-	setvbuf(stdout, NULL, _IONBF, 0);
 	time(&now);
+	dif = arg - now;
+	if (dif >= 1000 * 24 * 60 * 60) {
+		fputs("Date too far in the future\n", stderr);
+		return EXIT_FAILURE;
+	}
+
+	setvbuf(stdout, NULL, _IONBF, 0);
 	while (arg > now) {
-		dif = arg - now;
 		printf("\r%03d:%02d:%02d:%02d",
 				(int) dif / 60 / 60 / 24,
 				(int) dif / 60 / 60 % 24,
@@ -89,6 +94,7 @@ main(int argc, const char *argv[])
 				(int) dif % 60);
 		sleep(1);
 		time(&now);
+		dif = arg - now;
 	}
 	printf("\r000:00:00:00\n");
 
--
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