From 8433ab449bf3748f3d35090d7aedab85956beff0 Mon Sep 17 00:00:00 2001
From: Michael Mikonos <127171689+mknos@users.noreply.github.com>
Date: Mon, 6 Jan 2025 12:34:59 +0800
Subject: [PATCH] date: catch invalid date arguments

* Extra format string arguments are ambiguous and should result in an error
* select_format() is meant to select only one format; the use of grep() as a filter prevented it from catching invalid arguments
* Arguments which are not a valid format string should result in an error
* test1: perl date    # default in select_format()
* test2: perl date yo+%a   # not a valid date format
* test3: perl date +%a +%a    # too many formats
* test4: perl date +%a%a   # still works
---
 bin/date | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/bin/date b/bin/date
index ce5136ff..686ce96d 100755
--- a/bin/date
+++ b/bin/date
@@ -16,7 +16,7 @@ License: artistic2
 
 use POSIX;
 
-my $VERSION = '1.0.4';
+my $VERSION = '1.0.5';
 
 # set this if we do anything to select a timezone abbreviation, then
 # prefer this if it is defined.
@@ -80,8 +80,19 @@ sub run {
 	}
 
 sub select_format {
-	my( $supplied ) = grep { /\A\+/ } @_;
-	return $1 if $supplied =~ /\A\+(.+)/;
+	my $supplied;
+	foreach (@_) {
+		unless (s/\A\+//) {
+			print STDERR "Invalid date: $_\n";
+			exit 1;
+		}
+		if (defined $supplied) {
+			print STDERR "Extra operand: '+$_'\n";
+			exit 1;
+		}
+		$supplied = $_;
+	}
+	return $supplied if defined $supplied;
 
 	my $formats = get_formats();