date: catch invalid date arguments #908

mknos · 2025-01-06T04:36:55Z

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
Found when testing against GNU date
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

* 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

briandfoy · 2025-01-06T05:24:43Z

changes: all formats must start with + and there can only be one

briandfoy · 2025-01-07T08:11:07Z

I had to back out this change because it broke date -u, and maybe other things.

briandfoy · 2025-01-07T08:41:05Z

bin/date

@@ -80,8 +80,19 @@ sub run {
 	}

 sub select_format {
-	my( $supplied ) = grep { /\A\+/ } @_;
-	return $1 if $supplied =~ /\A\+(.+)/;
+	my $supplied;


I ended up backing out this change. I should have paid attention to the test failing, but there was another test failing so I just ignored both. That's dumb.

A few things to note here:

don't exit from utility subs. In the fix I die and wrap the sub in an eval. That gives the main code a chance to ignore it. Note a huge deal here because it's all private code, but in general it's about separation of concerns.

we can't stop if there is an option that doesn't start with + because there are other options possible, and maybe we need better argument processing so nothing else is left.

github-actions bot added Type: enhancement improve a feature that already exists Priority: low get to this whenever Program: date The date program labels Jan 6, 2025