send-email: detect empty blank lines in command output

The email format does not allow blank lines in headers; detect such
input and report it as malformed and add a test for it.

Signed-off-by: Maxim Cournoyer <maxim.cournoyer@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 10 insertions, 2 deletions

diff --git a/git-send-email.perl b/git-send-email.perl
index 32febe9af3..22a64e608f 100755
--- a/git-send-email.perl
+++ b/git-send-email.perl
@@ -2026,14 +2026,22 @@ foreach my $t (@files) {
 	}
 }
 
-# Execute a command and return its output lines as an array.
+# Execute a command and return its output lines as an array.  Blank
+# lines which do not appear at the end of the output are reported as
+# errors.
 sub execute_cmd {
 	my ($prefix, $cmd, $file) = @_;
 	my @lines = ();
+	my $seen_blank_line = 0;
 	open my $fh, "-|", "$cmd \Q$file\E"
 		or die sprintf(__("(%s) Could not execute '%s'"), $prefix, $cmd);
 	while (my $line = <$fh>) {
-		last if $line =~ /^$/;
+		die sprintf(__("(%s) Malformed output from '%s'"), $prefix, $cmd)
+		    if $seen_blank_line;
+		if ($line =~ /^$/) {
+			$seen_blank_line = $line =~ /^$/;
+			next;
+		}
 		push @lines, $line;
 	}
 	close $fh