[PATCH] send-email: Ask if a patch should be sent twice

[Dmitry Safonov <dima@arista.com>]

I was almost certain that git won't let me send the same patch twice,
but today I've managed to double-send a directory by a mistake:
	git send-email --to linux-kernel@vger.kernel.org /tmp/timens/
	    --cc 'Dmitry Safonov <0x7f454c46@gmail.com>' /tmp/timens/`

[I haven't noticed that I put the directory twice ^^]

Prevent this shipwreck from happening again by asking if a patch
is sent multiple times on purpose.

link: https://lkml.kernel.org/r/4d53ebc7-d5b2-346e-c383-606401d19d3a@gmail.com
Cc: Andrei Vagin <avagin@openvz.org>
Signed-off-by: Dmitry Safonov <dima@arista.com>
---
 git-send-email.perl | 23 ++++++++++++++++++++++-
 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/git-send-email.perl b/git-send-email.perl
index 5f92c89c1c1b..0caafc104478 100755
--- a/git-send-email.perl
+++ b/git-send-email.perl
@@ -33,6 +33,7 @@
 use Net::Domain ();
 use Net::SMTP ();
 use Git::LoadCPAN::Mail::Address;
+use experimental 'smartmatch';
 
 Getopt::Long::Configure qw/ pass_through /;
 
@@ -658,6 +659,17 @@ sub is_format_patch_arg {
 	}
 }
 
+sub send_file_twice {
+	my $f = shift;
+	$_ = ask(__("Patch $f will be sent twice, continue? [y]/n "),
+		default => "y",
+		valid_re => qr/^(?:yes|y|no|n)/i);
+	if (/^n/i) {
+		cleanup_compose_files();
+		exit(0);
+	}
+}
+
 # Now that all the defaults are set, process the rest of the command line
 # arguments and collect up the files that need to be processed.
 my @rev_list_opts;
@@ -669,10 +681,19 @@ sub is_format_patch_arg {
 		opendir my $dh, $f
 			or die sprintf(__("Failed to opendir %s: %s"), $f, $!);
 
-		push @files, grep { -f $_ } map { catfile($f, $_) }
+		my @new_files = grep { -f $_ } map { catfile($f, $_) }
 				sort readdir $dh;
+		foreach my $nfile (@new_files) {
+			if ($nfile ~~ @files) {
+				send_file_twice($nfile);
+			}
+		}
+		push @files, @new_files;
 		closedir $dh;
 	} elsif ((-f $f or -p $f) and !is_format_patch_arg($f)) {
+		if ($f ~~ @files) {
+			send_file_twice($f);
+		}
 		push @files, $f;
 	} else {
 		push @rev_list_opts, $f;
-- 
2.22.0