add -i: ignore terminal escape sequences

On the author's terminal, the up-arrow input sequence is ^[[A, and
thus fat-fingering an up-arrow into 'git checkout -p' is quite
dangerous: git-add--interactive.perl will ignore the ^[ and [
characters and happily treat A as "discard everything".

As a band-aid fix, use Term::Cap to get all terminal capabilities.
Then use the heuristic that any capability value that starts with ^[
(i.e., \e in perl) must be a key input sequence.  Finally, given an
input that starts with ^[, read more characters until we have read a
full escape sequence, then return that to the caller.  We use a
timeout of 0.5 seconds on the subsequent reads to avoid getting stuck
if the user actually input a lone ^[.

Since none of the currently recognized keys start with ^[, the net
result is that the sequence as a whole will be ignored and the help
displayed.

Signed-off-by: Thomas Rast <trast@student.ethz.ch>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/git-add--interactive.perl b/git-add--interactive.perl
index 4f08fe704bbaff64613ab07630a71da8bf8bbca0..8f0839d205e0c4010e256bb5cf81c73cc2f438ab 100755 (executable)
--- a/git-add--interactive.perl
+++ b/git-add--interactive.perl
@@ -45,6 +45,9 @@ my ($diff_new_color) =
 my $normal_color = $repo->get_color("", "reset");
 
 my $use_readkey = 0;
+my $use_termcap = 0;
+my %term_escapes;
+
 sub ReadMode;
 sub ReadKey;
 if ($repo->config_bool("interactive.singlekey")) {
@@ -53,6 +56,14 @@ if ($repo->config_bool("interactive.singlekey")) {
                Term::ReadKey->import;
                $use_readkey = 1;
        };
+       eval {
+               require Term::Cap;
+               my $termcap = Term::Cap->Tgetent;
+               foreach (values %$termcap) {
+                       $term_escapes{$_} = 1 if /^\e/;
+               }
+               $use_termcap = 1;
+       };
 }
 
 sub colored {
@@ -1067,6 +1078,14 @@ sub prompt_single_character {
                ReadMode 'cbreak';
                my $key = ReadKey 0;
                ReadMode 'restore';
+               if ($use_termcap and $key eq "\e") {
+                       while (!defined $term_escapes{$key}) {
+                               my $next = ReadKey 0.5;
+                               last if (!defined $next);
+                               $key .= $next;
+                       }
+                       $key =~ s/\e/^[/;
+               }
                print "$key" if defined $key;
                print "\n";
                return $key;