perl/Git.pm: "prompt" helper to honor GIT_ASKPASS and SSH_ASKPASS

git-svn reads passwords from an interactive terminal or by using
GIT_ASKPASS helper tool. But if GIT_ASKPASS environment variable is not
set, git-svn does not try to use SSH_ASKPASS as git-core does. This
cause GUIs (w/o STDIN connected) to hang waiting forever for git-svn to
complete (http://code.google.com/p/tortoisegit/issues/detail?id=967).

Earlier, 56a853b (git-svn: Support retrieving passwords with GIT_ASKPASS,
2010-03-02) tried to solve this issue, but was incomplete as described
above.

Instead of using hand-rolled prompt-response code that only works with the
interactive terminal and uses GIT_ASKPASS, introduce prompt() helper
function in Git.pm library that also pays attention to SSH_ASKPASS as a
fallback, and use it in git-svn. The result mimics the behaviour of the
core git better.

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Helped-by: Ævar Arnfjörð Bjarmason
Signed-off-by: Junio C Hamano <gitster@pobox.com>

2 files changed, 51 insertions, 20 deletions

diff --git a/git-svn.perl b/git-svn.perl
index e30df22d89..6a0117640d 100755
--- a/git-svn.perl
+++ b/git-svn.perl
@@ -4415,25 +4415,7 @@ sub username {
 
 sub _read_password {
 	my ($prompt, $realm) = @_;
-	my $password = '';
-	if (exists $ENV{GIT_ASKPASS}) {
-		open(PH, "-|", $ENV{GIT_ASKPASS}, $prompt);
-		$password = <PH>;
-		$password =~ s/[\012\015]//; # \n\r
-		close(PH);
-	} else {
-		print STDERR $prompt;
-		STDERR->flush;
-		require Term::ReadKey;
-		Term::ReadKey::ReadMode('noecho');
-		while (defined(my $key = Term::ReadKey::ReadKey(0))) {
-			last if $key =~ /[\012\015]/; # \n\r
-			$password .= $key;
-		}
-		Term::ReadKey::ReadMode('restore');
-		print STDERR "\n";
-		STDERR->flush;
-	}
+	my $password = Git::prompt($prompt);
 	$password;
 }
 
diff --git a/perl/Git.pm b/perl/Git.pm
index f7ce511bbb..46f11a89de 100644
--- a/perl/Git.pm
+++ b/perl/Git.pm
@@ -58,7 +58,7 @@ require Exporter;
                 command_output_pipe command_input_pipe command_close_pipe
                 command_bidi_pipe command_close_bidi_pipe
                 version exec_path html_path hash_object git_cmd_try
-                remote_refs
+                remote_refs prompt
                 temp_acquire temp_release temp_reset temp_path);
 
 
@@ -512,6 +512,55 @@ C<git --html-path>). Useful mostly only internally.
 sub html_path { command_oneline('--html-path') }
 
 
+=item prompt ( PROMPT )
+
+Query user C<PROMPT> and return answer from user.
+
+If an external helper is specified via GIT_ASKPASS or SSH_ASKPASS, it
+is used to interact with the user; otherwise the prompt is given to
+and the answer is read from the terminal.
+
+=cut
+
+sub prompt {
+	my ($prompt) = @_;
+	my $ret;
+	if (!defined $ret) {
+		$ret = _prompt($ENV{'GIT_ASKPASS'}, $prompt);
+	}
+	if (!defined $ret) {
+		$ret = _prompt($ENV{'SSH_ASKPASS'}, $prompt);
+	}
+	if (!defined $ret) {
+		$ret = '';
+		print STDERR $prompt;
+		STDERR->flush;
+		require Term::ReadKey;
+		Term::ReadKey::ReadMode('noecho');
+		while (defined(my $key = Term::ReadKey::ReadKey(0))) {
+			last if $key =~ /[\012\015]/; # \n\r
+			$ret .= $key;
+		}
+		Term::ReadKey::ReadMode('restore');
+		print STDERR "\n";
+		STDERR->flush;
+	}
+	return $ret;
+}
+
+sub _prompt {
+	my ($askpass, $prompt) = @_;
+	return unless ($askpass);
+
+	open my $fh, "-|", $askpass, $prompt
+		or return;
+	my $ret = <$fh>;
+	$ret =~ s/[\012\015]//g; # \n\r
+	close ($fh);
+	return $ret;
+}
+
+
 =item repo_path ()
 
 Return path to the git repository. Must be called on a repository instance.