Merge branch 'mn/send-email-works-with-credential'

Hooks the credential system to send-email.

* mn/send-email-works-with-credential:
  git-send-email: use git credential to obtain password
  Git.pm: add interface for git credential command
  Git.pm: allow pipes to be closed prior to calling command_close_bidi_pipe
  Git.pm: refactor command_close_bidi_pipe to use _cmd_close
  Git.pm: fix example in command_close_bidi_pipe documentation
  Git.pm: allow command_close_bidi_pipe to be called as method

3 files changed, 222 insertions, 51 deletions

diff --git a/Documentation/git-send-email.txt b/Documentation/git-send-email.txt
index 44a1f7c4e8..0cffef8aa5 100644
--- a/Documentation/git-send-email.txt
+++ b/Documentation/git-send-email.txt
@@ -164,8 +164,8 @@ Sending
 Furthermore, passwords need not be specified in configuration files
 or on the command line. If a username has been specified (with
 '--smtp-user' or a 'sendemail.smtpuser'), but no password has been
-specified (with '--smtp-pass' or 'sendemail.smtppass'), then the
-user is prompted for a password while the input is masked for privacy.
+specified (with '--smtp-pass' or 'sendemail.smtppass'), then
+a password is obtained using 'git-credential'.
 
 --smtp-server=<host>::
 	If set, specifies the outgoing SMTP server to use (e.g.
diff --git a/git-send-email.perl b/git-send-email.perl
index be809e5b59..c3501d987e 100755
--- a/git-send-email.perl
+++ b/git-send-email.perl
@@ -1045,6 +1045,47 @@ sub maildomain {
 	return maildomain_net() || maildomain_mta() || 'localhost.localdomain';
 }
 
+sub smtp_host_string {
+	if (defined $smtp_server_port) {
+		return "$smtp_server:$smtp_server_port";
+	} else {
+		return $smtp_server;
+	}
+}
+
+# Returns 1 if authentication succeeded or was not necessary
+# (smtp_user was not specified), and 0 otherwise.
+
+sub smtp_auth_maybe {
+	if (!defined $smtp_authuser || $auth) {
+		return 1;
+	}
+
+	# Workaround AUTH PLAIN/LOGIN interaction defect
+	# with Authen::SASL::Cyrus
+	eval {
+		require Authen::SASL;
+		Authen::SASL->import(qw(Perl));
+	};
+
+	# TODO: Authentication may fail not because credentials were
+	# invalid but due to other reasons, in which we should not
+	# reject credentials.
+	$auth = Git::credential({
+		'protocol' => 'smtp',
+		'host' => smtp_host_string(),
+		'username' => $smtp_authuser,
+		# if there's no password, "git credential fill" will
+		# give us one, otherwise it'll just pass this one.
+		'password' => $smtp_authpass
+	}, sub {
+		my $cred = shift;
+		return !!$smtp->auth($cred->{'username'}, $cred->{'password'});
+	});
+
+	return $auth;
+}
+
 # Returns 1 if the message was sent, and 0 otherwise.
 # In actuality, the whole program dies when there
 # is an error sending a message.
@@ -1155,9 +1196,7 @@ X-Mailer: git-send-email $gitversion
 		else {
 			require Net::SMTP;
 			$smtp_domain ||= maildomain();
-			$smtp ||= Net::SMTP->new((defined $smtp_server_port)
-						 ? "$smtp_server:$smtp_server_port"
-						 : $smtp_server,
+			$smtp ||= Net::SMTP->new(smtp_host_string(),
 						 Hello => $smtp_domain,
 						 Debug => $debug_net_smtp);
 			if ($smtp_encryption eq 'tls' && $smtp) {
@@ -1185,31 +1224,7 @@ X-Mailer: git-send-email $gitversion
 			    defined $smtp_server_port ? " port=$smtp_server_port" : "";
 		}
 
-		if (defined $smtp_authuser) {
-			# Workaround AUTH PLAIN/LOGIN interaction defect
-			# with Authen::SASL::Cyrus
-			eval {
-				require Authen::SASL;
-				Authen::SASL->import(qw(Perl));
-			};
-
-			if (!defined $smtp_authpass) {
-
-				system "stty -echo";
-
-				do {
-					print "Password: ";
-					$_ = <STDIN>;
-					print "\n";
-				} while (!defined $_);
-
-				chomp($smtp_authpass = $_);
-
-				system "stty echo";
-			}
-
-			$auth ||= $smtp->auth( $smtp_authuser, $smtp_authpass ) or die $smtp->message;
-		}
+		smtp_auth_maybe or die $smtp->message;
 
 		$smtp->mail( $raw_from ) or die $smtp->message;
 		$smtp->to( @recipients ) or die $smtp->message;
diff --git a/perl/Git.pm b/perl/Git.pm
index 57a17160f9..96cac39a4c 100644
--- a/perl/Git.pm
+++ b/perl/Git.pm
@@ -60,6 +60,7 @@ require Exporter;
                 version exec_path html_path hash_object git_cmd_try
                 remote_refs prompt
                 get_tz_offset
+                credential credential_read credential_write
                 temp_acquire temp_release temp_reset temp_path);
 
 
@@ -269,13 +270,13 @@ sub command {
 
 	if (not defined wantarray) {
 		# Nothing to pepper the possible exception with.
-		_cmd_close($fh, $ctx);
+		_cmd_close($ctx, $fh);
 
 	} elsif (not wantarray) {
 		local $/;
 		my $text = <$fh>;
 		try {
-			_cmd_close($fh, $ctx);
+			_cmd_close($ctx, $fh);
 		} catch Git::Error::Command with {
 			# Pepper with the output:
 			my $E = shift;
@@ -288,7 +289,7 @@ sub command {
 		my @lines = <$fh>;
 		defined and chomp for @lines;
 		try {
-			_cmd_close($fh, $ctx);
+			_cmd_close($ctx, $fh);
 		} catch Git::Error::Command with {
 			my $E = shift;
 			$E->{'-outputref'} = \@lines;
@@ -315,7 +316,7 @@ sub command_oneline {
 	my $line = <$fh>;
 	defined $line and chomp $line;
 	try {
-		_cmd_close($fh, $ctx);
+		_cmd_close($ctx, $fh);
 	} catch Git::Error::Command with {
 		# Pepper with the output:
 		my $E = shift;
@@ -383,7 +384,7 @@ have more complicated structure.
 sub command_close_pipe {
 	my ($self, $fh, $ctx) = _maybe_self(@_);
 	$ctx ||= '<unknown>';
-	_cmd_close($fh, $ctx);
+	_cmd_close($ctx, $fh);
 }
 
 =item command_bidi_pipe ( COMMAND [, ARGUMENTS... ] )
@@ -420,7 +421,7 @@ and it is the fourth value returned by C<command_bidi_pipe()>.  The call idiom
 is:
 
 	my ($pid, $in, $out, $ctx) = $r->command_bidi_pipe('cat-file --batch-check');
-	print "000000000\n" $out;
+	print $out "000000000\n";
 	while (<$in>) { ... }
 	$r->command_close_bidi_pipe($pid, $in, $out, $ctx);
 
@@ -428,23 +429,26 @@ Note that you should not rely on whatever actually is in C<CTX>;
 currently it is simply the command name but in future the context might
 have more complicated structure.
 
+C<PIPE_IN> and C<PIPE_OUT> may be C<undef> if they have been closed prior to
+calling this function.  This may be useful in a query-response type of
+commands where caller first writes a query and later reads response, eg:
+
+	my ($pid, $in, $out, $ctx) = $r->command_bidi_pipe('cat-file --batch-check');
+	print $out "000000000\n";
+	close $out;
+	while (<$in>) { ... }
+	$r->command_close_bidi_pipe($pid, $in, undef, $ctx);
+
+This idiom may prevent potential dead locks caused by data sent to the output
+pipe not being flushed and thus not reaching the executed command.
+
 =cut
 
 sub command_close_bidi_pipe {
 	local $?;
-	my ($pid, $in, $out, $ctx) = @_;
-	foreach my $fh ($in, $out) {
-		unless (close $fh) {
-			if ($!) {
-				carp "error closing pipe: $!";
-			} elsif ($? >> 8) {
-				throw Git::Error::Command($ctx, $? >>8);
-			}
-		}
-	}
-
+	my ($self, $pid, $in, $out, $ctx) = _maybe_self(@_);
+	_cmd_close($ctx, (grep { defined } ($in, $out)));
 	waitpid $pid, 0;
-
 	if ($? >> 8) {
 		throw Git::Error::Command($ctx, $? >>8);
 	}
@@ -1020,6 +1024,156 @@ sub _close_cat_blob {
 }
 
 
+=item credential_read( FILEHANDLE )
+
+Reads credential key-value pairs from C<FILEHANDLE>.  Reading stops at EOF or
+when an empty line is encountered.  Each line must be of the form C<key=value>
+with a non-empty key.  Function returns hash with all read values.  Any white
+space (other than new-line character) is preserved.
+
+=cut
+
+sub credential_read {
+	my ($self, $reader) = _maybe_self(@_);
+	my %credential;
+	while (<$reader>) {
+		chomp;
+		if ($_ eq '') {
+			last;
+		} elsif (!/^([^=]+)=(.*)$/) {
+			throw Error::Simple("unable to parse git credential data:\n$_");
+		}
+		$credential{$1} = $2;
+	}
+	return %credential;
+}
+
+=item credential_write( FILEHANDLE, CREDENTIAL_HASHREF )
+
+Writes credential key-value pairs from hash referenced by
+C<CREDENTIAL_HASHREF> to C<FILEHANDLE>.  Keys and values cannot contain
+new-lines or NUL bytes characters, and key cannot contain equal signs nor be
+empty (if they do Error::Simple is thrown).  Any white space is preserved.  If
+value for a key is C<undef>, it will be skipped.
+
+If C<'url'> key exists it will be written first.  (All the other key-value
+pairs are written in sorted order but you should not depend on that).  Once
+all lines are written, an empty line is printed.
+
+=cut
+
+sub credential_write {
+	my ($self, $writer, $credential) = _maybe_self(@_);
+	my ($key, $value);
+
+	# Check if $credential is valid prior to writing anything
+	while (($key, $value) = each %$credential) {
+		if (!defined $key || !length $key) {
+			throw Error::Simple("credential key empty or undefined");
+		} elsif ($key =~ /[=\n\0]/) {
+			throw Error::Simple("credential key contains invalid characters: $key");
+		} elsif (defined $value && $value =~ /[\n\0]/) {
+			throw Error::Simple("credential value for key=$key contains invalid characters: $value");
+		}
+	}
+
+	for $key (sort {
+		# url overwrites other fields, so it must come first
+		return -1 if $a eq 'url';
+		return  1 if $b eq 'url';
+		return $a cmp $b;
+	} keys %$credential) {
+		if (defined $credential->{$key}) {
+			print $writer $key, '=', $credential->{$key}, "\n";
+		}
+	}
+	print $writer "\n";
+}
+
+sub _credential_run {
+	my ($self, $credential, $op) = _maybe_self(@_);
+	my ($pid, $reader, $writer, $ctx) = command_bidi_pipe('credential', $op);
+
+	credential_write $writer, $credential;
+	close $writer;
+
+	if ($op eq "fill") {
+		%$credential = credential_read $reader;
+	}
+	if (<$reader>) {
+		throw Error::Simple("unexpected output from git credential $op response:\n$_\n");
+	}
+
+	command_close_bidi_pipe($pid, $reader, undef, $ctx);
+}
+
+=item credential( CREDENTIAL_HASHREF [, OPERATION ] )
+
+=item credential( CREDENTIAL_HASHREF, CODE )
+
+Executes C<git credential> for a given set of credentials and specified
+operation.  In both forms C<CREDENTIAL_HASHREF> needs to be a reference to
+a hash which stores credentials.  Under certain conditions the hash can
+change.
+
+In the first form, C<OPERATION> can be C<'fill'>, C<'approve'> or C<'reject'>,
+and function will execute corresponding C<git credential> sub-command.  If
+it's omitted C<'fill'> is assumed.  In case of C<'fill'> the values stored in
+C<CREDENTIAL_HASHREF> will be changed to the ones returned by the C<git
+credential fill> command.  The usual usage would look something like:
+
+	my %cred = (
+		'protocol' => 'https',
+		'host' => 'example.com',
+		'username' => 'bob'
+	);
+	Git::credential \%cred;
+	if (try_to_authenticate($cred{'username'}, $cred{'password'})) {
+		Git::credential \%cred, 'approve';
+		... do more stuff ...
+	} else {
+		Git::credential \%cred, 'reject';
+	}
+
+In the second form, C<CODE> needs to be a reference to a subroutine.  The
+function will execute C<git credential fill> to fill the provided credential
+hash, then call C<CODE> with C<CREDENTIAL_HASHREF> as the sole argument.  If
+C<CODE>'s return value is defined, the function will execute C<git credential
+approve> (if return value yields true) or C<git credential reject> (if return
+value is false).  If the return value is undef, nothing at all is executed;
+this is useful, for example, if the credential could neither be verified nor
+rejected due to an unrelated network error.  The return value is the same as
+what C<CODE> returns.  With this form, the usage might look as follows:
+
+	if (Git::credential {
+		'protocol' => 'https',
+		'host' => 'example.com',
+		'username' => 'bob'
+	}, sub {
+		my $cred = shift;
+		return !!try_to_authenticate($cred->{'username'},
+		                             $cred->{'password'});
+	}) {
+		... do more stuff ...
+	}
+
+=cut
+
+sub credential {
+	my ($self, $credential, $op_or_code) = (_maybe_self(@_), 'fill');
+
+	if ('CODE' eq ref $op_or_code) {
+		_credential_run $credential, 'fill';
+		my $ret = $op_or_code->($credential);
+		if (defined $ret) {
+			_credential_run $credential, $ret ? 'approve' : 'reject';
+		}
+		return $ret;
+	} else {
+		_credential_run $credential, $op_or_code;
+	}
+}
+
 { # %TEMP_* Lexical Context
 
 my (%TEMP_FILEMAP, %TEMP_FILES);
@@ -1375,9 +1529,11 @@ sub _execv_git_cmd { exec('git', @_); }
 
 # Close pipe to a subprocess.
 sub _cmd_close {
-	my ($fh, $ctx) = @_;
-	if (not close $fh) {
-		if ($!) {
+	my $ctx = shift @_;
+	foreach my $fh (@_) {
+		if (close $fh) {
+			# nop
+		} elsif ($!) {
 			# It's just close, no point in fatalities
 			carp "error closing pipe: $!";
 		} elsif ($? >> 8) {