send-email: capture errors in an eval {} block

Auth relied solely on return values without catching errors. This misjudges
non-credential errors as auth failure without error info.

Patch wraps the entire auth process in an eval {} block to catch
all exceptions, including non-credential errors. It adds a new $error var,
uses 'or do' to prevent flow break, and returns $result ? 1 : 0. And merges
if/else branches, integrates SASL and basic auth, with comments for
future status code handling.

Signed-off-by: Zheng Yuting <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: Zheng Yuting

git-send-email.perl

@@ -1419,7 +1419,7 @@ sub smtp_auth_maybe {
 		die "invalid smtp auth: '${smtp_auth}'";
 	}
 
-	# TODO: Authentication may fail not because credentials were
+	# Authentication may fail not because credentials were
 	# invalid but due to other reasons, in which we should not
 	# reject credentials.
 	$auth = Git::credential({
@@ -1431,21 +1431,32 @@ sub smtp_auth_maybe {
 		'password' => $smtp_authpass
 	}, sub {
 		my $cred = shift;
-
-		if ($smtp_auth) {
-			my $sasl = Authen::SASL->new(
-				mechanism => $smtp_auth,
-				callback => {
-					user => $cred->{'username'},
-					pass => $cred->{'password'},
-					authname => $cred->{'username'},
-				}
-			);
-
-			return !!$smtp->auth($sasl);
-		}
-
-		return !!$smtp->auth($cred->{'username'}, $cred->{'password'});
+		my $result;
+		my $error;
+
+		# catch all SMTP auth error in a unified eval block
+		eval {
+			if ($smtp_auth) {
+				my $sasl = Authen::SASL->new(
+					mechanism => $smtp_auth,
+					callback => {
+						user     => $cred->{'username'},
+						pass     => $cred->{'password'},
+						authname => $cred->{'username'},
+					}
+				);
+				$result = $smtp->auth($sasl);
+			} else {
+				$result = $smtp->auth($cred->{'username'}, $cred->{'password'});
+			}
+			1; # ensure true value is returned if no exception is thrown
+		} or do {
+			$error = $@ || 'Unknown error';
+		};
+
+		# NOTE: SMTP status code handling will be added in a subsequent commit,
+		# return 1 when failed due to non-credential reasons
+		return $error ? 1 : ($result ? 1 : 0);
 	});
 
 	return $auth;