feat: add rsync old-args compatibility mode

tests/test_transport_ssh.c

@@ -4,13 +4,13 @@
 
 static void test_ssh_connect_invalid_dest_no_colon() {
   /* cppcheck-suppress constVariablePointer */
-  Client* client = client_connect_ssh("invalid-destination-no-colon", 22, NULL);
+  Client* client = client_connect_ssh("invalid-destination-no-colon", 22, NULL, false);
   EXPECT_NULL(client);
 }
 
 static void test_ssh_connect_invalid_dest_empty() {
   /* cppcheck-suppress constVariablePointer */
-  Client* client = client_connect_ssh("", 22, NULL);
+  Client* client = client_connect_ssh("", 22, NULL, false);
   EXPECT_NULL(client);
 }
 
@@ -18,7 +18,7 @@ static void test_ssh_connect_invalid_dest_empty() {
  * parse_remote_dest succeeds, ssh is exec'd and fails, but the function
  * creates a Client that must be cleaned up. */
 static void test_ssh_connect_malformed() {
-  Client* client = client_connect_ssh(":", 22, NULL);
+  Client* client = client_connect_ssh(":", 22, NULL, false);
   /* ssh binary exists, so exec succeeds; the function returns a Client.
    * We just verify it doesn't crash and clean up properly. */
   if (client != NULL) {
@@ -31,7 +31,7 @@ static void test_ssh_connect_malformed() {
 /* Test client_connect_ssh with valid format but unreachable host.
  * The function launches ssh which will fail to connect, returns a Client. */
 static void test_ssh_connect_unreachable() {
-  Client* client = client_connect_ssh("nonexistent.invalid:/remote/path", 22, NULL);
+  Client* client = client_connect_ssh("nonexistent.invalid:/remote/path", 22, NULL, false);
   if (client != NULL) {
     client_disconnect(client);
     client_delete(client);
@@ -39,9 +39,24 @@ static void test_ssh_connect_unreachable() {
   EXPECT_TRUE(true);
 }
 
+static void test_ssh_remote_command_argument_modes() {
+  char* command = ssh_build_remote_command("fast sync; touch /tmp/pwned", false);
+  EXPECT_EQ_STR(command, "'fast sync; touch /tmp/pwned' --stdio");
+  free(command);
+
+  command = ssh_build_remote_command("fast'sync", false);
+  EXPECT_EQ_STR(command, "'fast'\\''sync' --stdio");
+  free(command);
+
+  command = ssh_build_remote_command("fast sync; touch /tmp/pwned", true);
+  EXPECT_EQ_STR(command, "fast sync; touch /tmp/pwned --stdio");
+  free(command);
+}
+
 void test_transport_ssh() {
   test_ssh_connect_invalid_dest_no_colon();
   test_ssh_connect_invalid_dest_empty();
   test_ssh_connect_malformed();
   test_ssh_connect_unreachable();
+  test_ssh_remote_command_argument_modes();
 }