Shell: Place Pipe redirections at the beginning of the redirection list

This makes commands like `foo 2>&1 | bar` behave as expected (which is
to pipe both stdout and stderr of `foo` to stdin of `bar`).
Previously, this would've piped stderr of `foo` into stdout, and the
stdout of `foo` into the stdin of `bar`.

Userland/Shell/AST.cpp

@@ -2220,8 +2220,27 @@ RefPtr<Value> Pipe::run(RefPtr<Shell> shell)
 
  auto pipe_read_end = FdRedirection::create(-1, STDIN_FILENO, Rewiring::Close::Old);
  auto pipe_write_end = FdRedirection::create(-1, STDOUT_FILENO, pipe_read_end, Rewiring::Close::RefreshOld);
- first_in_right.redirections.append(pipe_read_end);
- last_in_left.redirections.append(pipe_write_end);
+
+ auto insert_at_start_or_after_last_pipe = [&](auto& pipe, auto& command) {
+ size_t insert_index = 0;
+ auto& redirections = command.redirections;
+ for (ssize_t i = redirections.size() - 1; i >= 0; --i) {
+ auto& redirection = redirections[i];
+ if (!redirection.is_fd_redirection())
+ continue;
+ auto& fd_redirection = static_cast<FdRedirection&>(redirection);
+ if (fd_redirection.old_fd == -1) {
+ insert_index = i;
+ break;
+ }
+ }
+
+ redirections.insert(insert_index, pipe);
+ };
+
+ insert_at_start_or_after_last_pipe(pipe_read_end, first_in_right);
+ insert_at_start_or_after_last_pipe(pipe_write_end, last_in_left);
+
  last_in_left.should_wait = false;
  last_in_left.is_pipe_source = true;