| 1 | //! Subshell execution |
| 2 | //! |
| 3 | //! Subshells execute commands in a subprocess, providing isolation: |
| 4 | //! - Variable changes don't affect the parent shell |
| 5 | //! - Directory changes (cd) don't affect the parent |
| 6 | //! - `exit` terminates the subshell, not the parent |
| 7 | |
| 8 | use rush_expand::Context; |
| 9 | use rush_parser::ast::Subshell; |
| 10 | use crate::command::ExecutionResult; |
| 11 | |
| 12 | /// Execute commands in a subshell (subprocess) |
| 13 | /// |
| 14 | /// Syntax: (command; command; ...) |
| 15 | /// |
| 16 | /// The commands run in a forked child process, so any state changes |
| 17 | /// (variables, working directory, etc.) are isolated from the parent shell. |
| 18 | #[cfg(unix)] |
| 19 | pub fn execute_subshell( |
| 20 | subshell: &Subshell, |
| 21 | context: &mut Context, |
| 22 | ) -> Result<ExecutionResult, String> { |
| 23 | use nix::sys::wait::{waitpid, WaitStatus}; |
| 24 | use nix::unistd::{fork, ForkResult}; |
| 25 | use std::process; |
| 26 | |
| 27 | // Fork the process |
| 28 | match unsafe { fork() } { |
| 29 | Ok(ForkResult::Child) => { |
| 30 | // Child process: execute the commands |
| 31 | let exit_code = execute_subshell_child(&subshell.commands, context); |
| 32 | process::exit(exit_code); |
| 33 | } |
| 34 | Ok(ForkResult::Parent { child }) => { |
| 35 | // Parent process: wait for child to complete |
| 36 | match waitpid(child, None) { |
| 37 | Ok(WaitStatus::Exited(_, exit_code)) => { |
| 38 | // Child exited normally |
| 39 | Ok(crate::command::exit_code_to_result(exit_code)) |
| 40 | } |
| 41 | Ok(WaitStatus::Signaled(_, signal, _)) => { |
| 42 | // Child was killed by a signal |
| 43 | // Return 128 + signal number (bash convention) |
| 44 | Ok(crate::command::exit_code_to_result(128 + signal as i32)) |
| 45 | } |
| 46 | Ok(_) => { |
| 47 | // Other wait status (stopped, continued, etc.) |
| 48 | Ok(crate::command::exit_code_to_result(1)) |
| 49 | } |
| 50 | Err(e) => { |
| 51 | Err(format!("Failed to wait for subshell: {}", e)) |
| 52 | } |
| 53 | } |
| 54 | } |
| 55 | Err(e) => { |
| 56 | Err(format!("Failed to fork for subshell: {}", e)) |
| 57 | } |
| 58 | } |
| 59 | } |
| 60 | |
| 61 | /// Execute commands in the child process |
| 62 | /// Returns the exit code to use for process::exit() |
| 63 | #[cfg(unix)] |
| 64 | pub(crate) fn execute_subshell_child( |
| 65 | commands: &[rush_parser::CompleteCommand], |
| 66 | context: &mut Context, |
| 67 | ) -> i32 { |
| 68 | let mut last_exit_code = 0; |
| 69 | |
| 70 | for cmd in commands { |
| 71 | match crate::control_flow::execute_complete_command(cmd, context) { |
| 72 | Ok(result) => { |
| 73 | last_exit_code = result.exit_code(); |
| 74 | context.set_exit_status(last_exit_code); |
| 75 | } |
| 76 | Err(e) => { |
| 77 | eprintln!("rush: {}", e); |
| 78 | return 1; |
| 79 | } |
| 80 | } |
| 81 | } |
| 82 | |
| 83 | last_exit_code |
| 84 | } |
| 85 | |
| 86 | /// Execute a subshell in the background |
| 87 | /// Returns (pid, pgid, command_string) |
| 88 | #[cfg(unix)] |
| 89 | pub fn execute_subshell_background( |
| 90 | subshell: &Subshell, |
| 91 | context: &mut Context, |
| 92 | ) -> Result<(nix::unistd::Pid, nix::unistd::Pid, String), String> { |
| 93 | use nix::unistd::{fork, ForkResult, setpgid, Pid}; |
| 94 | |
| 95 | // Build a command string for display |
| 96 | let command_string = format!("(subshell with {} commands)", subshell.commands.len()); |
| 97 | |
| 98 | // Fork the process |
| 99 | match unsafe { fork() } { |
| 100 | Ok(ForkResult::Child) => { |
| 101 | // Child process: create new process group and execute |
| 102 | let pid = std::process::id() as i32; |
| 103 | let _ = setpgid(Pid::from_raw(pid), Pid::from_raw(pid)); |
| 104 | |
| 105 | let exit_code = execute_subshell_child(&subshell.commands, context); |
| 106 | std::process::exit(exit_code); |
| 107 | } |
| 108 | Ok(ForkResult::Parent { child }) => { |
| 109 | // Create new process group for the child |
| 110 | let _ = setpgid(child, child); |
| 111 | |
| 112 | // Don't wait - that's what makes it background |
| 113 | Ok((child, child, command_string)) |
| 114 | } |
| 115 | Err(e) => { |
| 116 | Err(format!("Failed to fork for background subshell: {}", e)) |
| 117 | } |
| 118 | } |
| 119 | } |
| 120 | |
| 121 | /// Fallback for non-Unix platforms |
| 122 | #[cfg(not(unix))] |
| 123 | pub fn execute_subshell( |
| 124 | _subshell: &Subshell, |
| 125 | _context: &mut Context, |
| 126 | ) -> Result<ExecutionResult, String> { |
| 127 | Err("Subshells are not supported on this platform".to_string()) |
| 128 | } |
| 129 | |
| 130 | #[cfg(not(unix))] |
| 131 | pub fn execute_subshell_background( |
| 132 | _subshell: &Subshell, |
| 133 | _context: &mut Context, |
| 134 | ) -> Result<(i32, i32, String), String> { |
| 135 | Err("Background subshells are not supported on this platform".to_string()) |
| 136 | } |
| 137 |