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| 1 | +//! RustPython venv launcher |
| 2 | +//! |
| 3 | +//! A lightweight launcher that reads pyvenv.cfg and delegates execution |
| 4 | +//! to the actual Python interpreter. This mimics CPython's venvlauncher.c. |
| 5 | +//! Windows only. |
| 6 | +
|
| 7 | +#[cfg(not(windows))] |
| 8 | +compile_error!("venvlauncher is only supported on Windows"); |
| 9 | + |
| 10 | +use std::env; |
| 11 | +use std::fs; |
| 12 | +use std::path::{Path, PathBuf}; |
| 13 | +use std::process::ExitCode; |
| 14 | + |
| 15 | +fn main() -> ExitCode { |
| 16 | + match run() { |
| 17 | + Ok(code) => ExitCode::from(code as u8), |
| 18 | + Err(e) => { |
| 19 | + eprintln!("venvlauncher error: {}", e); |
| 20 | + ExitCode::from(1) |
| 21 | + } |
| 22 | + } |
| 23 | +} |
| 24 | + |
| 25 | +fn run() -> Result<u32, Box<dyn std::error::Error>> { |
| 26 | + // 1. Get own executable path |
| 27 | + let exe_path = env::current_exe()?; |
| 28 | + let exe_name = exe_path |
| 29 | + .file_name() |
| 30 | + .ok_or("Failed to get executable name")? |
| 31 | + .to_string_lossy(); |
| 32 | + |
| 33 | + // 2. Determine target executable name based on launcher name |
| 34 | + // pythonw.exe / venvwlauncher -> pythonw.exe (GUI, no console) |
| 35 | + // python.exe / venvlauncher -> python.exe (console) |
| 36 | + let exe_name_lower = exe_name.to_lowercase(); |
| 37 | + let target_exe = if exe_name_lower.contains("pythonw") || exe_name_lower.contains("venvw") { |
| 38 | + "pythonw.exe" |
| 39 | + } else { |
| 40 | + "python.exe" |
| 41 | + }; |
| 42 | + |
| 43 | + // 3. Find pyvenv.cfg |
| 44 | + // The launcher is in Scripts/ directory, pyvenv.cfg is in parent (venv root) |
| 45 | + let scripts_dir = exe_path.parent().ok_or("Failed to get Scripts directory")?; |
| 46 | + let venv_dir = scripts_dir.parent().ok_or("Failed to get venv directory")?; |
| 47 | + let cfg_path = venv_dir.join("pyvenv.cfg"); |
| 48 | + |
| 49 | + if !cfg_path.exists() { |
| 50 | + return Err(format!("pyvenv.cfg not found: {}", cfg_path.display()).into()); |
| 51 | + } |
| 52 | + |
| 53 | + // 4. Parse home= from pyvenv.cfg |
| 54 | + let home = read_home(&cfg_path)?; |
| 55 | + |
| 56 | + // 5. Locate python executable in home directory |
| 57 | + let python_path = PathBuf::from(&home).join(target_exe); |
| 58 | + if !python_path.exists() { |
| 59 | + return Err(format!("Python not found: {}", python_path.display()).into()); |
| 60 | + } |
| 61 | + |
| 62 | + // 6. Set __PYVENV_LAUNCHER__ environment variable |
| 63 | + // This tells Python it was launched from a venv |
| 64 | + // SAFETY: We are in a single-threaded context (program entry point) |
| 65 | + unsafe { |
| 66 | + env::set_var("__PYVENV_LAUNCHER__", &exe_path); |
| 67 | + } |
| 68 | + |
| 69 | + // 7. Launch Python with same arguments |
| 70 | + let args: Vec<String> = env::args().skip(1).collect(); |
| 71 | + launch_process(&python_path, &args) |
| 72 | +} |
| 73 | + |
| 74 | +/// Parse the `home=` value from pyvenv.cfg |
| 75 | +fn read_home(cfg_path: &Path) -> Result<String, Box<dyn std::error::Error>> { |
| 76 | + let content = fs::read_to_string(cfg_path)?; |
| 77 | + |
| 78 | + for line in content.lines() { |
| 79 | + let line = line.trim(); |
| 80 | + // Skip comments and empty lines |
| 81 | + if line.is_empty() || line.starts_with('#') { |
| 82 | + continue; |
| 83 | + } |
| 84 | + |
| 85 | + // Look for "home = <path>" or "home=<path>" |
| 86 | + if let Some(rest) = line.strip_prefix("home") { |
| 87 | + let rest = rest.trim_start(); |
| 88 | + if let Some(value) = rest.strip_prefix('=') { |
| 89 | + return Ok(value.trim().to_string()); |
| 90 | + } |
| 91 | + } |
| 92 | + } |
| 93 | + |
| 94 | + Err("'home' key not found in pyvenv.cfg".into()) |
| 95 | +} |
| 96 | + |
| 97 | +/// Launch the Python process and wait for it to complete |
| 98 | +fn launch_process(exe: &Path, args: &[String]) -> Result<u32, Box<dyn std::error::Error>> { |
| 99 | + use std::process::Command; |
| 100 | + |
| 101 | + let status = Command::new(exe).args(args).status()?; |
| 102 | + |
| 103 | + Ok(status.code().unwrap_or(1) as u32) |
| 104 | +} |
| 105 | + |
| 106 | +#[cfg(all(test, windows))] |
| 107 | +mod tests { |
| 108 | + use super::*; |
| 109 | + use std::io::Write; |
| 110 | + |
| 111 | + #[test] |
| 112 | + fn test_read_home() { |
| 113 | + let temp_dir = std::env::temp_dir(); |
| 114 | + let cfg_path = temp_dir.join("test_pyvenv.cfg"); |
| 115 | + |
| 116 | + let mut file = fs::File::create(&cfg_path).unwrap(); |
| 117 | + writeln!(file, "home = C:\\Python313").unwrap(); |
| 118 | + writeln!(file, "include-system-site-packages = false").unwrap(); |
| 119 | + writeln!(file, "version = 3.13.0").unwrap(); |
| 120 | + |
| 121 | + let home = read_home(&cfg_path).unwrap(); |
| 122 | + assert_eq!(home, "C:\\Python313"); |
| 123 | + |
| 124 | + fs::remove_file(&cfg_path).unwrap(); |
| 125 | + } |
| 126 | + |
| 127 | + #[test] |
| 128 | + fn test_read_home_no_spaces() { |
| 129 | + let temp_dir = std::env::temp_dir(); |
| 130 | + let cfg_path = temp_dir.join("test_pyvenv2.cfg"); |
| 131 | + |
| 132 | + let mut file = fs::File::create(&cfg_path).unwrap(); |
| 133 | + writeln!(file, "home=C:\\Python313").unwrap(); |
| 134 | + |
| 135 | + let home = read_home(&cfg_path).unwrap(); |
| 136 | + assert_eq!(home, "C:\\Python313"); |
| 137 | + |
| 138 | + fs::remove_file(&cfg_path).unwrap(); |
| 139 | + } |
| 140 | + |
| 141 | + #[test] |
| 142 | + fn test_read_home_with_comments() { |
| 143 | + let temp_dir = std::env::temp_dir(); |
| 144 | + let cfg_path = temp_dir.join("test_pyvenv3.cfg"); |
| 145 | + |
| 146 | + let mut file = fs::File::create(&cfg_path).unwrap(); |
| 147 | + writeln!(file, "# This is a comment").unwrap(); |
| 148 | + writeln!(file, "home = D:\\RustPython").unwrap(); |
| 149 | + |
| 150 | + let home = read_home(&cfg_path).unwrap(); |
| 151 | + assert_eq!(home, "D:\\RustPython"); |
| 152 | + |
| 153 | + fs::remove_file(&cfg_path).unwrap(); |
| 154 | + } |
| 155 | +} |
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