diff --git a/library/std/src/process/tests.rs b/library/std/src/process/tests.rs index 88cc95caf4073..fb0b495961c36 100644 --- a/library/std/src/process/tests.rs +++ b/library/std/src/process/tests.rs @@ -96,9 +96,23 @@ fn stdout_works() { #[test] #[cfg_attr(any(windows, target_os = "vxworks"), ignore)] fn set_current_dir_works() { + // On many Unix platforms this will use the posix_spawn path. let mut cmd = shell_cmd(); cmd.arg("-c").arg("pwd").current_dir("/").stdout(Stdio::piped()); assert_eq!(run_output(cmd), "/\n"); + + // Also test the fork/exec path by setting a pre_exec function. + #[cfg(unix)] + { + use crate::os::unix::process::CommandExt; + + let mut cmd = shell_cmd(); + cmd.arg("-c").arg("pwd").current_dir("/").stdout(Stdio::piped()); + unsafe { + cmd.pre_exec(|| Ok(())); + } + assert_eq!(run_output(cmd), "/\n"); + } } #[test] diff --git a/library/std/src/sys/pal/unix/process/process_unix.rs b/library/std/src/sys/pal/unix/process/process_unix.rs index 4551d49e841f7..8faf1fda5464d 100644 --- a/library/std/src/sys/pal/unix/process/process_unix.rs +++ b/library/std/src/sys/pal/unix/process/process_unix.rs @@ -448,7 +448,6 @@ impl Command { use core::sync::atomic::{AtomicU8, Ordering}; use crate::mem::MaybeUninit; - use crate::sys::weak::weak; use crate::sys::{self, cvt_nz, on_broken_pipe_flag_used}; if self.get_gid().is_some() @@ -462,6 +461,8 @@ impl Command { cfg_if::cfg_if! { if #[cfg(target_os = "linux")] { + use crate::sys::weak::weak; + weak! { fn pidfd_spawnp( *mut libc::c_int, @@ -575,16 +576,44 @@ impl Command { } } - // Solaris, glibc 2.29+, and musl 1.24+ can set a new working directory, - // and maybe others will gain this non-POSIX function too. We'll check - // for this weak symbol as soon as it's needed, so we can return early - // otherwise to do a manual chdir before exec. - weak! { - fn posix_spawn_file_actions_addchdir_np( - *mut libc::posix_spawn_file_actions_t, - *const libc::c_char - ) -> libc::c_int + type PosixSpawnAddChdirFn = unsafe extern "C" fn( + *mut libc::posix_spawn_file_actions_t, + *const libc::c_char, + ) -> libc::c_int; + + /// Get the function pointer for adding a chdir action to a + /// `posix_spawn_file_actions_t`, if available, assuming a dynamic libc. + /// + /// Some platforms can set a new working directory for a spawned process in the + /// `posix_spawn` path. This function looks up the function pointer for adding + /// such an action to a `posix_spawn_file_actions_t` struct. + #[cfg(not(all(target_os = "linux", target_env = "musl")))] + fn get_posix_spawn_addchdir() -> Option { + use crate::sys::weak::weak; + + weak! { + fn posix_spawn_file_actions_addchdir_np( + *mut libc::posix_spawn_file_actions_t, + *const libc::c_char + ) -> libc::c_int + } + + posix_spawn_file_actions_addchdir_np.get() + } + + /// Get the function pointer for adding a chdir action to a + /// `posix_spawn_file_actions_t`, if available, on platforms where the function + /// is known to exist. + /// + /// Weak symbol lookup doesn't work with statically linked libcs, so in cases + /// where static linking is possible we need to either check for the presence + /// of the symbol at compile time or know about it upfront. + #[cfg(all(target_os = "linux", target_env = "musl"))] + fn get_posix_spawn_addchdir() -> Option { + // Our minimum required musl supports this function, so we can just use it. + Some(libc::posix_spawn_file_actions_addchdir_np) } + let addchdir = match self.get_cwd() { Some(cwd) => { if cfg!(target_vendor = "apple") { @@ -597,7 +626,10 @@ impl Command { return Ok(None); } } - match posix_spawn_file_actions_addchdir_np.get() { + // Check for the availability of the posix_spawn addchdir + // function now. If it isn't available, bail and use the + // fork/exec path. + match get_posix_spawn_addchdir() { Some(f) => Some((f, cwd)), None => return Ok(None), }