Auto merge of #77717 - tmiasko:posix-spawn-error-check, r=cuviper

Fix error checking in posix_spawn implementation of Command

* Check for errors returned from posix_spawn*_init functions
* Check for non-zero return value from posix_spawn functions

Author: bors

library/std/src/sys/unix/process/process_unix.rs

@@ -319,79 +319,85 @@ impl Command {
 
         let mut p = Process { pid: 0, status: None };
 
-        struct PosixSpawnFileActions(MaybeUninit<libc::posix_spawn_file_actions_t>);
+        struct PosixSpawnFileActions<'a>(&'a mut MaybeUninit<libc::posix_spawn_file_actions_t>);
 
-        impl Drop for PosixSpawnFileActions {
+        impl Drop for PosixSpawnFileActions<'_> {
             fn drop(&mut self) {
                 unsafe {
                     libc::posix_spawn_file_actions_destroy(self.0.as_mut_ptr());
                 }
             }
         }
 
-        struct PosixSpawnattr(MaybeUninit<libc::posix_spawnattr_t>);
+        struct PosixSpawnattr<'a>(&'a mut MaybeUninit<libc::posix_spawnattr_t>);
 
-        impl Drop for PosixSpawnattr {
+        impl Drop for PosixSpawnattr<'_> {
             fn drop(&mut self) {
                 unsafe {
                     libc::posix_spawnattr_destroy(self.0.as_mut_ptr());
                 }
             }
         }
 
+        fn cvt_nz(error: libc::c_int) -> io::Result<()> {
+            if error == 0 { Ok(()) } else { Err(io::Error::from_raw_os_error(error)) }
+        }
+
         unsafe {
-            let mut file_actions = PosixSpawnFileActions(MaybeUninit::uninit());
-            let mut attrs = PosixSpawnattr(MaybeUninit::uninit());
+            let mut attrs = MaybeUninit::uninit();
+            cvt_nz(libc::posix_spawnattr_init(attrs.as_mut_ptr()))?;
+            let attrs = PosixSpawnattr(&mut attrs);
 
-            libc::posix_spawnattr_init(attrs.0.as_mut_ptr());
-            libc::posix_spawn_file_actions_init(file_actions.0.as_mut_ptr());
+            let mut file_actions = MaybeUninit::uninit();
+            cvt_nz(libc::posix_spawn_file_actions_init(file_actions.as_mut_ptr()))?;
+            let file_actions = PosixSpawnFileActions(&mut file_actions);
 
             if let Some(fd) = stdio.stdin.fd() {
-                cvt(libc::posix_spawn_file_actions_adddup2(
+                cvt_nz(libc::posix_spawn_file_actions_adddup2(
                     file_actions.0.as_mut_ptr(),
                     fd,
                     libc::STDIN_FILENO,
                 ))?;
             }
             if let Some(fd) = stdio.stdout.fd() {
-                cvt(libc::posix_spawn_file_actions_adddup2(
+                cvt_nz(libc::posix_spawn_file_actions_adddup2(
                     file_actions.0.as_mut_ptr(),
                     fd,
                     libc::STDOUT_FILENO,
                 ))?;
             }
             if let Some(fd) = stdio.stderr.fd() {
-                cvt(libc::posix_spawn_file_actions_adddup2(
+                cvt_nz(libc::posix_spawn_file_actions_adddup2(
                     file_actions.0.as_mut_ptr(),
                     fd,
                     libc::STDERR_FILENO,
                 ))?;
             }
             if let Some((f, cwd)) = addchdir {
-                cvt(f(file_actions.0.as_mut_ptr(), cwd.as_ptr()))?;
+                cvt_nz(f(file_actions.0.as_mut_ptr(), cwd.as_ptr()))?;
             }
 
             let mut set = MaybeUninit::<libc::sigset_t>::uninit();
             cvt(sigemptyset(set.as_mut_ptr()))?;
-            cvt(libc::posix_spawnattr_setsigmask(attrs.0.as_mut_ptr(), set.as_ptr()))?;
+            cvt_nz(libc::posix_spawnattr_setsigmask(attrs.0.as_mut_ptr(), set.as_ptr()))?;
             cvt(sigaddset(set.as_mut_ptr(), libc::SIGPIPE))?;
-            cvt(libc::posix_spawnattr_setsigdefault(attrs.0.as_mut_ptr(), set.as_ptr()))?;
+            cvt_nz(libc::posix_spawnattr_setsigdefault(attrs.0.as_mut_ptr(), set.as_ptr()))?;
 
             let flags = libc::POSIX_SPAWN_SETSIGDEF | libc::POSIX_SPAWN_SETSIGMASK;
-            cvt(libc::posix_spawnattr_setflags(attrs.0.as_mut_ptr(), flags as _))?;
+            cvt_nz(libc::posix_spawnattr_setflags(attrs.0.as_mut_ptr(), flags as _))?;
 
             // Make sure we synchronize access to the global `environ` resource
             let _env_lock = sys::os::env_lock();
             let envp = envp.map(|c| c.as_ptr()).unwrap_or_else(|| *sys::os::environ() as *const _);
-            let ret = libc::posix_spawnp(
+            cvt_nz(libc::posix_spawnp(
                 &mut p.pid,
                 self.get_program_cstr().as_ptr(),
                 file_actions.0.as_ptr(),
                 attrs.0.as_ptr(),
                 self.get_argv().as_ptr() as *const _,
                 envp as *const _,
-            );
-            if ret == 0 { Ok(Some(p)) } else { Err(io::Error::from_raw_os_error(ret)) }
+            ))?;
+            Ok(Some(p))
         }
     }
 }