Fixes #55775 -- fixed regression in Command::exec's handling of PATH.

This restores the previous behavior where if env_clear() or env_remove("PATH") was used we fall back to a default PATH of "/bin:/usr/bin"

Author: Alex Gaynor

src/libstd/sys/unix/process/process_unix.rs

@@ -135,14 +135,15 @@ impl Command {
  Some(envp) => {
  match envp.get_items().iter().find(|var| var.as_bytes().starts_with(b"PATH=")) {
  Some(p) => &p.as_bytes()[5..],
- None => return None,
+ // Chosen to match what glibc does if there's no PATH variable
+ None => b"/bin:/usr/bin",
  }
  },
  // maybe_envp is None if the process isn't changing the parent's env at all.
  None => {
  match parent_path.as_ref() {
  Some(p) => p.as_bytes(),
- None => return None,
+ None => b"/bin:/usr/bin",
  }
  },
  };

src/test/run-pass/command-exec.rs

@@ -55,6 +55,16 @@ fn main() {
  println!("passed");
  }
 
+ "exec-test6" => {
+ let err = Command::new("echo").arg("passed").env_clear().exec();
+ panic!("failed to spawn: {}", err);
+ }
+
+ "exec-test7" => {
+ let err = Command::new("echo").arg("passed").env_remove("PATH").exec();
+ panic!("failed to spawn: {}", err);
+ }
+
  _ => panic!("unknown argument: {}", arg),
  }
  return
@@ -84,4 +94,14 @@ fn main() {
  assert!(output.status.success());
  assert!(output.stderr.is_empty());
  assert_eq!(output.stdout, b"passed\n");
+
+ let output = Command::new(&me).arg("exec-test6").output().unwrap();
+ assert!(output.status.success());
+ assert!(output.stderr.is_empty());
+ assert_eq!(output.stdout, b"passed\n");
+
+ let output = Command::new(&me).arg("exec-test7").output().unwrap();
+ assert!(output.status.success());
+ assert!(output.stderr.is_empty());
+ assert_eq!(output.stdout, b"passed\n");
 }