Process spawning via PATH is different on unix than it is on windows

[alexcrichton]

Due to the separate fork + exec steps on unix, the following test case passes on unix. On windows, however, the "atomic" fork + exec causes the test to fail.

Notably, on unix the child's PATH environment variable is used to lookup the program to execute, whereas on windows it uses the parent's PATH variable.

use std::os;
use std::io::{File, TempDir, Command, util, UserRWX, fs};

fn main() {
    let args = os::args();
    if args.len() > 1 && args.get(1).as_slice() == "child" {
        return assert_eq!(args.get(0).as_slice(), "mytest");
    }

    let dir = TempDir::new("mytest").unwrap();
    let me = os::self_exe_name().unwrap();
    let dest = dir.path().join("mytest");
    util::copy(&mut File::open(&me), &mut File::create(&dest)).unwrap();
    fs::chmod(&dest, UserRWX).unwrap();

    Command::new("mytest").env(&[("PATH".to_string(),
                                  dir.path().as_str().unwrap().to_string())])
                          .arg("child")
                          .spawn().unwrap();
}

The behavior of the two platforms needs to be consistent, and I believe that the unix behavior is what one would expect.

[alexcrichton]

Note that the test is just copying itself to a temporary directory and then running it from the temporary directory via PATH (cutting through the irrelevant bits)

[wycats]

The Unix behavior sounds right to me.

[alexcrichton]

I have a proposed fix with libuv to fix the libgreen side of things: joyent/libuv#1337