native: Fix a possible deadlock in spawn

src/libnative/io/process.rs

@@ -446,13 +446,17 @@ fn spawn_process_os(config: p::ProcessConfig,
         assert_eq!(ret, 0);
     }
 
+    let dirp = dir.map(|p| p.to_c_str());
+    let dirp = dirp.as_ref().map(|c| c.with_ref(|p| p)).unwrap_or(ptr::null());
+
+    with_envp(env, proc(envp) {
+        with_argv(config.program, config.args, proc(argv) unsafe {
             let pipe = os::pipe();
             let mut input = file::FileDesc::new(pipe.input, true);
             let mut output = file::FileDesc::new(pipe.out, true);
 
-    unsafe { set_cloexec(output.fd()) };
+            set_cloexec(output.fd());
 
-    unsafe {
             let pid = fork();
             if pid < 0 {
                 fail!("failure in fork: {}", os::last_os_error());
@@ -551,27 +555,20 @@ fn spawn_process_os(config: p::ProcessConfig,
                 // error, but ignore it anyway.
                 let _ = libc::setsid();
             }
-
-        with_dirp(dir, |dirp| {
             if !dirp.is_null() && chdir(dirp) == -1 {
                 fail(&mut output);
             }
-        });
-
-        with_envp(env, |envp| {
             if !envp.is_null() {
                 set_environ(envp);
             }
-            with_argv(config.program, config.args, |argv| {
             let _ = execvp(*argv, argv);
             fail(&mut output);
         })
     })
 }
-}
 
 #[cfg(unix)]
-fn with_argv<T>(prog: &str, args: &[~str], cb: |**libc::c_char| -> T) -> T {
+fn with_argv<T>(prog: &str, args: &[~str], cb: proc:(**libc::c_char) -> T) -> T {
     use std::slice;
 
     // We can't directly convert `str`s into `*char`s, as someone needs to hold
@@ -597,7 +594,7 @@ fn with_argv<T>(prog: &str, args: &[~str], cb: |**libc::c_char| -> T) -> T {
 }
 
 #[cfg(unix)]
-fn with_envp<T>(env: Option<~[(~str, ~str)]>, cb: |*c_void| -> T) -> T {
+fn with_envp<T>(env: Option<~[(~str, ~str)]>, cb: proc:(*c_void) -> T) -> T {
     use std::slice;
 
     // On posixy systems we can pass a char** for envp, which is a
@@ -645,6 +642,7 @@ fn with_envp<T>(env: Option<~[(~str, ~str)]>, cb: |*mut c_void| -> T) -> T {
     }
 }
 
+#[cfg(windows)]
 fn with_dirp<T>(d: Option<&Path>, cb: |*libc::c_char| -> T) -> T {
     match d {
       Some(dir) => dir.with_c_str(|buf| cb(buf)),