std: Add an unstable method Child::id

This commits adds a method to the `std::process` module to get the process
identifier of the child as a `u32`. On Windows the underlying identifier is
already a `u32`, and on Unix the type is typically defined as `c_int` (`i32` for
almost all our supported platforms), but the actually pid is normally a small
positive number.

Eventually we may add functions to load information about a process based on its
identifier or the ability to terminate a process based on its identifier, but
for now this function should enable this sort of functionality to exist outside
the standard library.

1 files changed, 1 insertions, 0 deletions

diff --git a/src/libstd/sys/windows/c.rs b/src/libstd/sys/windows/c.rs
index b07d063de45..e9b850856e1 100644
--- a/src/libstd/sys/windows/c.rs
+++ b/src/libstd/sys/windows/c.rs
@@ -482,6 +482,7 @@ extern "system" {
                                dwMilliseconds: libc::DWORD) -> libc::DWORD;
     pub fn SwitchToThread() -> libc::BOOL;
     pub fn Sleep(dwMilliseconds: libc::DWORD);
+    pub fn GetProcessId(handle: libc::HANDLE) -> libc::DWORD;
 }
 
 #[link(name = "userenv")]