From 09fa2827ff84bb77216be0a76cd784f27dbdb076 Mon Sep 17 00:00:00 2001
From: Alexander Belopolsky <a@enlnt.com>
Date: Mon, 9 Oct 2017 12:09:44 -0400
Subject: [PATCH] Implemented `getpid(p::Process)`.

Closes # 4752.
---
 base/process.jl | 14 ++++++++++++++
 src/jl_uv.c     |  1 +
 test/spawn.jl   | 10 ++++++++++
 3 files changed, 25 insertions(+)

diff --git a/base/process.jl b/base/process.jl
index cc188a084e6752..b531d86d07bcb6 100644
--- a/base/process.jl
+++ b/base/process.jl
@@ -335,6 +335,20 @@ end
 pipe_reader(p::Process) = p.out
 pipe_writer(p::Process) = p.in
 
+"""
+    getpid(p::Process) -> Int32
+
+Get the process ID of a running process. Returns `-1` if the
+process is not running.
+"""
+function Base.getpid(p::Process)
+    if p.handle != C_NULL
+        ccall(:jl_uv_process_pid, Cint, (Ptr{Void},), p.handle)
+    else
+        Cint(-1)
+    end
+end
+
 struct ProcessChain <: AbstractPipe
     processes::Vector{Process}
     in::Redirectable
diff --git a/src/jl_uv.c b/src/jl_uv.c
index 77719693eb943e..66399bd2c72468 100644
--- a/src/jl_uv.c
+++ b/src/jl_uv.c
@@ -112,6 +112,7 @@ static void jl_uv_shutdownCallback(uv_shutdown_t *req, int status)
 }
 
 // getters and setters
+JL_DLLEXPORT int jl_uv_process_pid(uv_process_t *p) { return p->pid; }
 JL_DLLEXPORT void *jl_uv_process_data(uv_process_t *p) { return p->data; }
 JL_DLLEXPORT void *jl_uv_buf_base(const uv_buf_t *buf) { return buf->base; }
 JL_DLLEXPORT size_t jl_uv_buf_len(const uv_buf_t *buf) { return buf->len; }
diff --git a/test/spawn.jl b/test/spawn.jl
index 3ebeb130ab500d..7202c82a0d8de7 100644
--- a/test/spawn.jl
+++ b/test/spawn.jl
@@ -220,6 +220,16 @@ if valgrind_off
     @test success(proc)
 end
 
+# issue #4752
+let out = Pipe(), proc, pid
+    proc = spawn(pipeline(`$exename --startup-file=no -e 'println(STDERR,getpid())'`, stderr = out))
+    pid = getpid(proc)
+    close(out.in)
+    @test parse(Int32, read(out, String)) == pid
+    @test success(proc)
+    @test getpid(proc) == -1
+end
+
 # issue #6310
 @test read(pipeline(`$echocmd "2+2"`, `$exename --startup-file=no`), String) == "4\n"