From 831ff775703eb5126f741fc3be1cf829ec060011 Mon Sep 17 00:00:00 2001
From: Corentin Henry <corentinhenry@gmail.com>
Date: Thu, 25 Jan 2018 15:08:48 -0800
Subject: [PATCH 1/3] implement Send for process::Command on unix

closes https://github.com/rust-lang/rust/issues/47751
---
 src/libstd/sys/unix/process/process_common.rs | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/src/libstd/sys/unix/process/process_common.rs b/src/libstd/sys/unix/process/process_common.rs
index c53bcdbf8e36f..b09fc36dee0be 100644
--- a/src/libstd/sys/unix/process/process_common.rs
+++ b/src/libstd/sys/unix/process/process_common.rs
@@ -87,6 +87,11 @@ pub enum Stdio {
     Fd(FileDesc),
 }
 
+// Command is not Send by default due to the Command.argv field containing a raw pointers. However
+// it is safe to implement Send, because anyway, these pointers point to memory owned by the
+// Command.args field.
+unsafe impl Send for Command {}
+
 impl Command {
     pub fn new(program: &OsStr) -> Command {
         let mut saw_nul = false;

From 9e6ed17c4f5befef64fa9e8a1d2b2f155c345cac Mon Sep 17 00:00:00 2001
From: Corentin Henry <corentinhenry@gmail.com>
Date: Fri, 26 Jan 2018 07:22:43 -0800
Subject: [PATCH 2/3] make Command.argv Send on unix platforms

Implementing Send for a specific field rather than the whole struct is
safer: if a field is changed/modified and becomes non-Send, we can catch
it.
---
 src/libstd/sys/unix/process/process_common.rs | 21 ++++++++++---------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/src/libstd/sys/unix/process/process_common.rs b/src/libstd/sys/unix/process/process_common.rs
index b09fc36dee0be..7e057401fab70 100644
--- a/src/libstd/sys/unix/process/process_common.rs
+++ b/src/libstd/sys/unix/process/process_common.rs
@@ -45,7 +45,7 @@ pub struct Command {
     // other keys.
     program: CString,
     args: Vec<CString>,
-    argv: Vec<*const c_char>,
+    argv: Argv,
     env: CommandEnv<DefaultEnvKey>,
 
     cwd: Option<CString>,
@@ -58,6 +58,12 @@ pub struct Command {
     stderr: Option<Stdio>,
 }
 
+// Create a new type for argv, so that we can make it `Send`
+struct Argv(Vec<*const c_char>);
+
+// It is safe to make Argv Send, because it contains pointers to memory owned by `Command.args`
+unsafe impl Send for Argv {}
+
 // passed back to std::process with the pipes connected to the child, if any
 // were requested
 pub struct StdioPipes {
@@ -87,17 +93,12 @@ pub enum Stdio {
     Fd(FileDesc),
 }
 
-// Command is not Send by default due to the Command.argv field containing a raw pointers. However
-// it is safe to implement Send, because anyway, these pointers point to memory owned by the
-// Command.args field.
-unsafe impl Send for Command {}
-
 impl Command {
     pub fn new(program: &OsStr) -> Command {
         let mut saw_nul = false;
         let program = os2c(program, &mut saw_nul);
         Command {
-            argv: vec![program.as_ptr(), ptr::null()],
+            argv: Argv(vec![program.as_ptr(), ptr::null()]),
             program,
             args: Vec::new(),
             env: Default::default(),
@@ -116,8 +117,8 @@ impl Command {
         // Overwrite the trailing NULL pointer in `argv` and then add a new null
         // pointer.
         let arg = os2c(arg, &mut self.saw_nul);
-        self.argv[self.args.len() + 1] = arg.as_ptr();
-        self.argv.push(ptr::null());
+        self.argv.0[self.args.len() + 1] = arg.as_ptr();
+        self.argv.0.push(ptr::null());
 
         // Also make sure we keep track of the owned value to schedule a
         // destructor for this memory.
@@ -138,7 +139,7 @@ impl Command {
         self.saw_nul
     }
     pub fn get_argv(&self) -> &Vec<*const c_char> {
-        &self.argv
+        &self.argv.0
     }
 
     #[allow(dead_code)]

From 077d3434aa8a2a3064afcc1c9406a49d0acf0a8d Mon Sep 17 00:00:00 2001
From: Corentin Henry <corentinhenry@gmail.com>
Date: Fri, 26 Jan 2018 07:33:58 -0800
Subject: [PATCH 3/3] add test checking that process::Command is Send

---
 src/libstd/process.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/libstd/process.rs b/src/libstd/process.rs
index 5c66ac6ddded8..9b2f815b71383 100644
--- a/src/libstd/process.rs
+++ b/src/libstd/process.rs
@@ -1843,4 +1843,10 @@ mod tests {
         }
         assert!(events > 0);
     }
+
+    #[test]
+    fn test_command_implements_send() {
+        fn take_send_type<T: Send>(_: T) {}
+        take_send_type(Command::new(""))
+    }
 }