From ad1b4f3b2bc106760c950f961e98f913cf117e88 Mon Sep 17 00:00:00 2001
From: Michael Aaron Murphy <mmstickman@gmail.com>
Date: Sat, 14 Oct 2017 21:25:56 -0400
Subject: [PATCH] Optimize grouping for *nix archs

---
 Cargo.lock         |  1 +
 Cargo.toml         |  3 ++
 src/exec/ticket.rs | 73 ++++++++++++++++++++++++++++++++++++++++++++--
 src/main.rs        |  2 ++
 4 files changed, 76 insertions(+), 3 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index fc5935b..811623c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -8,6 +8,7 @@ dependencies = [
  "diff 0.1.10 (registry+https://github.com/rust-lang/crates.io-index)",
  "ignore 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 0.2.9 (registry+https://github.com/rust-lang/crates.io-index)",
+ "libc 0.2.31 (registry+https://github.com/rust-lang/crates.io-index)",
  "num_cpus 1.7.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex 0.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "regex-syntax 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)",
diff --git a/Cargo.toml b/Cargo.toml
index 156448f..44b46ec 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -40,6 +40,9 @@ num_cpus = "1.6.2"
 regex = "0.2"
 regex-syntax = "0.4"
 
+[target.'cfg(all(unix, not(target_os = "redox")))'.dependencies]
+libc = "0.2"
+
 [dev-dependencies]
 diff = "0.1"
 tempdir = "0.3"
diff --git a/src/exec/ticket.rs b/src/exec/ticket.rs
index 5a2ca9e..475daca 100644
--- a/src/exec/ticket.rs
+++ b/src/exec/ticket.rs
@@ -1,7 +1,7 @@
 use std::env;
-use std::process::{Command, Stdio};
+use std::process::Command;
 use std::sync::{Arc, Mutex};
-use std::io::{self, Write};
+use std::io;
 
 lazy_static! {
     /// On non-Windows systems, the `SHELL` environment variable will be used to determine the
@@ -29,8 +29,12 @@ impl<'a> CommandTicket<'a> {
     }
 
     /// Executes the command stored within the ticket, and
-    /// clearing the command's buffer when finished.
+    /// clearing the command's buffer when finished.'
+    #[cfg(not(all(unix, not(target_os = "redox"))))]
     pub fn then_execute(self) {
+        use std::process::Stdio;
+        use std::io::Write;
+
         // Spawn a shell with the supplied command.
         let cmd = Command::new(COMMAND.0.as_str())
             .arg(COMMAND.1)
@@ -58,4 +62,67 @@ impl<'a> CommandTicket<'a> {
         // Clear the buffer for later re-use.
         self.command.clear();
     }
+
+    #[cfg(all(unix, not(target_os = "redox")))]
+    pub fn then_execute(self) {
+        use libc::*;
+        use std::fs::File;
+        use std::os::unix::process::CommandExt;
+        use std::os::unix::io::FromRawFd;
+
+        // Initial a pair of pipes that will be used to
+        // pipe the std{out,err} of the spawned process.
+        let mut stdout_fds = [0; 2];
+        let mut stderr_fds = [0; 2];
+
+        unsafe {
+            pipe(stdout_fds.as_mut_ptr());
+            pipe(stderr_fds.as_mut_ptr());
+        }
+
+        // Spawn a shell with the supplied command.
+        let cmd = Command::new(COMMAND.0.as_str())
+            .arg(COMMAND.1)
+            .arg(&self.command)
+            .before_exec(move || unsafe {
+                // Configure the pipes accordingly in the child.
+                dup2(stdout_fds[1], STDOUT_FILENO);
+                dup2(stderr_fds[1], STDERR_FILENO);
+                close(stdout_fds[0]);
+                close(stdout_fds[1]);
+                close(stderr_fds[0]);
+                close(stderr_fds[1]);
+                Ok(())
+            })
+            .spawn();
+
+        // Open the read end of the pipes as `File`s.
+        let (mut pout, mut perr) = unsafe {
+            close(stdout_fds[1]);
+            close(stderr_fds[1]);
+            (
+                File::from_raw_fd(stdout_fds[0]),
+                File::from_raw_fd(stderr_fds[0]),
+            )
+        };
+
+        match cmd {
+            Ok(mut child) => {
+                let _ = child.wait();
+
+                // Create a lock to ensure that this thread has exclusive access to writing.
+                let _lock = self.out_perm.lock().unwrap();
+
+                // And then write the outputs of the process until EOF is sent to each file.
+                let stdout = io::stdout();
+                let stderr = io::stderr();
+                let _ = io::copy(&mut pout, &mut stdout.lock());
+                let _ = io::copy(&mut perr, &mut stderr.lock());
+            }
+            Err(why) => eprintln!("fd: exec error: {}", why),
+        }
+
+        // Clear the command string's buffer for later re-use.
+        self.command.clear();
+    }
 }
diff --git a/src/main.rs b/src/main.rs
index d52b856..d7574fd 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -5,6 +5,8 @@ extern crate clap;
 extern crate ignore;
 #[macro_use]
 extern crate lazy_static;
+#[cfg(all(unix, not(target_os = "redox")))]
+extern crate libc;
 extern crate num_cpus;
 extern crate regex;
 extern crate regex_syntax;