switch to nix for killing preview subprocess

src/fail.rs

@@ -105,7 +105,9 @@ pub enum HError {
     #[fail(display = "FileBrowser needs to know about all tab's files to run exec!")]
     FileBrowserNeedTabFiles,
     #[fail(display = "{}", _0)]
-    FileError(crate::files::FileError)
+    FileError(crate::files::FileError),
+    #[fail(display = "{}", _0)]
+    Nix(#[cause] nix::Error)
 }
 
 impl HError {
@@ -367,6 +369,13 @@ impl From<std::num::ParseIntError> for HError {
     }
 }
 
+impl From<nix::Error> for HError {
+    fn from(error: nix::Error) -> Self {
+        let err = HError::Nix(error);
+        err
+    }
+}
+
 impl From<std::char::ParseCharError> for HError {
     fn from(error: std::char::ParseCharError) -> Self {
         let err = HError::ParseCharError(error);

src/preview.rs

@@ -27,16 +27,16 @@ fn kill_proc() -> HResult<()> {
     pid.map(|pid|
             // Do this in another thread so we can wait on process to exit with SIGHUP
             std::thread::spawn(move || {
+                use nix::{unistd::Pid,
+                          sys::signal::{killpg, Signal}};
+
                 let sleep_time = std::time::Duration::from_millis(50);
 
-                // Here be dragons
-                unsafe {
-                    // Kill using process group, to clean up all child processes, too
-                    // 15 = SIGTERM, 9 = SIGKILL
-                    libc::killpg(pid as i32, 15);
-                    std::thread::sleep(sleep_time);
-                    libc::killpg(pid as i32, 9);
-                }
+                // Kill using process group, to clean up all child processes, too
+                let pid = Pid::from_raw(pid as i32);
+                killpg(pid, Signal::SIGTERM).log();
+                std::thread::sleep(sleep_time);
+                killpg(pid, Signal::SIGKILL).log();
             })
     );
     *pid = None;