Improve error handling

2 files changed, 51 insertions, 6 deletions

diff --git a/src/wait/error.rs b/src/wait/error.rs
index bb95e81..169097d 100644
--- a/src/wait/error.rs
+++ b/src/wait/error.rs
@@ -2,11 +2,22 @@ use nix;
 use std::time::Duration;
 
 #[derive(Debug)]
+pub struct ProcessSignalInfo {
+    pub pid: nix::unistd::Pid,
+    pub signal: nix::sys::signal::Signal,
+    pub coredump: bool
+}
+
+#[derive(Debug)]
 pub enum WaitError {
     TimedOut(Duration),
-    OsError(nix::Error)
+    ReturnNonZero(i32, nix::unistd::Pid),
+    Signaled(ProcessSignalInfo),
+    OsError(nix::Error),
+    NotExited
 }
 
+
 impl From<nix::Error> for WaitError {
     fn from(err: nix::Error) -> Self {
         WaitError::OsError(err)
@@ -17,7 +28,13 @@ impl std::fmt::Display for WaitError {
     fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
         match *self {
             WaitError::TimedOut(dur) => write!(f, "process timed out in {:?}", dur),
-            WaitError::OsError(err) => err.fmt(f)
+            WaitError::ReturnNonZero(ret, pid) =>
+                write!(f, "process exited with non-zero exit code ({}). was {}", ret, pid),
+            WaitError::Signaled(ref info) =>
+                write!(f, "process killed by {} {}. was {}",
+                       info.signal, if info.coredump {"(core dumped)"} else {""}, info.pid),
+            WaitError::OsError(err) => err.fmt(f),
+            WaitError::NotExited => write!(f, "process signaled, but not exited")
         }
     }
 }
@@ -25,7 +42,10 @@ impl std::fmt::Display for WaitError {
 impl std::error::Error for WaitError {
     fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
         match *self {
-            WaitError::TimedOut(_) => None,
+            WaitError::TimedOut(_) |
+            WaitError::ReturnNonZero(_, _) |
+            WaitError::Signaled(_) |
+            WaitError::NotExited => None,
             WaitError::OsError(ref e) => Some(e)
         }
     }
diff --git a/src/wait/mod.rs b/src/wait/mod.rs
index 9761f08..c591bb1 100644
--- a/src/wait/mod.rs
+++ b/src/wait/mod.rs
@@ -8,20 +8,45 @@ use std::time::{ Instant, Duration };
 use std::process::Child;
 use std::thread;
 use std::sync::mpsc;
+use std::convert::{ TryFrom, TryInto };
 
 mod error;
 mod rusage_ffi;
 pub use rusage_ffi::Rusage;
 
 pub use error::WaitError;
+use error::ProcessSignalInfo;
 
 #[derive(Debug)]
-pub struct WaitInfo {
+struct WaitInfo {
     pub status: WaitStatus,
     pub usage: Rusage,
     pub wall_time: Duration
 }
 
+#[derive(Debug)]
+pub struct ChildExitStatus {
+    pub usage: Rusage,
+    pub wall_time: Duration
+}
+
+impl TryFrom<WaitInfo> for ChildExitStatus {
+    type Error = WaitError;
+
+    fn try_from(info: WaitInfo) -> Result<Self, Self::Error> {
+        match info.status {
+            WaitStatus::Exited(pid, ret) =>
+                match ret {
+                    0 => Ok(ChildExitStatus { usage: info.usage, wall_time: info.wall_time }),
+                    _ => Err(WaitError::ReturnNonZero(ret, pid))
+                },
+            WaitStatus::Signaled(pid, signal, coredump) =>
+                Err(WaitError::Signaled(ProcessSignalInfo { pid, signal, coredump })),
+            _ => Err(WaitError::NotExited)
+        }
+    }
+}
+
 
 fn wait4_pid(
     pid: Pid,
@@ -57,14 +82,14 @@ pub fn wait_child(
     mut child: Child,
     timeout: Duration,
     timer: Instant
-) -> Result<WaitInfo, WaitError> {
+) -> Result<ChildExitStatus, WaitError> {
     let pid = Pid::from_raw(child.id() as i32);
     let (send, recv) = mpsc::channel();
 
     let thr = thread::spawn(move || wait4_pid(pid, send, timer));
 
     match recv.recv_timeout(timeout) {
-        Ok(Ok(usg)) => Ok(usg),
+        Ok(Ok(wait_info)) => wait_info.try_into(),
         Ok(Err(err)) => Err(err.into()),
         Err(mpsc::RecvTimeoutError::Timeout) => {
             drop(recv);