From 42e976aaed4b4a01fc55cb56e789144849807aac Mon Sep 17 00:00:00 2001
From: Jesse Luehrs <doy@tozt.net>
Date: Sat, 12 Feb 2022 13:00:51 -0500
Subject: simplify

---
 src/prelude.rs    | 37 +++++++++++++++++++++++++++++++++++++
 src/runner/sys.rs | 26 ++++++++------------------
 2 files changed, 45 insertions(+), 18 deletions(-)

(limited to 'src')

diff --git a/src/prelude.rs b/src/prelude.rs
index 6789a1f..c647591 100644
--- a/src/prelude.rs
+++ b/src/prelude.rs
@@ -9,3 +9,40 @@ pub use std::os::unix::ffi::{OsStrExt as _, OsStringExt as _};
 pub use std::os::unix::io::{AsRawFd as _, FromRawFd as _, IntoRawFd as _};
 pub use std::os::unix::process::ExitStatusExt as _;
 pub use users::os::unix::UserExt as _;
+
+pub use ext::Result as _;
+
+mod ext {
+    pub trait Result {
+        type T;
+        type E;
+
+        fn allow(self, allow_e: Self::E) -> Self;
+        fn allow_with(self, allow_e: Self::E, default_t: Self::T) -> Self;
+    }
+
+    impl<T, E> Result for std::result::Result<T, E>
+    where
+        T: std::default::Default,
+        E: std::cmp::PartialEq,
+    {
+        type T = T;
+        type E = E;
+
+        fn allow(self, allow_e: Self::E) -> Self {
+            self.or_else(|e| {
+                if e == allow_e {
+                    Ok(std::default::Default::default())
+                } else {
+                    Err(e)
+                }
+            })
+        }
+
+        fn allow_with(self, allow_e: Self::E, default_t: Self::T) -> Self {
+            self.or_else(
+                |e| if e == allow_e { Ok(default_t) } else { Err(e) },
+            )
+        }
+    }
+}
diff --git a/src/runner/sys.rs b/src/runner/sys.rs
index 9cb1c2e..413882c 100644
--- a/src/runner/sys.rs
+++ b/src/runner/sys.rs
@@ -46,14 +46,8 @@ pub fn set_foreground_pg(pg: nix::unistd::Pid) -> anyhow::Result<()> {
     nix::unistd::close(pty)?;
 
     nix::sys::signal::kill(neg_pid(pg), nix::sys::signal::Signal::SIGCONT)
-        .or_else(|e| {
-            // the process group has already exited
-            if e == nix::errno::Errno::ESRCH {
-                Ok(())
-            } else {
-                Err(e)
-            }
-        })?;
+        // the process group has already exited
+        .allow(nix::errno::Errno::ESRCH)?;
 
     Ok(())
 }
@@ -67,16 +61,12 @@ pub fn setpgid_parent(
     pid: nix::unistd::Pid,
     pg: Option<nix::unistd::Pid>,
 ) -> anyhow::Result<()> {
-    nix::unistd::setpgid(pid, pg.unwrap_or(PID0)).or_else(|e| {
-        // EACCES means that the child already called exec, but if it did,
-        // then it also must have already called setpgid itself, so we don't
-        // care. ESRCH means that the process already exited, which is similar
-        if e == nix::errno::Errno::EACCES || e == nix::errno::Errno::ESRCH {
-            Ok(())
-        } else {
-            Err(e)
-        }
-    })?;
+    nix::unistd::setpgid(pid, pg.unwrap_or(PID0))
+        // the child already called exec, so it must have already called
+        // setpgid itself
+        .allow(nix::errno::Errno::EACCES)
+        // the child already exited, so we don't care
+        .allow(nix::errno::Errno::ESRCH)?;
     Ok(())
 }
 
-- 
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