From eabe3481820358b2d4c20f5e2542d48a2449af83 Mon Sep 17 00:00:00 2001
From: belovdv <70999565+belovdv@users.noreply.github.com>
Date: Thu, 1 Feb 2024 21:47:10 +0300
Subject: [PATCH] disable jobserver on unix, if file descriptors are negative

---
 src/error.rs |  2 +-
 src/unix.rs  | 10 ++++++++--
 2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/src/error.rs b/src/error.rs
index 8b3fe74..6b20f29 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -15,7 +15,7 @@ pub struct FromEnvError {
 pub enum FromEnvErrorKind {
     /// There is no environment variable that describes jobserver to inherit.
     NoEnvVar,
-    /// There is no jobserver in the environment variable.
+    /// There is no jobserver in the environment variable, or it was disabled.
     /// Variables associated with Make can be used for passing data other than jobserver info.
     NoJobserver,
     /// Cannot parse jobserver environment variable value, incorrect format.
diff --git a/src/unix.rs b/src/unix.rs
index ee1e923..0a8e21d 100644
--- a/src/unix.rs
+++ b/src/unix.rs
@@ -123,13 +123,19 @@ impl Client {
             Some(w) => w,
             None => return Ok(None),
         };
-        let read = read
+        let read: c_int = read
             .parse()
             .map_err(|e| FromEnvErrorInner::CannotParse(format!("cannot parse `read` fd: {e}")))?;
-        let write = write
+        let write: c_int = write
             .parse()
             .map_err(|e| FromEnvErrorInner::CannotParse(format!("cannot parse `write` fd: {e}")))?;
 
+        // If either or both of these file descriptors are negative,
+        // it means the jobserver is disabled for this process.
+        if read < 0 || write < 0 {
+            return Err(FromEnvErrorInner::NoJobserver);
+        }
+
         // Ok so we've got two integers that look like file descriptors, but
         // for extra sanity checking let's see if they actually look like
         // valid files and instances of a pipe if feature enabled before we