Move pthread::Errno to separate module.

src/error.rs

@@ -0,0 +1,34 @@
+use crate::platform::types::c_int;
+
+/// Positive error codes (EINVAL, not -EINVAL).
+#[derive(Debug, Eq, PartialEq)]
+// TODO: Move to a more generic place.
+pub struct Errno(pub c_int);
+
+#[cfg(target_os = "redox")]
+impl From<syscall::Error> for Errno {
+    fn from(value: syscall::Error) -> Self {
+        Errno(value.errno)
+    }
+}
+#[cfg(target_os = "redox")]
+impl From<Errno> for syscall::Error {
+    fn from(value: Errno) -> Self {
+        syscall::Error::new(value.0)
+    }
+}
+
+pub trait ResultExt<T> {
+    fn or_minus_one_errno(self) -> T;
+}
+impl<T: From<i8>> ResultExt<T> for Result<T, Errno> {
+    fn or_minus_one_errno(self) -> T {
+        match self {
+            Self::Ok(v) => v,
+            Self::Err(Errno(errno)) => unsafe {
+                crate::platform::ERRNO.set(errno);
+                T::from(-1)
+            },
+        }
+    }
+}