Move as much I/O as possible off of native::io

When uv's TTY I/O is used for the stdio streams, the file descriptors are put
into a non-blocking mode. This means that other concurrent writes to the same
stream can fail with EAGAIN or EWOULDBLOCK. By all I/O to event-loop I/O, we
avoid this error.

There is one location which cannot move, which is the runtime's dumb_println
function. This was implemented to handle the EAGAIN and EWOULDBLOCK errors and
simply retry again and again.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/libstd/rt/io/native/file.rs b/src/libstd/rt/io/native/file.rs
index d6820981181..a2b2289679a 100644
--- a/src/libstd/rt/io/native/file.rs
+++ b/src/libstd/rt/io/native/file.rs
@@ -21,6 +21,12 @@ fn raise_error() {
     // XXX: this should probably be a bit more descriptive...
     let (kind, desc) = match os::errno() as i32 {
         libc::EOF => (EndOfFile, "end of file"),
+
+        // These two constants can have the same value on some systems, but
+        // different values on others, so we can't use a match clause
+        x if x == libc::EAGAIN || x == libc::EWOULDBLOCK =>
+            (ResourceUnavailable, "resource temporarily unavailable"),
+
         _ => (OtherIoError, "unknown error"),
     };