Merge pull request #832 from microsoft/tyriar/partial_eagain

Ensure partial writes are handled on EAGAIN

Author: Tyriar

src/unixTerminal.ts

@@ -189,6 +189,11 @@ export class UnixTerminal extends Terminal {
     // than using the `net.Socket`/`tty.WriteStream` wrappers which swallow the
     // errors and cause the thread to block indefinitely.
     fs.write(this._fd, data, (err, written) => {
+      // Requeue any partial writes
+      if (written < data.length) {
+        this._writeQueue.unshift(data.slice(written));
+      }
+
       if (err) {
         const errno = (err as any).errno;
         switch (errno) {
@@ -216,11 +221,6 @@ export class UnixTerminal extends Terminal {
         }
       }
 
-      // Requeue any partial writes
-      if (written < data.length) {
-        this._writeQueue.unshift(data.slice(written));
-      }
-
       // Using `setImmediate` here appears to corrupt the data, this may be what
       // the interleaving/dropped data comment is about in Node.js' tty module:
       // https://github.com/nodejs/node/blob/4cac2b94bed4bf02810be054e8f63c0048c66564/lib/tty.js#L106C1-L111C34