Pass an error to the sys.pump callback if one occurs

- Add test case for pumping from unreadable stream.
- Document the sys.pump error handling behavior

doc/api.markdown

@@ -860,8 +860,9 @@ Experimental
 
 Read the data from `readableStream` and send it to the `writableStream`.
 When `writeableStream.write(data)` returns `false` `readableStream` will be
-paused until the `drain` event occurs on the `writableStream`. `callback` is
-called when `writableStream` is closed.
+paused until the `drain` event occurs on the `writableStream`. `callback` gets
+an error as its only argument and is called when `writableStream` is closed or
+when an error occurs.
 
 
 ## Timers

lib/sys.js

@@ -309,6 +309,11 @@ exports.pump = function (readStream, writeStream, callback) {
   readStream.addListener("close", function () {
     if (callback) callback();
   });
+
+  readStream.addListener("error", function(err) {
+    writeStream.end();
+    if (callback) callback(err);
+  });
 };
 
 /**

test/simple/test-pump-file2tcp-noexist.js

@@ -0,0 +1,52 @@
+common = require("../common");
+assert = common.assert
+net = require("net");
+fs = require("fs");
+sys = require("sys");
+path = require("path");
+fn = path.join(common.fixturesDir, 'does_not_exist.txt');
+
+var got_error = false;
+var conn_closed = false;
+
+server = net.createServer(function (stream) {
+  common.error('pump!');
+  sys.pump(fs.createReadStream(fn), stream, function (err) {
+    common.error("sys.pump's callback fired");
+    if (err) {
+      got_error = true;
+    } else {
+      common.debug("sys.pump's callback fired with no error");
+      common.debug("this shouldn't happen as the file doesn't exist...");
+      assert.equal(true, false);
+    }
+    server.close();
+  });
+});
+
+server.listen(common.PORT, function () {
+  conn = net.createConnection(common.PORT);
+  conn.setEncoding('utf8');
+  conn.addListener("data", function (chunk) {
+    common.error('recv data! nchars = ' + chunk.length);
+    buffer += chunk;
+  });
+
+  conn.addListener("end", function () {
+    conn.end();
+  });
+
+  conn.addListener("close", function () {
+    common.error('client connection close');
+    conn_closed = true;
+  });
+});
+
+var buffer = '';
+count = 0;
+
+process.addListener('exit', function () {
+  assert.equal(true, got_error);
+  assert.equal(true, conn_closed);
+  console.log("exiting");
+});