1 files changed, 104 insertions, 0 deletions
diff --git a/toolkit/jetpack/sdk/io/byte-streams.js b/toolkit/jetpack/sdk/io/byte-streams.js
new file mode 100644
index 000000000..6afab4369
--- /dev/null
+++ b/toolkit/jetpack/sdk/io/byte-streams.js
@@ -0,0 +1,104 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+module.metadata = {
+  "stability": "experimental"
+};
+
+exports.ByteReader = ByteReader;
+exports.ByteWriter = ByteWriter;
+
+const {Cc, Ci} = require("chrome");
+
+// This just controls the maximum number of bytes we read in at one time.
+const BUFFER_BYTE_LEN = 0x8000;
+
+function ByteReader(inputStream) {
+  const self = this;
+
+  let stream = Cc["@mozilla.org/binaryinputstream;1"].
+               createInstance(Ci.nsIBinaryInputStream);
+  stream.setInputStream(inputStream);
+
+  let manager = new StreamManager(this, stream);
+
+  this.read = function ByteReader_read(numBytes) {
+    manager.ensureOpened();
+    if (typeof(numBytes) !== "number")
+      numBytes = Infinity;
+
+    let data = "";
+    let read = 0;
+    try {
+      while (true) {
+        let avail = stream.available();
+        let toRead = Math.min(numBytes - read, avail, BUFFER_BYTE_LEN);
+        if (toRead <= 0)
+          break;
+        data += stream.readBytes(toRead);
+        read += toRead;
+      }
+    }
+    catch (err) {
+      throw new Error("Error reading from stream: " + err);
+    }
+
+    return data;
+  };
+}
+
+function ByteWriter(outputStream) {
+  const self = this;
+
+  let stream = Cc["@mozilla.org/binaryoutputstream;1"].
+               createInstance(Ci.nsIBinaryOutputStream);
+  stream.setOutputStream(outputStream);
+
+  let manager = new StreamManager(this, stream);
+
+  this.write = function ByteWriter_write(str) {
+    manager.ensureOpened();
+    try {
+      stream.writeBytes(str, str.length);
+    }
+    catch (err) {
+      throw new Error("Error writing to stream: " + err);
+    }
+  };
+}
+
+
+// This manages the lifetime of stream, a ByteReader or ByteWriter.  It defines
+// closed and close() on stream and registers an unload listener that closes
+// rawStream if it's still opened.  It also provides ensureOpened(), which
+// throws an exception if the stream is closed.
+function StreamManager(stream, rawStream) {
+  const self = this;
+  this.rawStream = rawStream;
+  this.opened = true;
+
+  stream.__defineGetter__("closed", function stream_closed() {
+    return !self.opened;
+  });
+
+  stream.close = function stream_close() {
+    self.ensureOpened();
+    self.unload();
+  };
+
+  require("../system/unload").ensure(this);
+}
+
+StreamManager.prototype = {
+  ensureOpened: function StreamManager_ensureOpened() {
+    if (!this.opened)
+      throw new Error("The stream is closed and cannot be used.");
+  },
+  unload: function StreamManager_unload() {
+    this.rawStream.close();
+    this.opened = false;
+  }
+};