1 files changed, 139 insertions, 0 deletions
diff --git a/remote/cdp/StreamRegistry.sys.mjs b/remote/cdp/StreamRegistry.sys.mjs
new file mode 100644
index 0000000000..9474f16a57
--- /dev/null
+++ b/remote/cdp/StreamRegistry.sys.mjs
@@ -0,0 +1,139 @@
+/* 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/. */
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  generateUUID: "chrome://remote/content/shared/UUID.sys.mjs",
+  UnsupportedError: "chrome://remote/content/cdp/Error.sys.mjs",
+});
+
+export class Stream {
+  #path;
+  #offset;
+  #length;
+
+  constructor(path) {
+    this.#path = path;
+    this.#offset = 0;
+    this.#length = null;
+  }
+
+  async destroy() {
+    await IOUtils.remove(this.#path);
+  }
+
+  async seek(seekTo) {
+    // To keep compatibility with Chrome clip invalid offsets
+    this.#offset = Math.max(0, Math.min(seekTo, await this.length()));
+  }
+
+  async readBytes(count) {
+    const bytes = await IOUtils.read(this.#path, {
+      offset: this.#offset,
+      maxBytes: count,
+    });
+    this.#offset += bytes.length;
+    return bytes;
+  }
+
+  async available() {
+    const length = await this.length();
+    return length - this.#offset;
+  }
+
+  async length() {
+    if (this.#length === null) {
+      const info = await IOUtils.stat(this.#path);
+      this.#length = info.size;
+    }
+
+    return this.#length;
+  }
+
+  get path() {
+    return this.#path;
+  }
+}
+
+export class StreamRegistry {
+  constructor() {
+    // handle => stream
+    this.streams = new Map();
+
+    // Register an async shutdown blocker to ensure all open IO streams are
+    // closed, and remaining temporary files removed. Needs to happen before
+    // IOUtils has been shutdown.
+    IOUtils.profileBeforeChange.addBlocker(
+      "Remote Agent: Clean-up of open streams",
+      async () => {
+        await this.destructor();
+      }
+    );
+  }
+
+  async destructor() {
+    for (const stream of this.streams.values()) {
+      await stream.destroy();
+    }
+
+    this.streams.clear();
+  }
+
+  /**
+   * Add a new stream to the registry.
+   *
+   * @param {Stream} stream
+   *      The stream to use.
+   *
+   * @returns {string}
+   *     Stream handle (uuid)
+   */
+  add(stream) {
+    if (!(stream instanceof Stream)) {
+      // Bug 1602731 - Implement support for blob
+      throw new lazy.UnsupportedError(`Unknown stream type for ${stream}`);
+    }
+
+    const handle = lazy.generateUUID();
+
+    this.streams.set(handle, stream);
+    return handle;
+  }
+
+  /**
+   * Get a stream from the registry.
+   *
+   * @param {string} handle
+   *      Handle of the stream to retrieve.
+   *
+   * @returns {Stream}
+   *      The requested stream.
+   */
+  get(handle) {
+    const stream = this.streams.get(handle);
+
+    if (!stream) {
+      throw new TypeError(`Invalid stream handle`);
+    }
+
+    return stream;
+  }
+
+  /**
+   * Remove a stream from the registry.
+   *
+   * @param {string} handle
+   *      Handle of the stream to remove.
+   *
+   * @returns {boolean}
+   *     true if successfully removed
+   */
+  async remove(handle) {
+    const stream = this.get(handle);
+    await stream.destroy();
+
+    return this.streams.delete(handle);
+  }
+}