1 files changed, 89 insertions, 1 deletions

diff --git a/ext/js/background/request-builder.js b/ext/js/background/request-builder.js
index ad1536f1..2cdd6f0e 100644
--- a/ext/js/background/request-builder.js
+++ b/ext/js/background/request-builder.js
@@ -42,6 +42,58 @@ class RequestBuilder {
         return await this._fetchInternal(url, init, headerModifications);
     }
 
+    static async readFetchResponseArrayBuffer(response, onProgress) {
+        let reader;
+        try {
+            if (typeof onProgress === 'function') {
+                reader = response.body.getReader();
+            }
+        } catch (e) {
+            // Not supported
+        }
+
+        if (typeof reader === 'undefined') {
+            const result = await response.arrayBuffer();
+            if (typeof onProgress === 'function') {
+                onProgress(true);
+            }
+            return result;
+        }
+
+        const contentLengthString = response.headers.get('Content-Length');
+        const contentLength = contentLengthString !== null ? Number.parseInt(contentLengthString, 10) : null;
+        let target = Number.isFinite(contentLength) ? new Uint8Array(contentLength) : null;
+        let targetPosition = 0;
+        let totalLength = 0;
+        const targets = [];
+
+        while (true) {
+            const {done, value} = await reader.read();
+            if (done) { break; }
+            onProgress(false);
+            if (target === null) {
+                targets.push({array: value, length: value.length});
+            } else if (targetPosition + value.length > target.length) {
+                targets.push({array: target, length: targetPosition});
+                target = null;
+            } else {
+                target.set(value, targetPosition);
+                targetPosition += value.length;
+            }
+            totalLength += value.length;
+        }
+
+        if (target === null) {
+            target = this._joinUint8Arrays(targets, totalLength);
+        } else if (totalLength < target.length) {
+            target = target.slice(0, totalLength);
+        }
+
+        onProgress(true);
+
+        return target;
+    }
+
     // Private
 
     async _fetchInternal(url, init, headerModifications) {
@@ -92,7 +144,10 @@ class RequestBuilder {
                 }, 100);
             }
             const details = await errorDetailsPromise;
-            e.data = {details};
+            if (details !== null) {
+                const data = {details};
+                this._assignErrorData(e, data);
+            }
             throw e;
         } finally {
             this._removeWebRequestEventListeners(eventListeners);
@@ -295,4 +350,37 @@ class RequestBuilder {
         }
         return result;
     }
+
+    _assignErrorData(error, data) {
+        try {
+            error.data = data;
+        } catch (e) {
+            // On Firefox, assigning DOMException.data can fail in certain contexts.
+            // https://bugzilla.mozilla.org/show_bug.cgi?id=1776555
+            try {
+                Object.defineProperty(error, 'data', {
+                    configurable: true,
+                    enumerable: true,
+                    writable: true,
+                    value: data
+                });
+            } catch (e2) {
+                // NOP
+            }
+        }
+    }
+
+    static _joinUint8Arrays(items, totalLength) {
+        if (items.length === 1) {
+            const {array, length} = items[0];
+            if (array.length === length) { return array; }
+        }
+        const result = new Uint8Array(totalLength);
+        let position = 0;
+        for (const {array, length} of items) {
+            result.set(array, position);
+            position += length;
+        }
+        return result;
+    }
 }