1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
|
/* 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/. */
import { Domain } from "chrome://remote/content/cdp/domains/Domain.sys.mjs";
import { StreamRegistry } from "chrome://remote/content/cdp/StreamRegistry.sys.mjs";
const DEFAULT_CHUNK_SIZE = 10 * 1024 * 1024;
// Global singleton for managing open streams
export const streamRegistry = new StreamRegistry();
export class IO extends Domain {
// commands
/**
* Close the stream, discard any temporary backing storage.
*
* @param {object} options
* @param {string} options.handle
* Handle of the stream to close.
*/
async close(options = {}) {
const { handle } = options;
if (typeof handle != "string") {
throw new TypeError(`handle: string value expected`);
}
await streamRegistry.remove(handle);
}
/**
* Read a chunk of the stream.
*
* @param {object} options
* @param {string} options.handle
* Handle of the stream to read.
* @param {number=} options.offset
* Seek to the specified offset before reading. If not specificed,
* proceed with offset following the last read.
* Some types of streams may only support sequential reads.
* @param {number=} options.size
* Maximum number of bytes to read (left upon the agent
* discretion if not specified).
*
* @returns {object}
* Data that were read, including flags for base64-encoded, and end-of-file reached.
*/
async read(options = {}) {
const { handle, offset, size } = options;
if (typeof handle != "string") {
throw new TypeError(`handle: string value expected`);
}
const stream = streamRegistry.get(handle);
if (typeof offset != "undefined") {
if (typeof offset != "number") {
throw new TypeError(`offset: integer value expected`);
}
await stream.seek(offset);
}
const remainingBytes = await stream.available();
let chunkSize;
if (typeof size != "undefined") {
if (typeof size != "number") {
throw new TypeError(`size: integer value expected`);
}
// Chromium currently crashes for negative sizes (https://bit.ly/2P6h0Fv),
// but might behave similar to the offset and clip invalid values
chunkSize = Math.max(0, Math.min(size, remainingBytes));
} else {
chunkSize = Math.min(DEFAULT_CHUNK_SIZE, remainingBytes);
}
const bytes = await stream.readBytes(chunkSize);
// Each UCS2 character has an upper byte of 0 and a lower byte matching
// the binary data. Using a loop here prevents us from hitting the browser's
// internal `arguments.length` limit.
const ARGS_MAX = 262144;
const stringData = [];
for (let i = 0; i < bytes.length; i += ARGS_MAX) {
let argsChunk = Math.min(bytes.length, i + ARGS_MAX);
stringData.push(
String.fromCharCode.apply(null, bytes.slice(i, argsChunk))
);
}
const data = btoa(stringData.join(""));
return {
data,
base64Encoded: true,
eof: remainingBytes - bytes.length == 0,
};
}
}
|
