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
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
|
'use strict';
const common = require('../common');
const assert = require('assert');
if (!common.hasCrypto) {
common.skip('missing crypto');
return;
}
const crypto = require('crypto');
const stream = require('stream');
const Stream = stream.Stream;
const util = require('util');
const zlib = require('zlib');
// emit random bytes, and keep a shasum
function RandomReadStream(opt) {
Stream.call(this);
this.readable = true;
this._paused = false;
this._processing = false;
this._hasher = crypto.createHash('sha1');
opt = opt || {};
// base block size.
opt.block = opt.block || 256 * 1024;
// total number of bytes to emit
opt.total = opt.total || 256 * 1024 * 1024;
this._remaining = opt.total;
// how variable to make the block sizes
opt.jitter = opt.jitter || 1024;
this._opt = opt;
this._process = this._process.bind(this);
process.nextTick(this._process);
}
util.inherits(RandomReadStream, Stream);
RandomReadStream.prototype.pause = function() {
this._paused = true;
this.emit('pause');
};
RandomReadStream.prototype.resume = function() {
// console.error("rrs resume");
this._paused = false;
this.emit('resume');
this._process();
};
RandomReadStream.prototype._process = function() {
if (this._processing) return;
if (this._paused) return;
this._processing = true;
if (!this._remaining) {
this._hash = this._hasher.digest('hex').toLowerCase().trim();
this._processing = false;
this.emit('end');
return;
}
// figure out how many bytes to output
// if finished, then just emit end.
let block = this._opt.block;
const jitter = this._opt.jitter;
if (jitter) {
block += Math.ceil(Math.random() * jitter - (jitter / 2));
}
block = Math.min(block, this._remaining);
const buf = Buffer.allocUnsafe(block);
for (let i = 0; i < block; i++) {
buf[i] = Math.random() * 256;
}
this._hasher.update(buf);
this._remaining -= block;
console.error('block=%d\nremain=%d\n', block, this._remaining);
this._processing = false;
this.emit('data', buf);
process.nextTick(this._process);
};
// a filter that just verifies a shasum
function HashStream() {
Stream.call(this);
this.readable = this.writable = true;
this._hasher = crypto.createHash('sha1');
}
util.inherits(HashStream, Stream);
HashStream.prototype.write = function(c) {
// Simulate the way that an fs.ReadStream returns false
// on *every* write like a jerk, only to resume a
// moment later.
this._hasher.update(c);
process.nextTick(this.resume.bind(this));
return false;
};
HashStream.prototype.resume = function() {
this.emit('resume');
process.nextTick(this.emit.bind(this, 'drain'));
};
HashStream.prototype.end = function(c) {
if (c) {
this.write(c);
}
this._hash = this._hasher.digest('hex').toLowerCase().trim();
this.emit('data', this._hash);
this.emit('end');
};
const inp = new RandomReadStream({ total: 1024, block: 256, jitter: 16 });
const out = new HashStream();
const gzip = zlib.createGzip();
const gunz = zlib.createGunzip();
inp.pipe(gzip).pipe(gunz).pipe(out);
inp.on('data', function(c) {
console.error('inp data', c.length);
});
gzip.on('data', function(c) {
console.error('gzip data', c.length);
});
gunz.on('data', function(c) {
console.error('gunz data', c.length);
});
out.on('data', function(c) {
console.error('out data', c.length);
});
out.on('data', common.mustCall(function(c) {
console.error('hash=%s', c);
assert.strictEqual(c, inp._hash, 'hashes should match');
}));
|
