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buffer, doc: misc. fix and cleanup 

* Add official documentation that a Buffer instance is a viable
  argument when instantiating a new Buffer.
* Properly set the poolOffset when a buffer needs to be truncated.
* Add comments clarifying specific peculiar coding choices.
* Remove a level of unnecessary indentation.

Signed-off-by: Trevor Norris <trev.norris@gmail.com>
This commit is contained in:
Trevor Norris 2014-10-08 02:08:54 -07:00
parent bdc2ea4d52
commit 6462519d3c
2 changed files with 42 additions and 23 deletions
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6
doc/api/buffer.markdown
View File

@ -72,6 +72,12 @@ will be thrown here.
Allocates a new buffer using an `array` of octets. Allocates a new buffer using an `array` of octets.
### new Buffer(buffer)
* `buffer` {Buffer}
Copies the passed `buffer` data onto a new `Buffer` instance.
### new Buffer(str[, encoding]) ### new Buffer(str[, encoding])
* `str` String - string to encode. * `str` String - string to encode.

59
lib/buffer.js
View File

@ -49,17 +49,24 @@ function Buffer(subject, encoding) {
if (!util.isBuffer(this)) if (!util.isBuffer(this))
return new Buffer(subject, encoding); return new Buffer(subject, encoding);
if (util.isNumber(subject)) if (util.isNumber(subject)) {
this.length = subject > 0 ? subject >>> 0 : 0; this.length = subject > 0 ? subject >>> 0 : 0;
else if (util.isString(subject))
this.length = Buffer.byteLength(subject, encoding = encoding || 'utf8'); } else if (util.isString(subject)) {
else if (util.isObject(subject)) { if (!util.isString(encoding) || encoding.length === 0)
encoding = 'utf8';
this.length = Buffer.byteLength(subject, encoding);
// Handle Arrays, Buffers, Uint8Arrays or JSON.
} else if (util.isObject(subject)) {
if (subject.type === 'Buffer' && util.isArray(subject.data)) if (subject.type === 'Buffer' && util.isArray(subject.data))
subject = subject.data; subject = subject.data;
// Must use floor() because array length may be > kMaxLength.
this.length = +subject.length > 0 ? Math.floor(+subject.length) : 0; this.length = +subject.length > 0 ? Math.floor(+subject.length) : 0;
} else
} else {
throw new TypeError('must start with number, buffer, array or string'); throw new TypeError('must start with number, buffer, array or string');
}
if (this.length > kMaxLength) { if (this.length > kMaxLength) {
throw new RangeError('Attempt to allocate Buffer larger than maximum ' + throw new RangeError('Attempt to allocate Buffer larger than maximum ' +
@ -79,25 +86,31 @@ function Buffer(subject, encoding) {
alloc(this, this.length); alloc(this, this.length);
} }
if (!util.isNumber(subject)) { if (util.isNumber(subject)) {
if (util.isString(subject)) { return;
// In the case of base64 it's possible that the size of the buffer }
// allocated was slightly too large. In this case we need to rewrite
// the length to the actual length written.
var len = this.write(subject, encoding);
// Buffer was truncated after decode, realloc internal ExternalArray if (util.isString(subject)) {
if (len !== this.length) { // In the case of base64 it's possible that the size of the buffer
this.length = len; // allocated was slightly too large. In this case we need to rewrite
truncate(this, this.length); // the length to the actual length written.
} var len = this.write(subject, encoding);
} else { // Buffer was truncated after decode, realloc internal ExternalArray
if (util.isBuffer(subject)) if (len !== this.length) {
subject.copy(this, 0, 0, this.length); var prevLen = this.length;
else if (util.isNumber(subject.length) || util.isArray(subject)) this.length = len;
for (var i = 0; i < this.length; i++) truncate(this, this.length);
this[i] = subject[i]; poolOffset -= (prevLen - len);
} }
} else if (util.isBuffer(subject)) {
subject.copy(this, 0, 0, this.length);
} else if (util.isNumber(subject.length) || util.isArray(subject)) {
// Really crappy way to handle Uint8Arrays, but V8 doesn't give a simple
// way to access the data from the C++ API.
for (var i = 0; i < this.length; i++)
this[i] = subject[i];
} }
} }