mirror of https://github.com/perkeep/perkeep.git
72 lines
2.7 KiB
JavaScript
72 lines
2.7 KiB
JavaScript
/*
|
|
Copyright 2014 The Perkeep Authors
|
|
|
|
Licensed under the Apache License, Version 2.0 (the "License");
|
|
you may not use this file except in compliance with the License.
|
|
You may obtain a copy of the License at
|
|
|
|
http://www.apache.org/licenses/LICENSE-2.0
|
|
|
|
Unless required by applicable law or agreed to in writing, software
|
|
distributed under the License is distributed on an "AS IS" BASIS,
|
|
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
See the License for the specific language governing permissions and
|
|
limitations under the License.
|
|
*/
|
|
|
|
goog.provide('cam.blob');
|
|
|
|
goog.require('goog.crypt');
|
|
goog.require('goog.crypt.Sha1');
|
|
goog.require('goog.crypt.Sha224');
|
|
|
|
// Returns the Perkeep blobref for hash object. The hash function is currently sha224 or sha1, but more might be added later.
|
|
// @param {!goog.crypt.Hash} hash
|
|
// @returns {!string}
|
|
cam.blob.refFromHash = function(hash) {
|
|
if (hash instanceof goog.crypt.Sha224) {
|
|
return 'sha224-' + goog.crypt.byteArrayToHex(hash.digest());
|
|
}
|
|
if (hash instanceof goog.crypt.Sha1) {
|
|
return 'sha1-' + goog.crypt.byteArrayToHex(hash.digest());
|
|
}
|
|
throw new Error('Unsupported hash function type');
|
|
};
|
|
|
|
// Returns the Perkeep blobref for a string using the currently recommended hash function.
|
|
// @param {!string} str
|
|
// @returns {!string}
|
|
cam.blob.refFromString = function(str) {
|
|
var hash = cam.blob.createHash();
|
|
// update only supports 8 bit chars: http://docs.closure-library.googlecode.com/git/class_goog_crypt_Sha1.html
|
|
hash.update(goog.crypt.stringToUtf8ByteArray(str));
|
|
return cam.blob.refFromHash(hash);
|
|
};
|
|
|
|
// Returns the Perkeep blobref for a DOM blob (different from Perkeep blob) using the currently recommended hash function. This function currently only works within workers.
|
|
// @param {Blob} blob
|
|
// @returns {!string}
|
|
cam.blob.refFromDOMBlob = function(blob) {
|
|
if (!goog.global.FileReaderSync) {
|
|
// TODO(aa): If necessary, we can also implement this using FileReader for use on the main thread. But beware that should not be done for very large objects without checking the effect on framerate carefully.
|
|
throw new Error('FileReaderSync not available. Perhaps we are on the main thread?');
|
|
}
|
|
|
|
var fr = new FileReaderSync();
|
|
var hash = cam.blob.createHash();
|
|
var chunkSize = 1024 * 1024;
|
|
for (var start = 0; start < blob.size; start += chunkSize) {
|
|
var end = Math.min(start + chunkSize, blob.size);
|
|
var slice = blob.slice(start, end);
|
|
hash.update(new Uint8Array(fr.readAsArrayBuffer(slice)));
|
|
}
|
|
|
|
return cam.blob.refFromHash(hash);
|
|
};
|
|
|
|
// Creates an instance of the currently recommened hash function.
|
|
// @return {!goog.crypt.Hash'}
|
|
cam.blob.createHash = function() {
|
|
return new goog.crypt.Sha224();
|
|
};
|