mirror of https://github.com/perkeep/perkeep.git
67 lines
2.4 KiB
JavaScript
67 lines
2.4 KiB
JavaScript
/*
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Copyright 2014 Google Inc.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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goog.provide('camlistore.blob');
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goog.require('goog.crypt');
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goog.require('goog.crypt.Sha1');
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// Returns the Camlistore blobref for hash object. The only supported hash function is currently sha1, but more might be added later.
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// @param {!goog.crypt.Hash} hash
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// @returns {!string}
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camlistore.blob.refFromHash = function(hash) {
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if (hash instanceof goog.crypt.Sha1) {
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return 'sha1-' + goog.crypt.byteArrayToHex(hash.digest());
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}
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throw new Error('Unsupported hash function type');
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};
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// Returns the Camlistore blobref for a string using the currently recommended hash function.
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// @param {!string} str
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// @returns {!string}
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camlistore.blob.refFromString = function(str) {
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var hash = camlistore.blob.createHash();
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hash.update(str);
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return camlistore.blob.refFromHash(hash);
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};
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// Returns the Camlistore blobref for a DOM blob (different from Camlistore blob) using the currently recommended hash function. This function currently only works within workers.
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// @param {Blob} blob
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// @returns {!string}
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camlistore.blob.refFromDOMBlob = function(blob) {
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if (!goog.global.FileReaderSync) {
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// 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.
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throw new Error('FileReaderSync not available. Perhaps we are on the main thread?');
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}
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var fr = new FileReaderSync();
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var hash = camlistore.blob.createHash();
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var chunkSize = 1024 * 1024;
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for (var start = 0; start < blob.size; start += chunkSize) {
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var end = Math.min(start + chunkSize, blob.size);
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var slice = blob.slice(start, end);
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hash.update(new Uint8Array(fr.readAsArrayBuffer(slice)));
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}
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return camlistore.blob.refFromHash(hash);
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};
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// Creates an instance of the currently recommened hash function.
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// @return {!goog.crypt.Hash'}
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camlistore.blob.createHash = function() {
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return new goog.crypt.Sha1();
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};
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