1 /* 2 * Copyright 2017, The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 const LAYER_TRACE_MAGIC_NUMBER = [0x09, 0x4c, 0x59, 0x52, 0x54, 0x52, 0x41, 0x43, 0x45] // .LYRTRACE 18 const WINDOW_TRACE_MAGIC_NUMBER = [0x09, 0x57, 0x49, 0x4e, 0x54, 0x52, 0x41, 0x43, 0x45] // .WINTRACE 19 20 function arrayEquals(a, b) { 21 if (a.length !== b.length) { 22 return false; 23 } 24 for (var i = 0; i < a.length; i++) { 25 if (a[i] != b[i]) { 26 return false; 27 } 28 } 29 return true; 30 } 31 32 function arrayStartsWith(array, prefix) { 33 return arrayEquals(array.slice(0, prefix.length), prefix); 34 } 35 36 /** buffer: Uint8Array */ 37 function detect(buffer) { 38 if (arrayStartsWith(buffer, LAYER_TRACE_MAGIC_NUMBER)) { 39 return 'layers_trace' 40 } 41 if (arrayStartsWith(buffer, WINDOW_TRACE_MAGIC_NUMBER)) { 42 return 'window_trace' 43 } 44 if (arrayStartsWith(buffer, [0x12])) { 45 // Because policy is empty, the first field in the dump is 2 currently. 46 // This might change. 47 return 'window_dump'; 48 } 49 if (arrayStartsWith(buffer, [0x0a])) { 50 // For now; window_dump might soon start with 0x0a too. 51 return 'layers_dump'; 52 } 53 } 54 55 export default detect; 56
