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61 lines
1.7 KiB
61 lines
1.7 KiB
const web3Utils = require('web3-utils')
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/**
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* Writes data from the VM step to the in-memory
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* coverage map constructed by the Instrumenter.
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*/
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class DataCollector {
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constructor(instrumentationData={}){
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this.instrumentationData = instrumentationData;
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this.validOpcodes = {
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"PUSH1": true,
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}
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}
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/**
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* VM step event handler. Detects instrumentation hashes when they are pushed to the
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* top of the stack. This runs millions of times - trying to keep it fast.
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* @param {Object} info vm step info
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*/
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step(info){
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try {
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if (this.validOpcodes[info.opcode.name] && info.stack.length > 0){
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const idx = info.stack.length - 1;
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let hash = web3Utils.toHex(info.stack[idx]).toString();
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hash = this._normalizeHash(hash);
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if(this.instrumentationData[hash]){
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this.instrumentationData[hash].hits++;
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}
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}
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} catch (err) { /*Ignore*/ };
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}
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/**
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* Left-pads zero prefixed bytes 32 hashes to length 66. The '59' in the
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* comparison below is arbitrary. It provides a margin for recurring zeros
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* but prevents left-padding shorter irrelevant hashes (like fn sigs)
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*
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* @param {String} hash data hash from evm stack.
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* @return {String} 0x prefixed hash of length 66.
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*/
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_normalizeHash(hash){
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if (hash.length < 66 && hash.length > 59){
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hash = hash.slice(2);
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while(hash.length < 64) hash = '0' + hash;
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hash = '0x' + hash
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}
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return hash;
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}
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/**
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* Unit test helper
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* @param {Object} data Instrumenter.instrumentationData
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*/
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_setInstrumentationData(data){
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this.instrumentationData = data;
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}
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}
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module.exports = DataCollector; |