Added buffer search algorithm to find signature in hex format

JackRKelly · Dec 22, 2020 · 16344b6 · 16344b6
1 parent 008f023
commit 16344b6
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Showing 2 changed files with 23 additions and 10 deletions.
diff --git a/src/reader.ts b/src/reader.ts
@@ -121,11 +121,26 @@ export class Reader {
  }
 
  hasSignature(signature: LESignature): boolean {
- return this.buffer.includes(signature, this.offset, "hex");
+ let cursor = this.offset;
+ while (this.buffer.readUInt32LE(cursor) !== signature) {
+ cursor += 1;
+ if (cursor + 4 > this.buffer.length) {
+ return false;
+ }
+ }
+ return true;
  }
 
  findSignature(signature: LESignature): number {
- return this.buffer.indexOf(signature, this.offset, "hex");
+ let cursor = this.offset;
+ while (this.buffer.readUInt32LE(cursor) !== signature) {
+ cursor += 1;
+ if (cursor + 4 > this.buffer.length) {
+ cursor = -1;
+ break;
+ }
+ }
+ return cursor;
  }
 
  setOffset(offset: number): void {
@@ -359,10 +374,8 @@ export class Reader {
  this.offset = 0;
  this.buffer = zip;
  //Determine endianess on reader initialization.
- if (
- zip.readUInt32LE() ===
- Buffer.from(LESignature.LocalFile, "hex").readUInt32LE()
- ) {
+
+ if (zip.readUInt32LE() === LESignature.LocalFile) {
  this.endian = Endian.Little;
  } else {
  this.endian = Endian.Big;

diff --git a/src/util.ts b/src/util.ts
@@ -4,10 +4,10 @@ export enum Endian {
 }
 
 export enum LESignature {
- LocalFile = "504b0304",
- DataDescriptor = "504b0708",
- CentralDirectory = "504b0102",
- EndCentralDirectory = "504b0506",
+ LocalFile = 0x04034b50,
+ DataDescriptor = 0x08074b50,
+ CentralDirectory = 0x02014b50,
+ EndCentralDirectory = 0x06054b50,
 }
 
 export enum OS {