fix: lower lookbehind size to needleLength - 1 (#175)

gurgunday · web-flow · commit eece7f38a0db · 2024-12-02T21:34:26.000+01:00
* lower lookbehind length

* use needleLastCharIndex
diff --git a/deps/streamsearch/sbmh.js b/deps/streamsearch/sbmh.js
@@ -40,6 +40,7 @@ function SBMH (needle) {
   }
 
   const needleLength = needle.length
+  const needleLastCharIndex = needleLength - 1
 
   if (needleLength === 0) {
     throw new Error('The needle cannot be an empty String/Buffer.')
@@ -58,12 +59,12 @@ function SBMH (needle) {
   this._needle = needle
   this._bufpos = 0
 
-  this._lookbehind = Buffer.alloc(needleLength)
+  this._lookbehind = Buffer.alloc(needleLastCharIndex)
 
   // Populate occurrence table with analysis of the needle,
   // ignoring last letter.
-  for (var i = 0; i < needleLength - 1; ++i) { // eslint-disable-line no-var
-    this._occ[needle[i]] = needleLength - 1 - i
+  for (var i = 0; i < needleLastCharIndex; ++i) { // eslint-disable-line no-var
+    this._occ[needle[i]] = needleLastCharIndex - i
   }
 }
 inherits(SBMH, EventEmitter)
diff --git a/test/streamsearch.test.js b/test/streamsearch.test.js
@@ -244,7 +244,7 @@ test('streamsearch', async t => {
 
     const expected = [
       [false, Buffer.from('bar\r'), 0, 3],
-      [false, Buffer.from('\r\0\0'), 0, 1],
+      [false, Buffer.from('\r\0'), 0, 1],
       [false, Buffer.from('\n\r\nhello'), 0, 8]
     ]
     const needle = '\r\n\n'
@@ -339,7 +339,7 @@ test('streamsearch', async t => {
     t.plan(13)
 
     const expected = [
-      [false, Buffer.from('\n\n\0'), 0, 1],
+      [false, Buffer.from('\n\n'), 0, 1],
       [true, undefined, undefined, undefined],
       [false, Buffer.from('\r\nhello'), 1, 7]
     ]
@@ -374,8 +374,8 @@ test('streamsearch', async t => {
 
     const expected = [
       [false, Buffer.from('bar\r'), 0, 3],
-      [false, Buffer.from('\r\n\0'), 0, 2],
-      [false, Buffer.from('\r\n\0'), 0, 1],
+      [false, Buffer.from('\r\n'), 0, 2],
+      [false, Buffer.from('\r\n'), 0, 1],
       [false, Buffer.from('hello'), 0, 5]
     ]
     const needle = '\r\n\n'

Original file line number	Diff line number	Diff line change
`@@ -40,6 +40,7 @@ function SBMH (needle) {`
`40`	`40`	`}`
`41`	`41`
`42`	`42`	`const needleLength = needle.length`
	`43`	`+ const needleLastCharIndex = needleLength - 1`
`43`	`44`
`44`	`45`	`if (needleLength === 0) {`
`45`	`46`	`throw new Error('The needle cannot be an empty String/Buffer.')`
`@@ -58,12 +59,12 @@ function SBMH (needle) {`
`58`	`59`	`this._needle = needle`
`59`	`60`	`this._bufpos = 0`
`60`	`61`
`61`		`- this._lookbehind = Buffer.alloc(needleLength)`
	`62`	`+ this._lookbehind = Buffer.alloc(needleLastCharIndex)`
`62`	`63`
`63`	`64`	`// Populate occurrence table with analysis of the needle,`
`64`	`65`	`// ignoring last letter.`
`65`		`- for (var i = 0; i < needleLength - 1; ++i) { // eslint-disable-line no-var`
`66`		`- this._occ[needle[i]] = needleLength - 1 - i`
	`66`	`+ for (var i = 0; i < needleLastCharIndex; ++i) { // eslint-disable-line no-var`
	`67`	`+ this._occ[needle[i]] = needleLastCharIndex - i`
`67`	`68`	`}`
`68`	`69`	`}`
`69`	`70`	`inherits(SBMH, EventEmitter)`