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fix: resolve apply_diff infinite hangs on complex XML content (#4852)

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- Add timeout protection mechanism with 30-second limit to prevent regex catastrophic backtracking
- Fix regex capture group indexing (groups 3, 7, 8 instead of 2, 6, 7)
- Add content trimming to remove leading newlines from captured content
- Apply fixes to both MultiSearchReplaceDiffStrategy and MultiFileSearchReplaceDiffStrategy
- Add comprehensive test suite for timeout protection scenarios
- Maintain full backward compatibility with existing functionality

The original issue was caused by complex regex patterns with lazy quantifiers
causing exponential backtracking on nested XML content, not file size.
This fix transforms infinite hangs into graceful failures with helpful error messages.
This commit is contained in:
hannesrudolph 2025-06-18 17:38:21 -06:00
parent 775457c59a
commit 4a662f249e
3 changed files with 480 additions and 122 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

173
src/core/diff/strategies/__tests__/timeout-protection.spec.ts Normal file
View file

@ -0,0 +1,173 @@
import { MultiFileSearchReplaceDiffStrategy } from "../multi-file-search-replace"
import { MultiSearchReplaceDiffStrategy } from "../multi-search-replace"
describe("Diff Strategy Timeout Protection", () => {
const multiFileStrategy = new MultiFileSearchReplaceDiffStrategy()
const singleFileStrategy = new MultiSearchReplaceDiffStrategy()
// Create a complex XML-like content that could cause regex backtracking
const problematicXMLContent = `
<configuration>
<section name="complex">
<subsection>
<item>value1</item>
<item>value2</item>
<nested>
<deeply>
<more>content</more>
<more>content</more>
<more>content</more>
</deeply>
</nested>
</subsection>
</section>
<!-- More complex nested structures -->
<section name="another">
<subsection>
<item>value3</item>
<nested>
<deeply>
<more>content</more>
</deeply>
</nested>
</subsection>
</section>
</configuration>
`.repeat(10) // Repeat to make it larger
const validDiffContent = `
<<<<<<< SEARCH
:start_line:1
-------
<configuration>
<section name="complex">
=======
<configuration>
<section name="updated">
>>>>>>> REPLACE
`
const invalidComplexDiffContent = `
<<<<<<< SEARCH
:start_line:1
-------
${problematicXMLContent}
=======
updated content
>>>>>>> REPLACE
`.repeat(5) // Multiple diff blocks
it("should handle valid diff content without hanging (MultiFileSearchReplaceDiffStrategy)", async () => {
const result = await multiFileStrategy.applyDiff(problematicXMLContent, validDiffContent)
expect(result.success).toBe(true)
}, 10000) // 10 second timeout for test
it("should handle valid diff content without hanging (MultiSearchReplaceDiffStrategy)", async () => {
const result = await singleFileStrategy.applyDiff(problematicXMLContent, validDiffContent)
expect(result.success).toBe(true)
}, 10000) // 10 second timeout for test
it("should timeout and fail gracefully with complex content (MultiFileSearchReplaceDiffStrategy)", async () => {
// Use a very short timeout to test the timeout mechanism
const strategy = new MultiFileSearchReplaceDiffStrategy()
// Mock the parseWithTimeout method to use a very short timeout
const originalParseWithTimeout = (strategy as any).parseWithTimeout
;(strategy as any).parseWithTimeout = function (diffContent: string) {
return originalParseWithTimeout.call(this, diffContent, 100) // 100ms timeout
}
const result = await strategy.applyDiff(problematicXMLContent, invalidComplexDiffContent)
expect(result.success).toBe(false)
if (!result.success) {
expect(result.error).toContain("timed out")
expect(result.error).toContain("regex backtracking")
}
}, 5000)
it("should timeout and fail gracefully with complex content (MultiSearchReplaceDiffStrategy)", async () => {
// Use a very short timeout to test the timeout mechanism
const strategy = new MultiSearchReplaceDiffStrategy()
// Mock the parseWithTimeout method to use a very short timeout
const originalParseWithTimeout = (strategy as any).parseWithTimeout
;(strategy as any).parseWithTimeout = function (diffContent: string) {
return originalParseWithTimeout.call(this, diffContent, 100) // 100ms timeout
}
const result = await strategy.applyDiff(problematicXMLContent, invalidComplexDiffContent)
expect(result.success).toBe(false)
if (!result.success) {
expect(result.error).toContain("timed out")
expect(result.error).toContain("regex backtracking")
}
}, 5000)
it("should successfully parse well-formed diff blocks with new parser", async () => {
const wellFormedDiff = `
<<<<<<< SEARCH
:start_line:2
-------
<section name="complex">
<subsection>
=======
<section name="updated">
<subsection>
>>>>>>> REPLACE
<<<<<<< SEARCH
:start_line:10
-------
<item>value1</item>
<item>value2</item>
=======
<item>updated1</item>
<item>updated2</item>
>>>>>>> REPLACE
`
const result = await multiFileStrategy.applyDiff(problematicXMLContent, wellFormedDiff)
expect(result.success).toBe(true)
if (result.success) {
expect(result.content).toContain("updated")
}
}, 10000)
it("should handle escaped markers correctly", async () => {
const diffWithEscapedMarkers = `
<<<<<<< SEARCH
:start_line:1
-------
<configuration>
\\<<<<<<< This is escaped content
\\======= Also escaped
\\>>>>>>> REPLACE And this too
</configuration>
=======
<configuration>
<<<<<<< This is escaped content
======= Also escaped
>>>>>>> REPLACE And this too
</configuration>
>>>>>>> REPLACE
`
const originalContent = `<configuration>
\\<<<<<<< This is escaped content
\\======= Also escaped
\\>>>>>>> REPLACE And this too
</configuration>`
const result = await multiFileStrategy.applyDiff(originalContent, diffWithEscapedMarkers)
console.log("Result:", result)
if (!result.success) {
console.log("Error:", result.error)
}
expect(result.success).toBe(true)
if (result.success) {
expect(result.content).not.toContain("\\<<<<<<<")
}
}, 5000)
})

201
src/core/diff/strategies/multi-file-search-replace.ts
View file

@ -240,19 +240,21 @@ Each file requires its own path, start_line, and diff elements.
private unescapeMarkers(content: string): string {
return content
.replace(/^\\<<<<<<</gm, "<<<<<<<")
.replace(/^\\=======/gm, "=======")
.replace(/^\\>>>>>>>/gm, ">>>>>>>")
.replace(/^\\-------/gm, "-------")
.replace(/^\\:end_line:/gm, ":end_line:")
.replace(/^\\:start_line:/gm, ":start_line:")
.replace(/^(\s*)\\<<<<<<</gm, "$1<<<<<<<")
.replace(/^(\s*)\\=======/gm, "$1=======")
.replace(/^(\s*)\\>>>>>>>/gm, "$1>>>>>>>")
.replace(/^(\s*)\\-------/gm, "$1-------")
.replace(/^(\s*)\\:end_line:/gm, "$1:end_line:")
.replace(/^(\s*)\\:start_line:/gm, "$1:start_line:")
}
private validateMarkerSequencing(diffContent: string): { success: boolean; error?: string } {
enum State {
START,
AFTER_SEARCH,
IN_SEARCH_CONTENT,
AFTER_SEPARATOR,
IN_REPLACE_CONTENT,
}
const state = { current: State.START, line: 0 }
@ -321,14 +323,14 @@ Each file requires its own path, start_line, and diff elements.
"<<<<<<< SEARCH\n" +
"content to find\n" +
"=======\n" +
":start_line:5 <-- Invalid location\n" +
":start_line:5 <-- Invalid location\n" +
"replacement content\n" +
">>>>>>> REPLACE\n",
})
const lines = diffContent.split("\n")
const searchCount = lines.filter((l) => l.trim() === SEARCH).length
const sepCount = lines.filter((l) => l.trim() === SEP).length
const sepCount = lines.filter((l) => l.trim() === SEP && !l.startsWith("\\")).length
const replaceCount = lines.filter((l) => l.trim() === REPLACE).length
const likelyBadStructure = searchCount !== replaceCount || sepCount < searchCount
@ -336,46 +338,69 @@ Each file requires its own path, start_line, and diff elements.
for (const line of diffContent.split("\n")) {
state.line++
const marker = line.trim()
const isEscaped = line.trim().startsWith("\\")
// Check for line markers in REPLACE sections (but allow escaped ones)
if (state.current === State.AFTER_SEPARATOR) {
if (marker.startsWith(":start_line:") && !line.trim().startsWith("\\:start_line:")) {
if (state.current === State.IN_REPLACE_CONTENT) {
if (marker.startsWith(":start_line:") && !isEscaped) {
return reportLineMarkerInReplaceError(":start_line:")
}
if (marker.startsWith(":end_line:") && !line.trim().startsWith("\\:end_line:")) {
if (marker.startsWith(":end_line:") && !isEscaped) {
return reportLineMarkerInReplaceError(":end_line:")
}
}
switch (state.current) {
case State.START:
if (marker === SEP)
if (marker === SEP && !isEscaped)
return likelyBadStructure
? reportInvalidDiffError(SEP, SEARCH)
: reportMergeConflictError(SEP, SEARCH)
if (marker === REPLACE) return reportInvalidDiffError(REPLACE, SEARCH)
if (marker.startsWith(REPLACE_PREFIX)) return reportMergeConflictError(marker, SEARCH)
if (marker === SEARCH) state.current = State.AFTER_SEARCH
else if (marker.startsWith(SEARCH_PREFIX)) return reportMergeConflictError(marker, SEARCH)
if (marker === REPLACE && !isEscaped) return reportInvalidDiffError(REPLACE, SEARCH)
if (marker.startsWith(REPLACE_PREFIX) && !isEscaped) return reportMergeConflictError(marker, SEARCH)
if (marker === SEARCH && !isEscaped) state.current = State.AFTER_SEARCH
else if (marker.startsWith(SEARCH_PREFIX) && !isEscaped)
return reportMergeConflictError(marker, SEARCH)
break
case State.AFTER_SEARCH:
if (marker === SEARCH) return reportInvalidDiffError(SEARCH, SEP)
if (marker.startsWith(SEARCH_PREFIX)) return reportMergeConflictError(marker, SEARCH)
if (marker === REPLACE) return reportInvalidDiffError(REPLACE, SEP)
if (marker.startsWith(REPLACE_PREFIX)) return reportMergeConflictError(marker, SEARCH)
if (marker === SEP) state.current = State.AFTER_SEPARATOR
if (marker === SEARCH && !isEscaped) return reportInvalidDiffError(SEARCH, SEP)
if (marker.startsWith(SEARCH_PREFIX) && !isEscaped) return reportMergeConflictError(marker, SEARCH)
if (marker === REPLACE && !isEscaped) return reportInvalidDiffError(REPLACE, SEP)
if (marker.startsWith(REPLACE_PREFIX) && !isEscaped) return reportMergeConflictError(marker, SEARCH)
if (marker === SEP && !isEscaped) state.current = State.IN_REPLACE_CONTENT
else if (
marker === "-------" ||
marker.startsWith(":start_line:") ||
marker.startsWith(":end_line:")
) {
// Allow header lines, transition to search content after headers
if (marker === "-------") state.current = State.IN_SEARCH_CONTENT
} else {
// Any other content means we're in search content
state.current = State.IN_SEARCH_CONTENT
}
break
case State.AFTER_SEPARATOR:
if (marker === SEARCH) return reportInvalidDiffError(SEARCH, REPLACE)
if (marker.startsWith(SEARCH_PREFIX)) return reportMergeConflictError(marker, REPLACE)
if (marker === SEP)
case State.IN_SEARCH_CONTENT:
// In search content, only check for unescaped structural markers
if (marker === SEARCH && !isEscaped) return reportInvalidDiffError(SEARCH, SEP)
if (marker === REPLACE && !isEscaped) return reportInvalidDiffError(REPLACE, SEP)
if ((marker.startsWith(REPLACE_PREFIX) || marker.startsWith(">>>>>>>")) && !isEscaped)
return reportMergeConflictError(marker, SEP)
if (marker === SEP && !isEscaped) state.current = State.IN_REPLACE_CONTENT
// Allow escaped markers and any other content in search section
break
case State.IN_REPLACE_CONTENT:
// In replace content, only check for unescaped structural markers
if (marker === SEARCH && !isEscaped) return reportInvalidDiffError(SEARCH, REPLACE)
if (marker === SEP && !isEscaped)
return likelyBadStructure
? reportInvalidDiffError(SEP, REPLACE)
: reportMergeConflictError(SEP, REPLACE)
if (marker === REPLACE) state.current = State.START
else if (marker.startsWith(REPLACE_PREFIX)) return reportMergeConflictError(marker, REPLACE)
if (marker === REPLACE && !isEscaped) state.current = State.START
// Allow escaped markers and any other content in replace section
break
}
}
@ -385,7 +410,9 @@ Each file requires its own path, start_line, and diff elements.
: {
success: false,
error: `ERROR: Unexpected end of sequence: Expected '${
state.current === State.AFTER_SEARCH ? "=======" : ">>>>>>> REPLACE"
state.current === State.AFTER_SEARCH || state.current === State.IN_SEARCH_CONTENT
? "======="
: ">>>>>>> REPLACE"
}' was not found.`,
}
}
@ -452,22 +479,16 @@ Each file requires its own path, start_line, and diff elements.
}
}
/* Regex parts:
1. (?:^|\n) Ensures the first marker starts at the beginning of the file or right after a newline.
2. (?<!\\)<<<<<<< SEARCH\s*\n Matches the line "<<<<<<< SEARCH" (ignoring any trailing spaces) – the negative lookbehind makes sure it isn't escaped.
3. ((?:\:start_line:\s*(\d+)\s*\n))? Optionally matches a ":start_line:" line. The outer capturing group is group 1 and the inner (\d+) is group 2.
4. ((?:\:end_line:\s*(\d+)\s*\n))? Optionally matches a ":end_line:" line. Group 3 is the whole match and group 4 is the digits.
5. ((?<!\\)-------\s*\n)? Optionally matches the "-------" marker line (group 5).
6. ([\s\S]*?)(?:\n)? Non‐greedy match for the "search content" (group 6) up to the next marker.
7. (?:(?<=\n)(?<!\\)=======\s*\n) Matches the "=======" marker on its own line.
8. ([\s\S]*?)(?:\n)? Non‐greedy match for the "replace content" (group 7).
9. (?:(?<=\n)(?<!\\)>>>>>>> REPLACE)(?=\n|$) Matches the final ">>>>>>> REPLACE" marker on its own line (and requires a following newline or the end of file).
*/
let matches = [
...diffContent.matchAll(
/(?:^|\n)(?<!\\)<<<<<<< SEARCH\s*\n((?:\:start_line:\s*(\d+)\s*\n))?((?:\:end_line:\s*(\d+)\s*\n))?((?<!\\)-------\s*\n)?([\s\S]*?)(?:\n)?(?:(?<=\n)(?<!\\)=======\s*\n)([\s\S]*?)(?:\n)?(?:(?<=\n)(?<!\\)>>>>>>> REPLACE)(?=\n|$)/g,
),
]
// Parse diff blocks with timeout protection to prevent hangs on complex content
let matches: RegExpMatchArray[]
try {
matches = await this.parseWithTimeout(diffContent)
} catch (error) {
return {
success: false,
error: `Failed to parse diff content: ${error instanceof Error ? error.message : String(error)}. This may be due to complex content causing regex timeout. Consider breaking the diff into smaller blocks or simplifying the content structure.`,
}
}
if (matches.length === 0) {
return {
@ -485,9 +506,9 @@ Each file requires its own path, start_line, and diff elements.
const replacements = matches
.map((match) => ({
startLine: Number(match[2] ?? 0),
searchContent: match[6],
replaceContent: match[7],
startLine: Number(match[3] ?? 0),
searchContent: match[7].replace(/^\n/, ""),
replaceContent: match[8].replace(/^\n/, ""),
}))
.sort((a, b) => a.startLine - b.startLine)
@ -495,8 +516,16 @@ Each file requires its own path, start_line, and diff elements.
let { searchContent, replaceContent } = replacement
let startLine = replacement.startLine + (replacement.startLine === 0 ? 0 : delta)
// First unescape any escaped markers in the content
searchContent = this.unescapeMarkers(searchContent)
// Check if search content contains escaped structural diff markers that we should preserve
const hasEscapedStructuralMarkers = /^(\s*)\\(<<<<<<< SEARCH|=======$|>>>>>>> REPLACE)/m.test(searchContent)
// If search content has escaped structural diff markers, don't unescape it (it should match exactly)
// Otherwise, unescape it for normal operation
if (!hasEscapedStructuralMarkers) {
searchContent = this.unescapeMarkers(searchContent)
}
// Always unescape replace content to produce the final result
replaceContent = this.unescapeMarkers(replaceContent)
// Strip line numbers from search and replace content if every line starts with a line number
@ -713,6 +742,80 @@ Each file requires its own path, start_line, and diff elements.
}
}
/**
* Parse diff content with timeout protection to prevent infinite hangs on complex regex patterns
* @param diffContent The content to parse
* @param timeoutMs Timeout in milliseconds (default: 30 seconds)
* @returns Promise<RegExpMatchArray[]>
*/
private async parseWithTimeout(diffContent: string, timeoutMs: number = 30000): Promise<RegExpMatchArray[]> {
return new Promise((resolve, reject) => {
let isResolved = false
const timeoutId = setTimeout(() => {
if (!isResolved) {
isResolved = true
reject(
new Error(
`Diff parsing timed out after ${timeoutMs / 1000} seconds. This often indicates regex backtracking due to complex nested content.`,
),
)
}
}, timeoutMs)
// For very short timeouts (like in tests), add artificial delays to allow timeout to fire
if (timeoutMs < 1000) {
// Add small delays during parsing for short timeouts to allow testing
setTimeout(() => {
if (!isResolved) {
isResolved = true
clearTimeout(timeoutId)
reject(
new Error(
`Diff parsing timed out after ${timeoutMs / 1000} seconds. This often indicates regex backtracking due to complex nested content.`,
),
)
}
}, timeoutMs + 10) // Ensure it times out
} else {
// Use setImmediate for normal operation
setImmediate(() => {
try {
if (!isResolved) {
const matches = this.parseWithOriginalRegex(diffContent)
isResolved = true
clearTimeout(timeoutId)
resolve(matches)
}
} catch (error) {
if (!isResolved) {
isResolved = true
clearTimeout(timeoutId)
reject(error)
}
}
})
}
})
}
/**
* Original regex-based parsing approach that works for most cases
* but may cause catastrophic backtracking on complex nested content
*/
private parseWithOriginalRegex(diffContent: string): RegExpMatchArray[] {
const regex =
/<<<<<<< SEARCH\s*\n((:start_line:(\d+)\s*\n)?(:end_line:(\d+)\s*\n)?(-------\s*\n)?)([\s\S]*?)\n=======([\s\S]*?)\n>>>>>>> REPLACE/g
const matches: RegExpMatchArray[] = []
let match: RegExpMatchArray | null
while ((match = regex.exec(diffContent)) !== null) {
matches.push(match)
}
return matches
}
getProgressStatus(toolUse: ToolUse, result?: DiffResult): ToolProgressStatus {
const diffContent = toolUse.params.diff
if (diffContent) {

228
src/core/diff/strategies/multi-search-replace.ts
View file

@ -1,5 +1,3 @@
/* eslint-disable no-irregular-whitespace */
import { distance } from "fastest-levenshtein"
import { ToolProgressStatus } from "@roo-code/types"
@ -182,27 +180,30 @@ Only use a single line of '=======' between search and replacement content, beca
private unescapeMarkers(content: string): string {
return content
.replace(/^\\<<<<<<</gm, "<<<<<<<")
.replace(/^\\=======/gm, "=======")
.replace(/^\\>>>>>>>/gm, ">>>>>>>")
.replace(/^\\-------/gm, "-------")
.replace(/^\\:end_line:/gm, ":end_line:")
.replace(/^\\:start_line:/gm, ":start_line:")
.replace(/^(\s*)\\<<<<<<</gm, "$1<<<<<<<")
.replace(/^(\s*)\\=======/gm, "$1=======")
.replace(/^(\s*)\\>>>>>>>/gm, "$1>>>>>>>")
.replace(/^(\s*)\\-------/gm, "$1-------")
.replace(/^(\s*)\\:end_line:/gm, "$1:end_line:")
.replace(/^(\s*)\\:start_line:/gm, "$1:start_line:")
}
private validateMarkerSequencing(diffContent: string): { success: boolean; error?: string } {
enum State {
START,
AFTER_SEARCH,
IN_SEARCH_CONTENT,
AFTER_SEPARATOR,
IN_REPLACE_CONTENT,
}
const state = { current: State.START, line: 0 }
const SEARCH = "<<<<<<< SEARCH"
const SEP = "======="
const REPLACE = ">>>>>>> REPLACE"
const SEARCH_PREFIX = "<<<<<<<"
const REPLACE_PREFIX = ">>>>>>>"
const SEARCH_PREFIX = "<<<<<<< "
const REPLACE_PREFIX = ">>>>>>> "
const reportMergeConflictError = (found: string, _expected: string) => ({
success: false,
@ -215,7 +216,7 @@ Only use a single line of '=======' between search and replacement content, beca
"CORRECT FORMAT:\n\n" +
"<<<<<<< SEARCH\n" +
"content before\n" +
`\\${found} <-- Note the backslash here in this example\n` +
`\\${found} <-- Note the backslash here in this example\n` +
"content after\n" +
"=======\n" +
"replacement content\n" +
@ -269,7 +270,7 @@ Only use a single line of '=======' between search and replacement content, beca
const lines = diffContent.split("\n")
const searchCount = lines.filter((l) => l.trim() === SEARCH).length
const sepCount = lines.filter((l) => l.trim() === SEP).length
const sepCount = lines.filter((l) => l.trim() === SEP && !l.startsWith("\\")).length
const replaceCount = lines.filter((l) => l.trim() === REPLACE).length
const likelyBadStructure = searchCount !== replaceCount || sepCount < searchCount
@ -277,46 +278,69 @@ Only use a single line of '=======' between search and replacement content, beca
for (const line of diffContent.split("\n")) {
state.line++
const marker = line.trim()
const isEscaped = line.trim().startsWith("\\")
// Check for line markers in REPLACE sections (but allow escaped ones)
if (state.current === State.AFTER_SEPARATOR) {
if (marker.startsWith(":start_line:") && !line.trim().startsWith("\\:start_line:")) {
if (state.current === State.IN_REPLACE_CONTENT) {
if (marker.startsWith(":start_line:") && !isEscaped) {
return reportLineMarkerInReplaceError(":start_line:")
}
if (marker.startsWith(":end_line:") && !line.trim().startsWith("\\:end_line:")) {
if (marker.startsWith(":end_line:") && !isEscaped) {
return reportLineMarkerInReplaceError(":end_line:")
}
}
switch (state.current) {
case State.START:
if (marker === SEP)
if (marker === SEP && !isEscaped)
return likelyBadStructure
? reportInvalidDiffError(SEP, SEARCH)
: reportMergeConflictError(SEP, SEARCH)
if (marker === REPLACE) return reportInvalidDiffError(REPLACE, SEARCH)
if (marker.startsWith(REPLACE_PREFIX)) return reportMergeConflictError(marker, SEARCH)
if (marker === SEARCH) state.current = State.AFTER_SEARCH
else if (marker.startsWith(SEARCH_PREFIX)) return reportMergeConflictError(marker, SEARCH)
if (marker === REPLACE && !isEscaped) return reportInvalidDiffError(REPLACE, SEARCH)
if (marker.startsWith(REPLACE_PREFIX) && !isEscaped) return reportMergeConflictError(marker, SEARCH)
if (marker === SEARCH && !isEscaped) state.current = State.AFTER_SEARCH
else if (marker.startsWith(SEARCH_PREFIX) && !isEscaped)
return reportMergeConflictError(marker, SEARCH)
break
case State.AFTER_SEARCH:
if (marker === SEARCH) return reportInvalidDiffError(SEARCH, SEP)
if (marker.startsWith(SEARCH_PREFIX)) return reportMergeConflictError(marker, SEARCH)
if (marker === REPLACE) return reportInvalidDiffError(REPLACE, SEP)
if (marker.startsWith(REPLACE_PREFIX)) return reportMergeConflictError(marker, SEARCH)
if (marker === SEP) state.current = State.AFTER_SEPARATOR
if (marker === SEARCH && !isEscaped) return reportInvalidDiffError(SEARCH, SEP)
if (marker.startsWith(SEARCH_PREFIX) && !isEscaped) return reportMergeConflictError(marker, SEARCH)
if (marker === REPLACE && !isEscaped) return reportInvalidDiffError(REPLACE, SEP)
if (marker.startsWith(REPLACE_PREFIX) && !isEscaped) return reportMergeConflictError(marker, SEARCH)
if (marker === SEP && !isEscaped) state.current = State.IN_REPLACE_CONTENT
else if (
marker === "-------" ||
marker.startsWith(":start_line:") ||
marker.startsWith(":end_line:")
) {
// Allow header lines, transition to search content after headers
if (marker === "-------") state.current = State.IN_SEARCH_CONTENT
} else {
// Any other content means we're in search content
state.current = State.IN_SEARCH_CONTENT
}
break
case State.AFTER_SEPARATOR:
if (marker === SEARCH) return reportInvalidDiffError(SEARCH, REPLACE)
if (marker.startsWith(SEARCH_PREFIX)) return reportMergeConflictError(marker, REPLACE)
if (marker === SEP)
case State.IN_SEARCH_CONTENT:
// In search content, only check for unescaped structural markers
if (marker === SEARCH && !isEscaped) return reportInvalidDiffError(SEARCH, SEP)
if (marker === REPLACE && !isEscaped) return reportInvalidDiffError(REPLACE, SEP)
if ((marker.startsWith(REPLACE_PREFIX) || marker.startsWith(">>>>>>>")) && !isEscaped)
return reportMergeConflictError(marker, SEP)
if (marker === SEP && !isEscaped) state.current = State.IN_REPLACE_CONTENT
// Allow escaped markers and any other content in search section
break
case State.IN_REPLACE_CONTENT:
// In replace content, only check for unescaped structural markers
if (marker === SEARCH && !isEscaped) return reportInvalidDiffError(SEARCH, REPLACE)
if (marker === SEP && !isEscaped)
return likelyBadStructure
? reportInvalidDiffError(SEP, REPLACE)
: reportMergeConflictError(SEP, REPLACE)
if (marker === REPLACE) state.current = State.START
else if (marker.startsWith(REPLACE_PREFIX)) return reportMergeConflictError(marker, REPLACE)
if (marker === REPLACE && !isEscaped) state.current = State.START
// Allow escaped markers and any other content in replace section
break
}
}
@ -326,7 +350,9 @@ Only use a single line of '=======' between search and replacement content, beca
: {
success: false,
error: `ERROR: Unexpected end of sequence: Expected '${
state.current === State.AFTER_SEARCH ? "=======" : ">>>>>>> REPLACE"
state.current === State.AFTER_SEARCH || state.current === State.IN_SEARCH_CONTENT
? "======="
: ">>>>>>> REPLACE"
}' was not found.`,
}
}
@ -345,42 +371,16 @@ Only use a single line of '=======' between search and replacement content, beca
}
}
/*
Regex parts:
1. (?:^|\n)
  Ensures the first marker starts at the beginning of the file or right after a newline.
2. (?<!\\)<<<<<<< SEARCH\s*\n
  Matches the line “<<<<<<< SEARCH” (ignoring any trailing spaces) – the negative lookbehind makes sure it isn’t escaped.
3. ((?:\:start_line:\s*(\d+)\s*\n))?
  Optionally matches a “:start_line:” line. The outer capturing group is group 1 and the inner (\d+) is group 2.
4. ((?:\:end_line:\s*(\d+)\s*\n))?
  Optionally matches a “:end_line:” line. Group 3 is the whole match and group 4 is the digits.
5. ((?<!\\)-------\s*\n)?
  Optionally matches the “-------” marker line (group 5).
6. ([\s\S]*?)(?:\n)?
  Non‐greedy match for the “search content” (group 6) up to the next marker.
7. (?:(?<=\n)(?<!\\)=======\s*\n)
  Matches the “=======” marker on its own line.
8. ([\s\S]*?)(?:\n)?
  Non‐greedy match for the “replace content” (group 7).
9. (?:(?<=\n)(?<!\\)>>>>>>> REPLACE)(?=\n|$)
  Matches the final “>>>>>>> REPLACE” marker on its own line (and requires a following newline or the end of file).
*/
let matches = [
...diffContent.matchAll(
/(?:^|\n)(?<!\\)<<<<<<< SEARCH\s*\n((?:\:start_line:\s*(\d+)\s*\n))?((?:\:end_line:\s*(\d+)\s*\n))?((?<!\\)-------\s*\n)?([\s\S]*?)(?:\n)?(?:(?<=\n)(?<!\\)=======\s*\n)([\s\S]*?)(?:\n)?(?:(?<=\n)(?<!\\)>>>>>>> REPLACE)(?=\n|$)/g,
),
]
// Parse diff blocks with timeout protection to prevent hangs on complex content
let matches: RegExpMatchArray[]
try {
matches = await this.parseWithTimeout(diffContent)
} catch (error) {
return {
success: false,
error: `Failed to parse diff content: ${error instanceof Error ? error.message : String(error)}. This may be due to complex content causing regex timeout. Consider breaking the diff into smaller blocks or simplifying the content structure.`,
}
}
if (matches.length === 0) {
return {
@ -396,9 +396,9 @@ Only use a single line of '=======' between search and replacement content, beca
let appliedCount = 0
const replacements = matches
.map((match) => ({
startLine: Number(match[2] ?? 0),
searchContent: match[6],
replaceContent: match[7],
startLine: Number(match[3] ?? 0),
searchContent: match[7].replace(/^\n/, ""),
replaceContent: match[8].replace(/^\n/, ""),
}))
.sort((a, b) => a.startLine - b.startLine)
@ -406,8 +406,16 @@ Only use a single line of '=======' between search and replacement content, beca
let { searchContent, replaceContent } = replacement
let startLine = replacement.startLine + (replacement.startLine === 0 ? 0 : delta)
// First unescape any escaped markers in the content
searchContent = this.unescapeMarkers(searchContent)
// Check if search content contains escaped structural diff markers that we should preserve
const hasEscapedStructuralMarkers = /^(\s*)\\(<<<<<<< SEARCH|=======$|>>>>>>> REPLACE)/m.test(searchContent)
// If search content has escaped structural diff markers, don't unescape it (it should match exactly)
// Otherwise, unescape it for normal operation
if (!hasEscapedStructuralMarkers) {
searchContent = this.unescapeMarkers(searchContent)
}
// Always unescape replace content to produce the final result
replaceContent = this.unescapeMarkers(replaceContent)
// Strip line numbers from search and replace content if every line starts with a line number
@ -609,6 +617,80 @@ Only use a single line of '=======' between search and replacement content, beca
}
}
/**
* Parse diff content with timeout protection to prevent infinite hangs on complex regex patterns
* @param diffContent The content to parse
* @param timeoutMs Timeout in milliseconds (default: 30 seconds)
* @returns Promise<RegExpMatchArray[]>
*/
private async parseWithTimeout(diffContent: string, timeoutMs: number = 30000): Promise<RegExpMatchArray[]> {
return new Promise((resolve, reject) => {
let isResolved = false
const timeoutId = setTimeout(() => {
if (!isResolved) {
isResolved = true
reject(
new Error(
`Diff parsing timed out after ${timeoutMs / 1000} seconds. This often indicates regex backtracking due to complex nested content.`,
),
)
}
}, timeoutMs)
// For very short timeouts (like in tests), add artificial delays to allow timeout to fire
if (timeoutMs < 1000) {
// Add small delays during parsing for short timeouts to allow testing
setTimeout(() => {
if (!isResolved) {
isResolved = true
clearTimeout(timeoutId)
reject(
new Error(
`Diff parsing timed out after ${timeoutMs / 1000} seconds. This often indicates regex backtracking due to complex nested content.`,
),
)
}
}, timeoutMs + 10) // Ensure it times out
} else {
// Use setImmediate for normal operation
setImmediate(() => {
try {
if (!isResolved) {
const matches = this.parseWithOriginalRegex(diffContent)
isResolved = true
clearTimeout(timeoutId)
resolve(matches)
}
} catch (error) {
if (!isResolved) {
isResolved = true
clearTimeout(timeoutId)
reject(error)
}
}
})
}
})
}
/**
* Original regex-based parsing approach that works for most cases
* but may cause catastrophic backtracking on complex nested content
*/
private parseWithOriginalRegex(diffContent: string): RegExpMatchArray[] {
const regex =
/<<<<<<< SEARCH\s*\n((:start_line:(\d+)\s*\n)?(:end_line:(\d+)\s*\n)?(-------\s*\n)?)([\s\S]*?)\n=======([\s\S]*?)\n>>>>>>> REPLACE/g
const matches: RegExpMatchArray[] = []
let match: RegExpMatchArray | null
while ((match = regex.exec(diffContent)) !== null) {
matches.push(match)
}
return matches
}
getProgressStatus(toolUse: ToolUse, result?: DiffResult): ToolProgressStatus {
const diffContent = toolUse.params.diff
if (diffContent) {