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Fix: Infinite recursion crash in wikitext parser #308

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Fix: Infinite recursion crash in wikitext parser #308

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0aa96cf
New: Implement recursion depth limit in Wikitext parser to prevent st…
sayeedjoy Dec 5, 2025
0956daf
Update app/src/main/java/org/nsh07/wikireader/parser/wikitextToAnnota…
sayeedjoy Dec 7, 2025
5e49c97
Update app/src/main/java/org/nsh07/wikireader/parser/wikitextToAnnota…
sayeedjoy Dec 7, 2025
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106 changes: 62 additions & 44 deletions app/src/main/java/org/nsh07/wikireader/parser/wikitextToAnnotatedString.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -44,6 +44,11 @@ import kotlin.text.Typography.nbsp
import kotlin.text.Typography.ndash

private const val MAGIC_SEP = "{{!}}"
private const val MAX_WIKITEXT_RECURSION_DEPTH = 64

private object WikitextParserState {
val recursionDepth: ThreadLocal<Int> = ThreadLocal.withInitial { 0 }
}

/**
* Converts Wikitext source code into an [AnnotatedString] that can be rendered by [androidx.compose.material3.Text]
Expand All @@ -57,39 +62,47 @@ fun String.toWikitextAnnotatedString(
inIndentCode: Boolean = false,
showRef: (String) -> Unit,
): AnnotatedString {
val hrChar = '─'
val input = this
var i = 0
var number = 1 // Count for numbered lists

var italic = false
var bold = false

val twas: String.() -> AnnotatedString = {
this.toWikitextAnnotatedString(
colorScheme,
typography,
loadPage,
fontSize,
showRef = showRef
)
val currentDepth = WikitextParserState.recursionDepth.get()
if (currentDepth >= MAX_WIKITEXT_RECURSION_DEPTH) {
// Fallback: avoid runaway recursion on pathological or malformed wikitext
return AnnotatedString(this)
}

val twasNoNewline: String.() -> AnnotatedString = {
this.toWikitextAnnotatedString(
colorScheme,
typography,
loadPage,
fontSize,
newLine = false,
showRef = showRef
)
}
WikitextParserState.recursionDepth.set(currentDepth + 1)
try {
val hrChar = '─'
val input = this
var i = 0
var number = 1 // Count for numbered lists

var italic = false
var bold = false

val twas: String.() -> AnnotatedString = {
this.toWikitextAnnotatedString(
colorScheme,
typography,
loadPage,
fontSize,
showRef = showRef
)
}

val twasNoNewline: String.() -> AnnotatedString = {
this.toWikitextAnnotatedString(
colorScheme,
typography,
loadPage,
fontSize,
newLine = false,
showRef = showRef
)
}

return buildAnnotatedString {
while (i < input.length) {
if (input[i] != '#') number = 1
when (input[i]) {
return buildAnnotatedString {
while (i < input.length) {
if (input[i] != '#') number = 1
when (input[i]) {
' ' ->
if ((getOrNull(i - 1) == '\n' || i == 0) && !inIndentCode) {
val curr = substring(i + 1).substringBefore('\n')
Expand Down Expand Up @@ -530,7 +543,7 @@ fun String.toWikitextAnnotatedString(
}

currSubstring.startsWith("{{abbr", ignoreCase = true) -> {
val curr = currSubstring.substringAfter('|').substringBefore('|')
val curr = currSubstring.substringAfter('|', "").substringBefore('|')
append(curr.twas())
}

Expand Down Expand Up @@ -575,19 +588,19 @@ fun String.toWikitextAnnotatedString(
}

currSubstring.startsWith("{{val", ignoreCase = true) -> {
val curr = currSubstring.substringAfter('|').substringBefore('|')
val curr = currSubstring.substringAfter('|', "").substringBefore('|')
append(curr.twas())
}

currSubstring.startsWith("{{var", ignoreCase = true) -> {
val curr = currSubstring.substringAfter('|')
val curr = currSubstring.substringAfter('|', "")
append("''$curr''".twas())
}

arrayOf("{{small", "{{smaller", "{{petit", "{{hw-small", "{{sma").any {
currSubstring.startsWith(it, ignoreCase = true)
} -> {
val curr = currSubstring.substringAfter('|')
val curr = currSubstring.substringAfter('|', "")
withStyle(SpanStyle(fontSize = (fontSize - 2).sp)) {
append(curr.twas())
}
Expand Down Expand Up @@ -652,7 +665,7 @@ fun String.toWikitextAnnotatedString(
}

currSubstring.startsWith("{{dfn", true) -> {
val curr = currSubstring.substringAfter('|')
val curr = currSubstring.substringAfter('|', "")
append("'''$curr'''".twas())
}

Expand Down Expand Up @@ -706,7 +719,8 @@ fun String.toWikitextAnnotatedString(
}

currSubstring.startsWith("{{format price", true) -> {
val curr = currSubstring.substringAfter('|').substringBefore('|')
val curr =
currSubstring.substringAfter('|', "").substringBefore('|')
append(
if (curr.contains('.')) curr.toDoubleOrNull()
?.formatToHumanReadable() ?: curr.twas()
Expand Down Expand Up @@ -838,13 +852,13 @@ fun String.toWikitextAnnotatedString(

currSubstring.startsWith("{{US$", true) -> {
if (currSubstring.contains('|')) {
val curr = currSubstring.substringAfter('|')
val curr = currSubstring.substringAfter('|', "")
append("US$${curr.twas()}")
} else append("US$")
}

currSubstring.startsWith("{{hatnote", ignoreCase = true) -> {
val curr = currSubstring.substringAfter('|').replace('\n', ' ')
val curr = currSubstring.substringAfter('|', "").replace('\n', ' ')
append("''$curr''".twas())
}

Expand Down Expand Up @@ -957,18 +971,18 @@ fun String.toWikitextAnnotatedString(
}

currSubstring.startsWith("{{rp", true) -> {
val curr = currSubstring.substringAfter('|')
val curr = currSubstring.substringAfter('|', "")
append("<sup>:$curr </sup>".twas())
}

currSubstring.startsWith("{{isbn", true) -> {
val curr = currSubstring.substringAfter('|').split('|')
val curr = currSubstring.substringAfter('|', "").split('|')
.filterNot { it.contains('=') }.joinToString()
append("[[ISBN]] $curr".twas())
}

currSubstring.startsWith("{{sfrac") -> {
val curr = currSubstring.substringAfter('|')
val curr = currSubstring.substringAfter('|', "")
val splitList = curr.split('|')
when (splitList.size) {
3 -> append("${splitList[0]}<sup>${splitList[1]}</sup>/<sub>${splitList[2]}</sub>".twas())
Expand All @@ -992,7 +1006,8 @@ fun String.toWikitextAnnotatedString(
}

currSubstring.startsWith("{{unichar", ignoreCase = true) -> {
val curr = currSubstring.substringAfter('|').substringBefore('|')
val curr =
currSubstring.substringAfter('|', "").substringBefore('|')
append("<code>U+$curr</code> ".twas())
try {
append(Character.toString(curr.toInt(16)))
Expand All @@ -1001,7 +1016,7 @@ fun String.toWikitextAnnotatedString(
}

currSubstring.startsWith("{{char", ignoreCase = true) -> {
append(currSubstring.substringAfter('|').twas())
append(currSubstring.substringAfter('|', "").twas())
}

currSubstring.startsWith("{{Nihongo", ignoreCase = true) -> {
Expand Down Expand Up @@ -1029,7 +1044,7 @@ fun String.toWikitextAnnotatedString(
}

currSubstring.startsWith("{{noflag", ignoreCase = true) -> {
val curr = currSubstring.substringAfter('|')
val curr = currSubstring.substringAfter('|', "")
append(curr.twas())
}

Expand Down Expand Up @@ -1380,6 +1395,9 @@ fun String.toWikitextAnnotatedString(
i++
}
}
} finally {
WikitextParserState.recursionDepth.set(currentDepth)
}
}

fun String.substringMatchingParen(
Expand Down