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Fix to avoid EXC_BAD_ACCESS when hooking functions #7

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Merged
merged 3 commits into from
Feb 15, 2024
Merged

Fix to avoid EXC_BAD_ACCESS when hooking functions #7

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90f3307
fix to avoid `EXC_BAD_ACCESS` when exchanging func implementation
p-x9 Feb 15, 2024
aa1c7a2
fix to avoid EXC_BAD_ACCESS when hooking functions
p-x9 Feb 15, 2024
6eaa383
refactor
p-x9 Feb 15, 2024
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37 changes: 21 additions & 16 deletions Sources/SwiftHook/SwiftHook+function.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -41,7 +41,6 @@ extension SwiftHook {
throw SwiftHookError.failedToExchangeFuncImplementation
}


public static func hookFunction(
_ target: String,
_ replacement: String,
Expand Down Expand Up @@ -130,6 +129,12 @@ extension SwiftHook {
return (firstSymbol, secondSymbol)
}

}

extension SwiftHook {
private static var replaced1: UnsafeMutableRawPointer?
private static var replaced2: UnsafeMutableRawPointer?

@discardableResult
private static func _exchangeFuncImplementation(
_ first: String,
Expand All @@ -144,37 +149,38 @@ extension SwiftHook {
print(firstSymbol, secondSymbol)
#endif

var replaced1 = UnsafeMutableRawPointer(bitPattern: -1)
var replaced2 = UnsafeMutableRawPointer(bitPattern: -1)

// hook first function
Self.replaced1 = nil
let f2s: Bool = rebindSymbol(
name: first,
replacement: secondSymbol,
replaced: &replaced1
replaced: &Self.replaced1
)

// hook second function
Self.replaced2 = nil
let s2f: Bool = rebindSymbol(
name: second,
replacement: firstSymbol,
replaced: &replaced2
replaced: &Self.replaced2
)

guard f2s && s2f else {
return false
}

guard let replaced1,
Int(bitPattern: replaced1) != -1 else {
guard Self.replaced1 != nil else {
throw SwiftHookError.failedToHookFirstFunction
}

guard let replaced2,
Int(bitPattern: replaced2) != -1 else {
guard Self.replaced2 != nil else {
throw SwiftHookError.failedToHookSecondFunction
}

return true
}
}

extension SwiftHook {
@discardableResult
private static func _hookFuncImplementation(
_ target: String,
Expand All @@ -193,23 +199,22 @@ extension SwiftHook {
print(stdlib_demangleName(replacement))
#endif

var replaced = UnsafeMutableRawPointer(bitPattern: -1)

Self.replaced1 = nil
let result: Bool = rebindSymbol(
name: target,
replacement: replacementSymbol,
replaced: &replaced
replaced: &Self.replaced1
)

guard result else { return false }

guard let replaced,
Int(bitPattern: replaced) != -1 else {
guard let replaced = Self.replaced1 else {
return false
}

if let original {
var originalReplaced = UnsafeMutableRawPointer(bitPattern: -1)
var originalReplaced: UnsafeMutableRawPointer?
let result: Bool = rebindSymbol(
name: original,
replacement: replaced,
Expand Down