CODEWITHSUNDEEP
swiftaddress-sanitizer
SquareBox
SquareBox

Reputation: 849

Debugging with Address Sanitizer

So I tried running our app with "Address Sanitizer" enabled. And I got this crash:

let sData = "-e5069fba-3612".data(using:String.Encoding.utf8)!
var pointer = sData.withUnsafeBytes {(bytes: UnsafePointer<CChar>) -> UnsafePointer<CChar> in
    return bytes
}
pointer = pointer.advanced(by: 1)
let tmpPIN = String(cString: pointer)
print(tmpPIN)

the crash points to let tmpPIN = String(cString: pointer). Does anyone know the reason behind this? I can't figure out why this is happening.

Note, the app runs fine when I disabled the "Address Sanitizer". Should I be worry about this or just ignore it?

Upvotes: 0

Views: 586

Answers (2)

Tom Harrington
Tom Harrington

Reputation: 70976

It seems you found an answer that works, but I'm adding one because I'm still kind of baffled by such complex code for such a simple problem.

Your code:

  • Transforms a Swift string to a Data object,
  • Gets unsafe bytes from that
  • Does pointer math on the unsafe bytes to move ahead one byte,
  • Finally converts the result back into a String.

Your fix makes it even more complex by appending an extra byte you don't even want (it works because C strings are expected to have a null character at the end, and your fix adds that).

This could be done far more simply as:

let sData = "-e5069fba-3612"
let tmpPIN = sData2.dropFirst()

The result is exactly the same.

Or you could handle multiple - characters at the start with something like 

let tmpPIN = sData.drop { $0 == "-" }

Which gives the same result for this string.

Upvotes: 2

SquareBox
SquareBox

Reputation: 849

I found this thread... When I add sData.append(0) after I initialize the sData the Address Sanitizer error is gone.

Upvotes: 0

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