[SR-6338] Foundation Data.withUnsafeMutableBytes crash #4060
Description
| Previous ID | SR-6338 |
| Radar | rdar://problem/35442650 |
| Original Reporter | spc (JIRA User) |
| Type | Bug |
| Status | Closed |
| Resolution | Done |
Attachment: Download
Environment
-
Tested from Xcode Version 9.1 (9B55), iOS Playground.
-
Also tested on macOS High Sierra 10.13.1, with Apple Swift version 4.0.2 (swiftlang-900.0.69.2 clang-900.0.38),
Target: x86_64-apple-macosx10.9
Additional Detail from JIRA
| Votes | 0 |
| Component/s | Foundation |
| Labels | Bug, RunTimeCrash |
| Assignee | None |
| Priority | Medium |
md5: da28edbd18f5aa764fc8449dcf8f7cac
Issue Description:
Bellow swift code compiles, but failed to execute. The method 'withUnsafeMutableBytes' will raise an exception:
error: Execution was interrupted, reason: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0).
The process has been left at the point where it was interrupted, use "thread return -x" to return to the state before expression evaluation.
And in the call stack, I find the exception is raised from this method
// https://github.com/apple/swift/blob/swift-4.1-branch/stdlib/public/SDK/Foundation/Data.swift
public func withUnsafeMutableBytes<Result>(in range: Range<Int>, apply: (UnsafeMutableRawBufferPointer) throws -> Result) rethrows -> Result// The issue can be reproduced and always occurs.
import Foundation
extension Data {
mutating func overwrite<T>(_ value: T) {
let typeSize = MemoryLayout<T>.size
guard count == typeSize else {
print("Failed to write value into data")
return
}
self.withUnsafeMutableBytes({ (ptr: UnsafeMutablePointer<T>) -> Void in
ptr.pointee = value
return
})
return
}
}
var data = Data(count: 6)
let one: UInt16 = 1
data[0...1].overwrite(one)
data[2...3].overwrite(one)
data[4...5].overwrite(one)