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[5.6] FileLock encounters a runtime error when the path of the locked file is long (#277) #278

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Merged
merged 3 commits into from
Jan 15, 2022
Merged

[5.6] FileLock encounters a runtime error when the path of the locked file is long (#277) #278

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66ca488
FileLock encounters a runtime error when the path of the locked file …
abertelrud Jan 12, 2022
32d4af0
TSCBasic: repair the Windows build after #277
compnerd Jan 13, 2022
bea2cf8
Avoid using NAME_MAX in unit tests since it is not available on Windows.
abertelrud Jan 13, 2022
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29 changes: 25 additions & 4 deletions Sources/TSCBasic/Lock.swift
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
/*
This source file is part of the Swift.org open source project

Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
Copyright (c) 2014 - 2022 Apple Inc. and the Swift project authors
Licensed under Apache License v2.0 with Runtime Library Exception

See http://swift.org/LICENSE.txt for license information
Expand Down Expand Up @@ -178,12 +178,33 @@ public final class FileLock {
throw FileSystemError(.notDirectory, lockFilesDirectory)
}
// use the parent path to generate unique filename in temp
var lockFileName = (resolveSymlinks(fileToLock.parentDirectory).appending(component: fileToLock.basename)).components.joined(separator: "_")
var lockFileName = (resolveSymlinks(fileToLock.parentDirectory)
.appending(component: fileToLock.basename))
.components.joined(separator: "_")
.replacingOccurrences(of: ":", with: "_") + ".lock"
#if os(Windows)
// NTFS has an ARC limit of 255 codepoints
var lockFileUTF16 = lockFileName.utf16.suffix(255)
while String(lockFileUTF16) == nil {
lockFileUTF16 = lockFileUTF16.dropFirst()
}
lockFileName = String(lockFileUTF16) ?? lockFileName
#else
if lockFileName.hasPrefix(AbsolutePath.root.pathString) {
lockFileName = String(lockFileName.dropFirst(AbsolutePath.root.pathString.count))
}
let lockFilePath = lockFilesDirectory.appending(component: lockFileName + ".lock")

// back off until it occupies at most `NAME_MAX` UTF-8 bytes but without splitting scalars
// (we might split clusters but it's not worth the effort to keep them together as long as we get a valid file name)
var lockFileUTF8 = lockFileName.utf8.suffix(Int(NAME_MAX))
while String(lockFileUTF8) == nil {
// in practice this will only be a few iterations
lockFileUTF8 = lockFileUTF8.dropFirst()
}
// we will never end up with nil since we have ASCII characters at the end
lockFileName = String(lockFileUTF8) ?? lockFileName
#endif
let lockFilePath = lockFilesDirectory.appending(component: lockFileName)

let lock = FileLock(at: lockFilePath)
return try lock.withLock(type: type, body)
}
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8 changes: 7 additions & 1 deletion Tests/TSCBasicTests/FileSystemTests.swift
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Original file line number Diff line number Diff line change
@@ -1,7 +1,7 @@
/*
This source file is part of the Swift.org open source project

Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
Copyright (c) 2014 - 2022 Apple Inc. and the Swift project authors
Licensed under Apache License v2.0 with Runtime Library Exception

See http://swift.org/LICENSE.txt for license information
Expand Down Expand Up @@ -767,6 +767,12 @@ class FileSystemTests: XCTestCase {
let lockFile = tempDir.appending(component: "lockfile")

try _testFileSystemFileLock(fileSystem: localFileSystem, fileA: fileA, fileB: fileB, lockFile: lockFile)

// Test some long and edge case paths. We arrange to split between the C and the Cedilla by repeating 255 times.
let longEdgeCase1 = tempDir.appending(component: String(repeating: "Façade! ", count: 255).decomposedStringWithCanonicalMapping)
try localFileSystem.withLock(on: longEdgeCase1, type: .exclusive, {})
let longEdgeCase2 = tempDir.appending(component: String(repeating: "🏁", count: 255).decomposedStringWithCanonicalMapping)
try localFileSystem.withLock(on: longEdgeCase2, type: .exclusive, {})
}
}

Expand Down