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FileManager: Fix fileExists(atPath:isDirectory:) with dangling symlink #1514

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Merged
merged 1 commit into from
Apr 14, 2018
Merged

FileManager: Fix fileExists(atPath:isDirectory:) with dangling symlink #1514

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36 changes: 15 additions & 21 deletions Foundation/FileManager.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -593,32 +593,26 @@ open class FileManager : NSObject {

open func fileExists(atPath path: String, isDirectory: UnsafeMutablePointer<ObjCBool>?) -> Bool {
var s = stat()
if lstat(path, &s) >= 0 {
if let isDirectory = isDirectory {
if (s.st_mode & S_IFMT) == S_IFLNK {
if stat(path, &s) >= 0 {
isDirectory.pointee = ObjCBool((s.st_mode & S_IFMT) == S_IFDIR)
} else {
return false
}
} else {
let isDir = (s.st_mode & S_IFMT) == S_IFDIR
isDirectory.pointee = ObjCBool(isDir)
}
}
guard lstat(path, &s) >= 0 else {
return false
}

if (s.st_mode & S_IFMT) == S_IFLNK {
// don't chase the link for this magic case -- we might be /Net/foo
// which is a symlink to /private/Net/foo which is not yet mounted...
if (s.st_mode & S_IFMT) == S_IFLNK {
if (s.st_mode & S_ISVTX) == S_ISVTX {
return true
}
// chase the link; too bad if it is a slink to /Net/foo
stat(path, &s)
if isDirectory == nil && (s.st_mode & S_ISVTX) == S_ISVTX {
return true
}
// chase the link; too bad if it is a slink to /Net/foo
guard stat(path, &s) >= 0 else {
return false
}
} else {
return false
}

if let isDirectory = isDirectory {
isDirectory.pointee = ObjCBool((s.st_mode & S_IFMT) == S_IFDIR)
}

return true
}

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49 changes: 48 additions & 1 deletion TestFoundation/TestFileManager.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -23,6 +23,7 @@ class TestFileManager : XCTestCase {
("test_createFile", test_createFile ),
("test_moveFile", test_moveFile),
("test_fileSystemRepresentation", test_fileSystemRepresentation),
("test_fileExists", test_fileExists),
("test_fileAttributes", test_fileAttributes),
("test_fileSystemAttributes", test_fileSystemAttributes),
("test_setFileAttributes", test_setFileAttributes),
Expand Down Expand Up @@ -161,7 +162,53 @@ class TestFileManager : XCTestCase {
result.deallocate()
#endif
}


func test_fileExists() {
let fm = FileManager.default
let tmpDir = fm.temporaryDirectory.appendingPathComponent("testFileExistsDir")
let testFile = tmpDir.appendingPathComponent("testFile")
let goodSymLink = tmpDir.appendingPathComponent("goodSymLink")
let badSymLink = tmpDir.appendingPathComponent("badSymLink")
let dirSymLink = tmpDir.appendingPathComponent("dirSymlink")

ignoreError { try fm.removeItem(atPath: tmpDir.path) }

do {
try fm.createDirectory(atPath: tmpDir.path, withIntermediateDirectories: false, attributes: nil)
XCTAssertTrue(fm.createFile(atPath: testFile.path, contents: Data()))
try fm.createSymbolicLink(atPath: goodSymLink.path, withDestinationPath: testFile.path)
try fm.createSymbolicLink(atPath: badSymLink.path, withDestinationPath: "no_such_file")
try fm.createSymbolicLink(atPath: dirSymLink.path, withDestinationPath: "..")

var isDirFlag: ObjCBool = false
XCTAssertTrue(fm.fileExists(atPath: tmpDir.path))
XCTAssertTrue(fm.fileExists(atPath: tmpDir.path, isDirectory: &isDirFlag))
XCTAssertTrue(isDirFlag.boolValue)

isDirFlag = true
XCTAssertTrue(fm.fileExists(atPath: testFile.path))
XCTAssertTrue(fm.fileExists(atPath: testFile.path, isDirectory: &isDirFlag))
XCTAssertFalse(isDirFlag.boolValue)

isDirFlag = true
XCTAssertTrue(fm.fileExists(atPath: goodSymLink.path))
XCTAssertTrue(fm.fileExists(atPath: goodSymLink.path, isDirectory: &isDirFlag))
XCTAssertFalse(isDirFlag.boolValue)

isDirFlag = true
XCTAssertFalse(fm.fileExists(atPath: badSymLink.path))
XCTAssertFalse(fm.fileExists(atPath: badSymLink.path, isDirectory: &isDirFlag))

isDirFlag = false
XCTAssertTrue(fm.fileExists(atPath: dirSymLink.path))
XCTAssertTrue(fm.fileExists(atPath: dirSymLink.path, isDirectory: &isDirFlag))
XCTAssertTrue(isDirFlag.boolValue)
} catch {
XCTFail(String(describing: error))
}
ignoreError { try fm.removeItem(atPath: tmpDir.path) }
}

func test_fileAttributes() {
let fm = FileManager.default
let path = NSTemporaryDirectory() + "test_fileAttributes\(NSUUID().uuidString)"
Expand Down