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FileManager: Fix copyItem(atPath:toPath:) for directories and symlinks. #1515

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Merged
merged 1 commit into from
Apr 15, 2018
Merged

FileManager: Fix copyItem(atPath:toPath:) for directories and symlinks. #1515

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26 changes: 22 additions & 4 deletions Foundation/FileManager.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -442,16 +442,34 @@ open class FileManager : NSObject {
else {
return
}

func copyNonDirectory(srcPath: String, dstPath: String, fileType: FileAttributeType) throws {
if fileType == .typeSymbolicLink {
let destination = try destinationOfSymbolicLink(atPath: srcPath)
try createSymbolicLink(atPath: dstPath, withDestinationPath: destination)
} else if fileType == .typeRegular {
if createFile(atPath: dstPath, contents: contents(atPath: srcPath), attributes: nil) == false {
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This works, but a proper copy engine will read then write a limited portion of the source file at a time. For large files, this will result in an extreme high-water mark for memory usage.

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Good point, this was how the previous version was doing it but I will create a PR to fix it.

throw NSError(domain: NSCocoaErrorDomain, code: CocoaError.fileWriteUnknown.rawValue, userInfo: [NSFilePathErrorKey : NSString(string: dstPath)])
}
}
}

if fileType == .typeDirectory {
try createDirectory(atPath: dstPath, withIntermediateDirectories: false, attributes: nil)
let subpaths = try subpathsOfDirectory(atPath: srcPath)
for subpath in subpaths {
try copyItem(atPath: srcPath + "/" + subpath, toPath: dstPath + "/" + subpath)
let src = srcPath + "/" + subpath
let dst = dstPath + "/" + subpath
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I'm sorry, I don't recall—Do we not have an equivalent of -stringByAppendingPathComponent: in SCL?

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Only on NSString it appears, maybe a helper on String could be added in NSPathUtilities.

if let attrs = try? attributesOfItem(atPath: src), let fileType = attrs[.type] as? FileAttributeType {
if fileType == .typeDirectory {
try createDirectory(atPath: dst, withIntermediateDirectories: false, attributes: nil)
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This looks wrong. No recursion at all means we only go one extra level deep, no? (There should be a test for this.)

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The original implementation was wrong because it was recursing in every directory and then additional recursing in every sub directory. It now uses subpathsOfDirectory(atPath:) at the top level to get all of the subitems. There is are tests for it at https://github.com/apple/swift-corelibs-foundation/pull/1515/files/3c454b7358312d8d10dcb68a22d577e9ec816b58#diff-fffbc0319b30adac9f635327a750b82fR555

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Ah, I see. I misread this as contentsOfDirectory.

Please note that subpathsOfDirectory is very expensive, as it does all the directory enumeration at once and potentially creates a VERY large array. This is a high-water mark issue, similar to the contentsAtPath one. Using an enumerator would be much preferable here, and should be a fairly simple drop-in replacement.

} else {
try copyNonDirectory(srcPath: src, dstPath: dst, fileType: fileType)
}
}
}
} else {
if createFile(atPath: dstPath, contents: contents(atPath: srcPath), attributes: nil) == false {
throw NSError(domain: NSCocoaErrorDomain, code: CocoaError.fileWriteUnknown.rawValue, userInfo: [NSFilePathErrorKey : NSString(string: dstPath)])
}
try copyNonDirectory(srcPath: srcPath, dstPath: dstPath, fileType: fileType)
}
}

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33 changes: 29 additions & 4 deletions TestFoundation/TestFileManager.swift
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Expand Up @@ -516,7 +516,7 @@ class TestFileManager : XCTestCase {
let fm = FileManager.default
let srcPath = NSTemporaryDirectory() + "testdir\(NSUUID().uuidString)"
let destPath = NSTemporaryDirectory() + "testdir\(NSUUID().uuidString)"

func cleanup() {
ignoreError { try fm.removeItem(atPath: srcPath) }
ignoreError { try fm.removeItem(atPath: destPath) }
Expand Down Expand Up @@ -552,8 +552,13 @@ class TestFileManager : XCTestCase {
cleanup()
createDirectory(atPath: srcPath)
createDirectory(atPath: "\(srcPath)/tempdir")
createDirectory(atPath: "\(srcPath)/tempdir/subdir")
createDirectory(atPath: "\(srcPath)/tempdir/subdir/otherdir")
createDirectory(atPath: "\(srcPath)/tempdir/subdir/otherdir/extradir")
createFile(atPath: "\(srcPath)/tempdir/tempfile")
createFile(atPath: "\(srcPath)/tempdir/tempfile2")
createFile(atPath: "\(srcPath)/tempdir/subdir/otherdir/extradir/tempfile2")

do {
try fm.copyItem(atPath: srcPath, toPath: destPath)
} catch let error {
Expand All @@ -563,16 +568,36 @@ class TestFileManager : XCTestCase {
XCTAssertTrue(directoryExists(atPath: "\(destPath)/tempdir"))
XCTAssertTrue(fm.fileExists(atPath: "\(destPath)/tempdir/tempfile"))
XCTAssertTrue(fm.fileExists(atPath: "\(destPath)/tempdir/tempfile2"))

XCTAssertTrue(directoryExists(atPath: "\(destPath)/tempdir/subdir/otherdir/extradir"))
XCTAssertTrue(fm.fileExists(atPath: "\(destPath)/tempdir/subdir/otherdir/extradir/tempfile2"))

if (false == directoryExists(atPath: destPath)) {
return
}
do {
try fm.copyItem(atPath: srcPath, toPath: destPath)
XCTFail("Copy overwrites a file/folder that already exists")
} catch {
return
// ignore
}

// Test copying a symlink
let srcLink = srcPath + "/testlink"
let destLink = destPath + "/testlink"
do {
try fm.createSymbolicLink(atPath: srcLink, withDestinationPath: "linkdest")
try fm.copyItem(atPath: srcLink, toPath: destLink)
XCTAssertEqual(try fm.destinationOfSymbolicLink(atPath: destLink), "linkdest")
} catch {
XCTFail("\(error)")
}

do {
try fm.copyItem(atPath: srcLink, toPath: destLink)
XCTFail("Creating link where one already exists")
} catch {
// ignore
}
XCTFail("Copy overwrites a file/folder that already exists")
}

func test_homedirectoryForUser() {
Expand Down