Use URL.resourceValues() for symlink detection

neonichu · pyrtsa · neonichu · commit 06d5f76e68f2 · 2023-08-15T12:45:08.000-07:00
This should provide a significant performance improvement on macOS. See [this](swiftlang#400 (comment)]) for more discussion on non-macOS platforms. Co-authored-by: Pyry Jahkola <pyry.jahkola@iki.fi>
diff --git a/Sources/TSCBasic/FileSystem.swift b/Sources/TSCBasic/FileSystem.swift
@@ -370,8 +370,10 @@ private struct LocalFileSystem: FileSystem {
     }
 
     func isSymlink(_ path: AbsolutePath) -> Bool {
-        let attrs = try? FileManager.default.attributesOfItem(atPath: path.pathString)
-        return attrs?[.type] as? FileAttributeType == .typeSymbolicLink
+        let url = NSURL(fileURLWithPath: path.pathString)
+        // We are intentionally using `NSURL.resourceValues(forKeys:)` here since it improves performance on Darwin platforms.
+        let result = try? url.resourceValues(forKeys: [.isSymbolicLinkKey])
+        return (result?[.isSymbolicLinkKey] as? Bool) == true
     }
 
     func isReadable(_ path: AbsolutePath) -> Bool {

Original file line number	Diff line number	Diff line change
`@@ -370,8 +370,10 @@ private struct LocalFileSystem: FileSystem {`
`370`	`370`	`}`
`371`	`371`
`372`	`372`	`func isSymlink(_ path: AbsolutePath) -> Bool {`
`373`		`- let attrs = try? FileManager.default.attributesOfItem(atPath: path.pathString)`
`374`		`- return attrs?[.type] as? FileAttributeType == .typeSymbolicLink`
	`373`	`+ let url = NSURL(fileURLWithPath: path.pathString)`
	`374`	+ // We are intentionally using `NSURL.resourceValues(forKeys:)` here since it improves performance on Darwin platforms.
	`375`	`+ let result = try? url.resourceValues(forKeys: [.isSymbolicLinkKey])`
	`376`	`+ return (result?[.isSymbolicLinkKey] as? Bool) == true`
`375`	`377`	`}`
`376`	`378`
`377`	`379`	`func isReadable(_ path: AbsolutePath) -> Bool {`