Use URL.resourceValues() for symlink detection (#428)

neonichu · pyrtsa · web-flow · commit c110bd16b296 · 2023-08-15T16:12:49.000-07:00
This should provide a significant performance improvement on macOS. See [this](#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
@@ -383,8 +383,10 @@ 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
`@@ -383,8 +383,10 @@ private struct LocalFileSystem: FileSystem {`
`383`	`383`	`}`
`384`	`384`
`385`	`385`	`func isSymlink(_ path: AbsolutePath) -> Bool {`
`386`		`- let attrs = try? FileManager.default.attributesOfItem(atPath: path.pathString)`
`387`		`- return attrs?[.type] as? FileAttributeType == .typeSymbolicLink`
	`386`	`+ let url = NSURL(fileURLWithPath: path.pathString)`
	`387`	+ // We are intentionally using `NSURL.resourceValues(forKeys:)` here since it improves performance on Darwin platforms.
	`388`	`+ let result = try? url.resourceValues(forKeys: [.isSymbolicLinkKey])`
	`389`	`+ return (result?[.isSymbolicLinkKey] as? Bool) == true`
`388`	`390`	`}`
`389`	`391`
`390`	`392`	`func isReadable(_ path: AbsolutePath) -> Bool {`