Fix FileManager's extended attribute symlink handling

Sources/FoundationEssentials/FileManager/FileManager+Files.swift

@@ -522,21 +522,21 @@ extension _FileManagerImpl {
 
     private func _extendedAttributes(at path: UnsafePointer<CChar>, followSymlinks: Bool) throws -> [String : Data]? {
         #if canImport(Darwin)
-        var size = listxattr(path, nil, 0, 0)
+        var size = listxattr(path, nil, 0, followSymlinks ? 0 : XATTR_NOFOLLOW)
         #elseif os(FreeBSD)
         var size = (followSymlinks ? extattr_list_file : extattr_list_link)(path, EXTATTR_NAMESPACE_USER, nil, 0)
         #else
-        var size = listxattr(path, nil, 0)
+        var size = followSymlinks ? listxattr(path, nil, 0) : llistxattr(path, nil, 0)
         #endif
         guard size > 0 else { return nil }
         let keyList = UnsafeMutableBufferPointer<CChar>.allocate(capacity: size)
         defer { keyList.deallocate() }
         #if canImport(Darwin)
-        size = listxattr(path, keyList.baseAddress!, size, 0)
+        size = listxattr(path, keyList.baseAddress!, size, followSymlinks ? 0 : XATTR_NOFOLLOW)
         #elseif os(FreeBSD)
-        size = (followSymlinks ? extattr_list_file : extattr_list_link)(path, EXTATTR_NAMESPACE_USER, nil, 0)
+        size = (followSymlinks ? extattr_list_file : extattr_list_link)(path, EXTATTR_NAMESPACE_USER, keyList.baseAddress!, size)
         #else
-        size = listxattr(path, keyList.baseAddress!, size)
+        size = followSymlinks ? listxattr(path, keyList.baseAddress!, size) : llistxattr(path, keyList.baseAddress!, size)
         #endif
         guard size > 0 else { return nil }
 
@@ -553,7 +553,7 @@ extension _FileManagerImpl {
             }
             #endif
 
-            if let value = try _extendedAttribute(current, at: path, followSymlinks: false) {
+            if let value = try _extendedAttribute(current, at: path, followSymlinks: followSymlinks) {
                 extendedAttrs[currentKey] = value
             }
         }

Sources/FoundationEssentials/FileManager/FileManager+Utilities.swift

@@ -193,15 +193,15 @@ extension _FileManagerImpl {
             #else
             var result: Int32
             if followSymLinks {
-                result = lsetxattr(path, key, buffer.baseAddress!, buffer.count, 0)
-            } else {
                 result = setxattr(path, key, buffer.baseAddress!, buffer.count, 0)
+            } else {
+                result = lsetxattr(path, key, buffer.baseAddress!, buffer.count, 0)
             }
             #endif
 
             #if os(macOS) && FOUNDATION_FRAMEWORK
-            // if setxaddr failed and its a permission error for a sandbox app trying to set quaratine attribute, ignore it since its not
-            // permitted, the attribute will be put on the file by the quaratine MAC hook
+            // if setxattr failed and its a permission error for a sandbox app trying to set quarantine attribute, ignore it since its not
+            // permitted, the attribute will be put on the file by the quarantine MAC hook
             if result == -1 && errno == EPERM && _xpc_runtime_is_app_sandboxed() && strcmp(key, "com.apple.quarantine") == 0 {
                 return
             }

Tests/FoundationEssentialsTests/FileManager/FileManagerTests.swift

@@ -1046,6 +1046,74 @@ private struct FileManagerTests {
         }
     }
 
+    #if !os(Windows) && !os(WASI) && !os(OpenBSD) && !canImport(Android)
+    @Test func extendedAttributesDoNotFollowSymlinksWhenSetting() async throws {
+        let xattrKey = FileAttributeKey("NSFileExtendedAttributes")
+        #if canImport(Darwin)
+        let attrName = "com.swiftfoundation.symlinktest"
+        let probeName = "com.swiftfoundation.symlinkprobe"
+        #elseif os(Linux)
+        // Linux requires the user.* namespace prefix for regular files
+        let attrName = "user.swiftfoundation.symlinktest"
+        let probeName = "user.swiftfoundation.symlinkprobe"
+        #else
+        let attrName = "swiftfoundation.symlinktest"
+        let probeName = "swiftfoundation.symlinkprobe"
+        #endif
+        let attrValue = Data([0xAA, 0xBB, 0xCC])
+        let probeValue = Data([0x11, 0x22, 0x33])
+
+        try await FilePlayground {
+            File("target", contents: Data("payload".utf8))
+            SymbolicLink("link", destination: "target")
+        }.test { fileManager in
+            // First, prove that this environment supports xattrs on regular files and that we
+            // have permission to set them. If this fails, the symlink behavior isn't meaningful.
+            do {
+                try fileManager.setAttributes([xattrKey: [probeName: probeValue]], ofItemAtPath: "target")
+            } catch let error as CocoaError {
+                if error.code == .featureUnsupported { return }
+                guard let posix = error.underlying as? POSIXError else { throw error }
+                guard posix.code.rawValue == EOPNOTSUPP || posix.code.rawValue == ENOTSUP else { throw error }
+                return
+            }
+
+            // Attempt to set xattrs on the symlink.
+            var setSucceeded = false
+            do {
+                try fileManager.setAttributes(
+                    [xattrKey: [attrName: attrValue]], ofItemAtPath: "link")
+                setSucceeded = true
+            } catch let error as CocoaError {
+                if error.code == .featureUnsupported { return }
+                guard let posix = error.underlying as? POSIXError else { throw error }
+                guard posix.code.rawValue == EOPNOTSUPP || posix.code.rawValue == ENOTSUP || posix.code == .EPERM else { throw error }
+                // Fall through to verify target wasn't modified
+            }
+
+            let targetAttrs = try fileManager.attributesOfItem(atPath: "target")
+            let targetXattrs = targetAttrs[xattrKey] as? [String: Data]
+
+            // The target file must NOT have the xattr - this is the key assertion.
+            // If setAttributes incorrectly followed the symlink, the xattr would be on the target.
+            #expect(
+                targetXattrs?[attrName] == nil,
+                "setAttributes must not follow symlinks when setting extended attributes")
+
+            if setSucceeded {
+                // If setting on symlink succeeded, verify it's actually on the symlink
+                let linkAttrs = try fileManager.attributesOfItem(atPath: "link")
+                let linkXattrs = try #require(
+                    linkAttrs[xattrKey] as? [String: Data],
+                    "Expected extended attributes on symlink after setAttributes call")
+                #expect(
+                    linkXattrs[attrName] == attrValue,
+                    "xattr should be applied to the symlink itself")
+            }
+        }
+    }
+    #endif
+
     #if !canImport(Darwin) || os(macOS)
     @Test func currentUserHomeDirectory() async throws {
         let userName = ProcessInfo.processInfo.userName