Guard out extended or fs attributes related code on WASI (#784)

This commit guards out the extended attributes and file system
attributes related code on WASI as WASI does not support these
features. Just return nothing or ignore the set request.

(cherry picked from commit fab7195)

Author: kateinoigakukun

Sources/FoundationEssentials/FileManager/FileManager+Files.swift

@@ -484,7 +484,7 @@ extension _FileManagerImpl {
 #endif
     }
 
-#if !os(Windows)
+#if !os(Windows) && !os(WASI)
     private func _extendedAttribute(_ key: UnsafePointer<CChar>, at path: UnsafePointer<CChar>, followSymlinks: Bool) throws -> Data? {
         #if canImport(Darwin)
         var size = getxattr(path, key, nil, 0, 0, followSymlinks ? 0 : XATTR_NOFOLLOW)
@@ -638,10 +638,11 @@ extension _FileManagerImpl {
 
             var attributes = statAtPath.fileAttributes
             try? Self._catInfo(for: URL(filePath: path, directoryHint: .isDirectory), statInfo: statAtPath, into: &attributes)
-            
+            #if !os(WASI) // WASI does not support extended attributes
             if let extendedAttrs = try? _extendedAttributes(at: fsRep, followSymlinks: false) {
                 attributes[._extendedAttributes] = extendedAttrs
             }
+            #endif
 
             #if !targetEnvironment(simulator) && FOUNDATION_FRAMEWORK
             if statAtPath.isRegular || statAtPath.isDirectory {
@@ -703,6 +704,9 @@ extension _FileManagerImpl {
                 ]
             }
         }
+#elseif os(WASI)
+        // WASI does not support file system attributes
+        return [:]
 #else
         try fileManager.withFileSystemRepresentation(for: path) { rep in
             guard let rep else {
@@ -930,7 +934,12 @@ extension _FileManagerImpl {
             try Self._setCatInfoAttributes(attributes, path: path)
 
             if let extendedAttrs = attributes[.init("NSFileExtendedAttributes")] as? [String : Data] {
+                #if os(WASI)
+                // WASI does not support extended attributes
+                throw CocoaError.errorWithFilePath(.featureUnsupported, path)
+                #else
                 try Self._setAttributes(extendedAttrs, at: fileSystemRepresentation, followSymLinks: false)
+                #endif
             }
 
             if let date = attributes[.modificationDate] as? Date {

Sources/FoundationEssentials/FileManager/FileManager+Utilities.swift

@@ -173,7 +173,7 @@ extension _FileManagerImpl {
         #endif
     }
 
-#if !os(Windows)
+#if !os(Windows) && !os(WASI)
     static func _setAttribute(_ key: UnsafePointer<CChar>, value: Data, at path: UnsafePointer<CChar>, followSymLinks: Bool) throws {
         try value.withUnsafeBytes { buffer in
             #if canImport(Darwin)