cp: changes to is_forbidden_to_copy_to_same_file function

Author: matrixhead

src/uu/cp/src/cp.rs

@@ -1524,11 +1524,40 @@ fn is_forbidden_to_copy_to_same_file(
 ) -> bool {
     // TODO To match the behavior of GNU cp, we also need to check
     // that the file is a regular file.
+    // only disable dereference if both source and dest is symlink and dereference flag is disabled
     let dereference_to_compare =
-        options.dereference(source_in_command_line) || !source.is_symlink();
-    paths_refer_to_same_file(source, dest, dereference_to_compare)
-        && !(options.force() && options.backup != BackupMode::NoBackup)
-        && !(dest.is_symlink() && options.backup != BackupMode::NoBackup)
+        options.dereference(source_in_command_line) || (!source.is_symlink() || !dest.is_symlink());
+    if !paths_refer_to_same_file(source, dest, dereference_to_compare) {
+        return false;
+    }
+    if options.backup != BackupMode::NoBackup {
+        if options.force() {
+            if !source.is_symlink() {
+                return false;
+            };
+        }
+        if source.is_symlink() && !options.dereference {
+            return false;
+        }
+        if dest.is_symlink() {
+            return false;
+        }
+    }
+    if options.copy_mode == CopyMode::Link {
+        if options.force() {
+            return false;
+        }
+        if source.is_symlink(){
+            return  false;
+        }
+    }
+    if options.copy_mode == CopyMode::SymLink {
+        if options.force() {
+            return false;
+        }
+    }
+
+    true
 }
 
 /// Back up, remove, or leave intact the destination file, depending on the options.