From bb0feebddc7d60afefc62a6e245a532cf5252296 Mon Sep 17 00:00:00 2001
From: Tim Schumacher <timschumi@gmx.de>
Date: Tue, 12 Jul 2022 23:57:14 +0200
Subject: [PATCH] cp: Implement the granular `--preserve` flag

---
 Userland/Utilities/cp.cpp | 43 +++++++++++++++++++++++++++++++--------
 1 file changed, 34 insertions(+), 9 deletions(-)

diff --git a/Userland/Utilities/cp.cpp b/Userland/Utilities/cp.cpp
index ce7fef9c75..781b33b18d 100644
--- a/Userland/Utilities/cp.cpp
+++ b/Userland/Utilities/cp.cpp
@@ -17,7 +17,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     TRY(Core::System::pledge("stdio rpath wpath cpath fattr chown"));
 
     bool link = false;
-    bool preserve = false;
+    auto preserve = Core::File::PreserveMode::Nothing;
     bool recursion_allowed = false;
     bool verbose = false;
     Vector<StringView> sources;
@@ -25,7 +25,37 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     Core::ArgsParser args_parser;
     args_parser.add_option(link, "Link files instead of copying", "link", 'l');
-    args_parser.add_option(preserve, "Preserve time, UID/GID and file permissions", nullptr, 'p');
+    args_parser.add_option({
+        Core::ArgsParser::OptionArgumentMode::Optional,
+        "Preserve a selection of mode, ownership and timestamps. Defaults to all three if the option is present but no list is given.",
+        "preserve",
+        'p',
+        "attributes",
+        [&preserve](char const* s) {
+            if (!s) {
+                preserve = Core::File::PreserveMode::Permissions | Core::File::PreserveMode::Ownership | Core::File::PreserveMode::Timestamps;
+                return true;
+            }
+
+            bool values_ok = true;
+
+            StringView { s, strlen(s) }.for_each_split_view(',', false, [&](StringView value) {
+                if (value == "mode"sv) {
+                    preserve |= Core::File::PreserveMode::Permissions;
+                } else if (value == "ownership"sv) {
+                    preserve |= Core::File::PreserveMode::Ownership;
+                } else if (value == "timestamps"sv) {
+                    preserve |= Core::File::PreserveMode::Timestamps;
+                } else {
+                    warnln("cp: Unknown or unimplemented --preserve attribute: '{}'", value);
+                    values_ok = false;
+                }
+            });
+
+            return values_ok;
+        },
+        Core::ArgsParser::OptionHideMode::None,
+    });
     args_parser.add_option(recursion_allowed, "Copy directories recursively", "recursive", 'R');
     args_parser.add_option(recursion_allowed, "Same as -R", nullptr, 'r');
     args_parser.add_option(verbose, "Verbose", "verbose", 'v');
@@ -33,7 +63,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     args_parser.add_positional_argument(destination, "Destination file path", "destination");
     args_parser.parse(arguments);
 
-    if (preserve) {
+    if (has_flag(preserve, Core::File::PreserveMode::Permissions)) {
         umask(0);
     } else {
         TRY(Core::System::pledge("stdio rpath wpath cpath fattr"));
@@ -41,11 +71,6 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
 
     bool destination_is_existing_dir = Core::File::is_directory(destination);
 
-    auto preserve_mode = Core::File::PreserveMode::Nothing;
-
-    if (preserve)
-        preserve_mode = Core::File::PreserveMode::Permissions | Core::File::PreserveMode::Ownership | Core::File::PreserveMode::Timestamps;
-
     for (auto& source : sources) {
         auto destination_path = destination_is_existing_dir
             ? String::formatted("{}/{}", destination, LexicalPath::basename(source))
@@ -56,7 +81,7 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
             recursion_allowed ? Core::File::RecursionMode::Allowed : Core::File::RecursionMode::Disallowed,
             link ? Core::File::LinkMode::Allowed : Core::File::LinkMode::Disallowed,
             Core::File::AddDuplicateFileMarker::No,
-            preserve_mode);
+            preserve);
 
         if (result.is_error()) {
             if (result.error().tried_recursing)