LibCore: Return a ByteString from System::mkdtemp

Paths are not necessarily UTF-8. While it doesn't matter much here, for
consistency with other parts of the system, let's use ByteStrings for
paths.

Userland/Libraries/LibCore/System.cpp

@@ -1159,14 +1159,14 @@ ErrorOr<int> mkstemp(Span<char> pattern)
     return fd;
 }
 
-ErrorOr<String> mkdtemp(Span<char> pattern)
+ErrorOr<ByteString> mkdtemp(Span<char> pattern)
 {
     auto* path = ::mkdtemp(pattern.data());
     if (path == nullptr) {
         return Error::from_errno(errno);
     }
 
-    return String::from_utf8(StringView { path, strlen(path) });
+    return ByteString { path, strlen(path) };
 }
 
 ErrorOr<void> rename(StringView old_path, StringView new_path)

Userland/Libraries/LibCore/System.h

@@ -185,7 +185,7 @@ ErrorOr<void> chdir(StringView path);
 ErrorOr<void> rmdir(StringView path);
 ErrorOr<pid_t> fork();
 ErrorOr<int> mkstemp(Span<char> pattern);
-ErrorOr<String> mkdtemp(Span<char> pattern);
+ErrorOr<ByteString> mkdtemp(Span<char> pattern);
 ErrorOr<void> fchmod(int fd, mode_t mode);
 ErrorOr<void> fchown(int fd, uid_t, gid_t);
 ErrorOr<void> rename(StringView old_path, StringView new_path);

Userland/Libraries/LibFileSystem/TempFile.cpp

@@ -28,7 +28,8 @@ ErrorOr<NonnullOwnPtr<TempFile>> TempFile::create_temp_directory()
     char pattern[] = "/tmp/tmp.XXXXXX";
 
     auto path = TRY(Core::System::mkdtemp(pattern));
-    return adopt_nonnull_own_or_enomem(new (nothrow) TempFile(Type::Directory, path));
+    auto string = TRY(String::from_byte_string(path));
+    return adopt_nonnull_own_or_enomem(new (nothrow) TempFile(Type::Directory, string));
 }
 
 ErrorOr<NonnullOwnPtr<TempFile>> TempFile::create_temp_file()

Userland/Utilities/runc/main.cpp

@@ -23,12 +23,12 @@ static ErrorOr<void> create_custom_vfs_root_context_layout(JsonArray const& layo
     char pattern[] = "/tmp/container_root_XXXXXX";
     auto temp_directory_path = TRY(Core::System::mkdtemp(pattern));
     TRY(LayoutParsing::create_root_mount_point(temp_directory_path, layout_creation_sequence));
-    auto vfs_root_context_layout = TRY(VFSRootContextLayout::create_with_root_mount_point(temp_directory_path.bytes_as_string_view()));
+    auto vfs_root_context_layout = TRY(VFSRootContextLayout::create_with_root_mount_point(temp_directory_path));
     TRY(LayoutParsing::handle_creation_sequence(*vfs_root_context_layout, layout_creation_sequence));
 
     TRY(vfs_root_context_layout->apply_mounts_on_vfs_root_context_id());
 
-    TRY(Core::System::umount({}, temp_directory_path.bytes_as_string_view()));
+    TRY(Core::System::umount({}, temp_directory_path));
 
     TRY(Core::System::rmdir(temp_directory_path));