text: /*
   * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   *
   * 1. Redistributions of source code must retain the above copyright notice, this
   *    list of conditions and the following disclaimer.
   *
   * 2. Redistributions in binary form must reproduce the above copyright notice,
   *    this list of conditions and the following disclaimer in the documentation
   *    and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
   * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
   * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
   * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   */
  
  #include <AK/StringView.h>
  #include <Kernel/FileSystem/FileDescription.h>
  #include <Kernel/FileSystem/VirtualFileSystem.h>
  #include <Kernel/Process.h>
  
  namespace Kernel {
  
  int Process::sys$readlink(Userspace<const Syscall::SC_readlink_params*> user_params)
  {
      REQUIRE_PROMISE(rpath);
  
      Syscall::SC_readlink_params params;
      if (!validate_read_and_copy_typed(&params, user_params))
          return -EFAULT;
  
      if (!validate(params.buffer))
          return -EFAULT;
  
      auto path = get_syscall_path_argument(params.path);
      if (path.is_error())
          return path.error();
  
      auto result = VFS::the().open(path.value(), O_RDONLY | O_NOFOLLOW_NOERROR, 0, current_directory());
      if (result.is_error())
          return result.error();
      auto description = result.value();
  
      if (!description->metadata().is_symlink())
          return -EINVAL;
  
      auto contents = description->read_entire_file();
      if (contents.is_error())
          return contents.error();
  
      auto& link_target = contents.value();
      auto size_to_copy = min(link_target.size(), params.buffer.size);
      copy_to_user(params.buffer.data, link_target.data(), size_to_copy);
      // Note: we return the whole size here, not the copied size.
      return link_target.size();
  }
  
  }
  