std::experimental::filesystem::directory_entry::status,std::experimental::filesystem::directory_entry::symlink_status (3) - Linux Manuals

std::experimental::filesystem::directory_entry::status,std::experimental::filesystem::directory_entry::symlink_status: std::experimental::filesystem::directory_entry::status,std::experimental::filesystem::directory_entry::symlink_status

NAME

std::experimental::filesystem::directory_entry::status,std::experimental::filesystem::directory_entry::symlink_status - std::experimental::filesystem::directory_entry::status,std::experimental::filesystem::directory_entry::symlink_status

Synopsis

file_status status() const; (1) (filesystem TS)
file_status status( error_code& ec ) const;
file_status symlink_status() const; (2) (filesystem TS)
file_status symlink_status( error_code& ec ) const;

1) Returns the potentially cached status of the entry, as if determined by a status call (symlinks are followed to their targets)
2) Returns the potentially cached status of the entry, as if determined by a symlink_status call (symlinks are not followed)

Parameters

ec - out-parameter for error reporting in the non-throwing overload

Return value

The status of the file referred to by the entry.

Exceptions

The overload that does not take a error_code& parameter throws filesystem_error on underlying OS API errors, constructed with p as the first argument and the OS error code as the error code argument. std::bad_alloc may be thrown if memory allocation fails. The overload taking a error_code& parameter sets it to the OS API error code if an OS API call fails, and executes ec.clear() if no errors occur. This overload has
noexcept specification:
noexcept

Notes

The file status information is usually provided as a byproduct of directory iteration, in which case it is cached and may be obtained by these member functions without the cost of an additional system call. During directory iteration, calling status is unnecessary and accessors such as is_directory should be called with the cached status value, not with a path.

Example

// Run this code

  #include <iostream>
  #include <fstream>
  #include <cstdio>
  #include <cstring>
  #include <experimental/filesystem>
  #include <unistd.h>
  #include <sys/socket.h>
  #include <sys/un.h>
  #include <sys/stat.h>

  namespace fs = std::experimental::filesystem;

  void demo_status(const fs::path& p, fs::file_status s)
  {
      std::cout << p;
      // alternative: switch(s.type()) { case fs::file_type::regular: ...}
      if(fs::is_regular_file(s)) std::cout << " is a regular file\n";
      if(fs::is_directory(s)) std::cout << " is a directory\n";
      if(fs::is_block_file(s)) std::cout << " is a block device\n";
      if(fs::is_character_file(s)) std::cout << " is a character device\n";
      if(fs::is_fifo(s)) std::cout << " is a named IPC pipe\n";
      if(fs::is_socket(s)) std::cout << " is a named IPC socket\n";
      if(fs::is_symlink(s)) std::cout << " is a symlink\n";
      if(!fs::exists(s)) std::cout << " does not exist\n";
  }
  int main()
  {
      // create files of different kinds
      fs::create_directory("sandbox");
      std::ofstream("sandbox/file"); // create regular file
      fs::create_directory("sandbox/dir");
      mkfifo("sandbox/pipe", 0644);
      struct sockaddr_un addr;
      addr.sun_family = AF_UNIX;
      std::strcpy(addr.sun_path, "sandbox/sock");
      int fd = socket(PF_UNIX, SOCK_STREAM, 0);
      bind(fd, (struct sockaddr*)&addr, sizeof addr);
      fs::create_symlink("file", "sandbox/symlink");

      // demo different status accessors
      for(auto it = fs::directory_iterator("sandbox"); it != fs::directory_iterator(); ++it)
          demo_status(*it, it->symlink_status()); // use cached status from directory entry
      demo_status("dev/null", fs::status("/dev/null")); // direct calls to status
      demo_status("dev/sda", fs::status("/dev/sda"));
      demo_status("sandbox/no", fs::status("/sandbox/no"));

      // cleanup
      close(fd);
      fs::remove_all("sandbox");
  }

Possible output:

  "sandbox/file" is a regular file
  "sandbox/dir" is a directory
  "sandbox/pipe" is a named IPC pipe
  "sandbox/sock" is a named IPC socket
  "sandbox/symlink" is a symlink
  "dev/null" is a character device
  "dev/sda" is a block device
  "sandbox/no" does not exist