std::filesystem::directory_entry::status,std::filesystem::directory_entry::symlink_status (3) - Linux Man Pages

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

NAME

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

Synopsis


std::filesystem::file_status status() const; (1) (since C++17)
std::filesystem::file_status status( std::error_code& ec ) const noexcept;
std::filesystem::file_status symlink_status() const; (2) (since C++17)
std::filesystem::file_status symlink_status( std::error_code& ec ) const noexcept;


1) Returns status of the entry, as if determined by a status call (symlinks are followed to their targets)
2) Returns 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 std::error_code& parameter throws filesystem_error on underlying OS API errors, constructed with p as the first path argument and the OS error code as the error code argument. The overload taking a std::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. Any overload not marked noexcept may throw std::bad_alloc if memory allocation fails.

Notes


Many low-level OS APIs for directory traversal retrieve file attributes along with the next directory entry. The constructors and the non-const member functions of directory_iterator store these attributes, if any, in the pointed-to directory_entry without calling directory_entry::refresh, which makes it possible to examine the attributes of the directory entries as they are being iterated over, without making additional system calls.

Example


// Run this code


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


  namespace fs = std::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

See also


                  updates the cached file attributes
refresh (public member function)
                  checks whether directory entry refers to existing file system object
exists (public member function)
                  checks whether the directory entry refers to block device
is_block_file (public member function)
                  checks whether the directory entry refers to a character device
is_character_file (public member function)
                  checks whether the directory entry refers to a directory
is_directory (public member function)
                  checks whether the directory entry refers to a named pipe
is_fifo (public member function)
                  checks whether the directory entry refers to an other file
is_other (public member function)
                  checks whether the directory entry refers to a regular file
is_regular_file (public member function)
                  checks whether the directory entry refers to a named IPC socket
is_socket (public member function)
                  checks whether the directory entry refers to a symbolic link
is_symlink (public member function)
                  returns the size of the file to which the directory entry refers
file_size (public member function)
                  returns the number of hard links referring to the file to which the directory entry refers
hard_link_count (public member function)
                  gets or sets the time of the last data modification of the file to which the directory entry refers
last_write_time (public member function)