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std::filesystem::is_socket(3)  C++ Standard Libary std::filesystem::is_socket(3)

NAME
     std::filesystem::is_socket - std::filesystem::is_socket

Synopsis
	Defined in header <filesystem>
	bool  is_socket(  std::filesystem::file_status s ) noexcept;	     (1)
     (since C++17)
	bool is_socket( const std::filesystem::path& p	);		     (2)
     (since C++17)
	bool  is_socket(  const std::filesystem::path& p, std::error_code&   (3)
     (since C++17)
	ec ) noexcept;

	Checks if the given file status or  path  corresponds  to  a  named  IPC
     socket, as if
	determined by the POSIX S_IFSOCK.

	1) Equivalent to s.type() == file_type::socket.
	2,3) Equivalent to is_socket(status(p)) or is_socket(status(p, ec)).

Parameters
	s  - file status to check
	p  - path to examine
	ec - out-parameter for error reporting in the non-throwing overload

Return value
	true  if  the file indicated by p or if the type indicated s refers to a
     named socket.
	The non-throwing overload returns false if an error occurs.

Exceptions
	Any overload not marked noexcept may throw std::bad_alloc if memory  al-
     location
	fails.

	2,3) Sets a std::error_code& parameter to the OS API error code if an OS
     API call
	fails, and executes ec.clear() if no errors occur.

Notes
	Named  sockets	are UNIX domain sockets constructed with socket and bind
     POSIX APIs,
	which may be used for advanced interprocess communication.  In	particu-
     lar, they may
	be  used  to transport open file descriptors from one running process to
     another.

Example
     // Run this code

      #include <cstdio>
      #include <cstring>
      #include <filesystem>
      #include <fstream>
      #include <iostream>
      #include <sys/socket.h>
      #include <sys/stat.h>
      #include <sys/un.h>
      #include <unistd.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");
	  fs::create_directory("sandbox/dir");
	  std::ofstream{"sandbox/file"}; // create regular file
	  fs::create_symlink("file", "sandbox/symlink");

	  mkfifo("sandbox/pipe", 0644);
	  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, reinterpret_cast<sockaddr*>(&addr), sizeof addr);

	  // demo different status accessors
	  for  (auto  it{fs::directory_iterator("sandbox")};  it  !=  fs::direc-
     tory_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 (prefer std::unique_ptr-based custom deleters)
	  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
	status		  determines file attributes
	symlink_status	   determines file attributes, checking the symlink tar-
     get
	(C++17) 	  (function)
	(C++17)
	file_status	  represents file type and permissions
	(C++17) 	  (class)
	status_known	  checks whether file status is known
	(C++17) 	  (function)
	is_block_file	  checks whether the given path refers to block device
	(C++17) 	  (function)
	is_character_file checks whether the given path refers	to  a  character
     device
	(C++17) 	  (function)
	is_directory	  checks whether the given path refers to a directory
	(C++17) 	  (function)
	is_fifo 	  checks whether the given path refers to a named pipe
	(C++17) 	  (function)
	is_other	  checks whether the argument refers to an other file
	(C++17) 	  (function)
	is_regular_file   checks whether the argument refers to a regular file
	(C++17) 	  (function)
	is_symlink	  checks whether the argument refers to a symbolic link
	(C++17) 	  (function)
	exists		  checks whether path refers to existing file system ob-
     ject
	(C++17) 	  (function)
			  checks  whether  the directory entry refers to a named
     IPC socket
	is_socket	  (public  member  function  of  std::filesystem::direc-
     tory_entry)

http://cppreference.com 	   2024.06.10	   std::filesystem::is_socket(3)
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