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Showing content from https://en.cppreference.com/w/cpp/language/../error/error_code/../../filesystem/status.html below:

std::filesystem::status, std::filesystem::symlink_status - cppreference.com

Determines the type and attributes of the filesystem object identified by

as if by POSIX

(symlinks are followed to their targets). In the following description,

is the result of

, where

is obtained as if by taking

from the POSIX

and converting it to the type

.

• If p is a regular file (as if by POSIX S_ISREG), returns file_status(file_type::regular, prms).
• If p is a directory (as if by POSIX S_ISDIR), returns file_status(file_type::directory, prms).
• If p is a block special file (as if by POSIX S_ISBLK), returns file_status(file_type::block, prms).
• If p is a character special file (as if by POSIX S_ISCHR), returns file_status(file_type::character, prms).
• If p is a fifo or pipe file (as if by POSIX S_ISFIFO), returns file_status(file_type::fifo, prms).
• If p is a socket (as if by POSIX S_ISSOCK), returns file_status(file_type::socket, prms).
• If p has an implementation-defined file type, returns file_status(file_type::A, prms) where A is the implementation-defined file_type constant for that type.
• If p does not exist, returns file_status(file_type::not_found).
• If p exists but file attributes cannot be determined, e.g. due to lack of permissions, returns file_status(file_type::unknown).
• If errors prevent even knowing whether p exists, the non-throwing overload sets ec and returns file_status(file_type::none), and the throwing overload throws filesystem_error.
• Otherwise, returns file_status(file_type::unknown, prms).

Same as

except that the behavior is as if the POSIX

is used (symlinks are not followed):

• If p is a symlink, returns file_status(file_type::symlink).

The file status (a filesystem::file_status object).

Any overload not marked noexcept may throw std::bad_alloc if memory allocation fails.

Throws

on underlying OS API errors, constructed with

as the first path argument and the OS error code as the error code argument.

Sets a

parameter to the OS API error code if an OS API call fails, and executes

if no errors occur.

The information provided by this function is usually also provided as a byproduct of directory iteration, and may be obtained by the member functions of filesystem::directory_entry. During directory iteration, calling status again is unnecessary.

#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::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 (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

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