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

std::filesystem::file_status status() const;
std::filesystem::file_status status( std::error_code& ec ) const;

(1)

(since C++17)

std::filesystem::file_status symlink_status() const;
std::filesystem::file_status symlink_status( std::error_code& ec ) const;

(2)

(since C++17)

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

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 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 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. This overload has

noexcept specification:

noexcept

Notes

The file status information is usually provided as a byproduct of directory iteration. Both boost.filesystem and the Technical Specification versions of the filesystem library cached the status and these member functions accessed the cached values without the cost of an additional system call, simplifying use of accessors such as is_directory during directory iteration. Status caching was removed during the merge to C++17 via LWG 2653.

Example

#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

file_status (C++17)	represents file type and permissions (class)
statussymlink_status (C++17)(C++17)	determines file attributes determines file attributes, checking the symlink target (function)
status_known (C++17)	checks whether file status is known (function)
is_block_file (C++17)	checks whether the given path refers to block device (function)
is_character_file (C++17)	checks whether the given path refers to a character device (function)
is_directory (C++17)	checks whether the given path refers to a directory (function)
is_fifo (C++17)	checks whether the given path refers to a named pipe (function)
is_other (C++17)	checks whether the argument refers to an other file (function)
is_regular_file (C++17)	checks whether the argument refers to a regular file (function)
is_socket (C++17)	checks whether the argument refers to a named IPC socket (function)
is_symlink (C++17)	checks whether the argument refers to a symbolic link (function)