std::filesystem::is_fifo

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

Checks if the given file status or path corresponds to a FIFO or pipe file as if determined by POSIX S_ISFIFO.

1) Equivalent to s.type() == file_type::fifo.
2) Equivalent to is_fifo(status(p)) or is_fifo(status(p, ec)) respectively

Parameters

s - file status to check
p - path to query
ec - error code to modify in case of errors

Return value

true if the file indicated by p or if the type indicated s refers to a FIFO pipe, false otherwise. The non-throwing overload returns false if an error occurs.

Exceptions

2) 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.

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

See also

(C++17)(C++17)
determines file attributes
determines file attributes, checking the symlink target
(function)
represents file type and permissions
(class)
checks whether file status is known
(function)
checks whether the given path refers to block device
(function)
checks whether the given path refers to a character device
(function)
checks whether the given path refers to a directory
(function)
(C++17)
checks whether the argument refers to an other file
(function)
checks whether the argument refers to a regular file
(function)
(C++17)
checks whether the argument refers to a named IPC socket
(function)
checks whether the argument refers to a symbolic link
(function)
(C++17)
checks whether path refers to existing file system object
(function)
checks whether the directory entry refers to a named pipe
(public member function of std::filesystem::directory_entry)