std::experimental::filesystem::status, std::experimental::filesystem::symlink_status

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< cpp‎ | experimental‎ | fs
 
C++
 
Technical specifications
Filesystem library (filesystem TS)
Library fundamentals (library fundamentals TS)
Library fundamentals 2 (library fundamentals 2 TS)
Extensions for parallelism (parallelism TS)
Extensions for concurrency (concurrency TS)
Concepts (concepts TS)
Ranges (ranges TS)
Special mathematical functions (special math TR)
 
Filesystem library
Classes
Functions
File types
 
Defined in header <experimental/filesystem>
file_status status(const path& p);
file_status status(const path& p, error_code& ec) noexcept;
 (1) (filesystem TS)
file_status symlink_status(const path& p);
file_status symlink_status(const path& p, error_code& ec) noexcept;
 (2) (filesystem TS)
1) Determines the type and attributes of the filesystem object identified by p as if by POSIX stat (symlinks are followed to their targets).
  • If p is a regular file, returns file_status(file_type::regular).
  • If p is a directory, returns file_status(file_type::directory)
  • If p is a block special file, returns file_status(file_type::block)
  • If p is a character special file, returns file_status(file_type::character)
  • If p is a fifo or pipe file, returns file_status(file_type::fifo)
  • If p is a socket, returns file_status(file_type::socket)
  • 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)
2) Same as (1) except that the behavior is as if the POSIX lstat is used (symlinks are not followed):
  • If p is a symlink, returns file_status(file_type::symlink)

Parameters

p - path to examine
ec - out-parameter for error reporting in the non-throwing overload

Return value

The file status (a file_status object)

Exceptions

The overload that does not take a 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 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 information provided by this function is usually also provided as a byproduct of directory iteration, and may be obtained by the member functions of directory_entry. During directory iteration, calling status again is unnecessary.

Example

Run this code
#include <iostream>
#include <fstream>
#include <cstdio>
#include <cstring>
#include <experimental/filesystem>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/stat.h>
 
namespace fs = std::experimental::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

 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)
checks whether the given path refers to a named pipe
(function)
checks whether the argument refers to an other file
(function)
checks whether the argument refers to a regular file
(function)
checks whether the argument refers to a named IPC socket
(function)
checks whether the argument refers to a symbolic link
(function)
checks whether path refers to existing file system object
(function)
cached status of the file designated by this directory entry
cached symlink_status of the file designated by this directory entry
(public member function of std::experimental::filesystem::directory_entry)
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