std::filesystem::directory_entry::status, std::filesystem::directory_entry::symlink_status
From cppreference.com
< cpp | filesystem | directory entry
| std::filesystem::file_status status() const; |
(1) | (since C++17) |
| std::filesystem::file_status status( std::error_code& ec ) const noexcept; |
(2) | (since C++17) |
| std::filesystem::file_status symlink_status() const; |
(3) | (since C++17) |
| std::filesystem::file_status symlink_status( std::error_code& ec ) const noexcept; |
(4) | (since C++17) |
1,2) Returns status of the entry, as if determined by a filesystem::status call (symlinks are followed to their targets).
3,4) Returns status of the entry, as if determined by a filesystem::symlink_status call (symlinks are not followed).
Contents |
[edit] Parameters
| ec | - | out-parameter for error reporting in the non-throwing overload |
[edit] Return value
The status of the file referred to by the entry.
[edit] Exceptions
Any overload not marked noexcept may throw std::bad_alloc if memory allocation fails.
1,3) Throws std::filesystem::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.
2,4) 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.
[edit] Notes
Many low-level OS APIs for directory traversal retrieve file attributes along with the next directory entry. The constructors and the non-const member functions of std::filesystem::directory_iterator store these attributes, if any, in the pointed-to std::filesystem::directory_entry without calling directory_entry::refresh, which makes it possible to examine the attributes of the directory entries as they are being iterated over, without making additional system calls.
[edit] 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::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
[edit] See also
| updates the cached file attributes (public member function) | |
| checks whether directory entry refers to existing file system object (public member function) | |
| checks whether the directory entry refers to block device (public member function) | |
| checks whether the directory entry refers to a character device (public member function) | |
| checks whether the directory entry refers to a directory (public member function) | |
| checks whether the directory entry refers to a named pipe (public member function) | |
| checks whether the directory entry refers to an other file (public member function) | |
| checks whether the directory entry refers to a regular file (public member function) | |
| checks whether the directory entry refers to a named IPC socket (public member function) | |
| checks whether the directory entry refers to a symbolic link (public member function) | |
| returns the size of the file to which the directory entry refers (public member function) | |
| returns the number of hard links referring to the file to which the directory entry refers (public member function) | |
| gets the time of the last data modification of the file to which the directory entry refers (public member function) |
