Defined in header <filesystem> | ||
bool is_socket(std::filesystem::file_status s)noexcept; | (1) | (since C++17) |
bool is_socket(conststd::filesystem::path& p); | (2) | (since C++17) |
bool is_socket(conststd::filesystem::path& p,std::error_code& ec)noexcept; | (3) | (since C++17) |
Checks if the given file status or path corresponds to a named IPC socket, as if determined by the POSIXS_IFSOCK.
Contents |
| s | - | file status to check |
| p | - | path to examine |
| ec | - | out-parameter for error reporting in the non-throwing overload |
true if the file indicated byp or if the type indicateds refers to a named socket. The non-throwing overload returnsfalse if an error occurs.
Any overload not markednoexcept may throwstd::bad_alloc if memory allocation fails.
Named sockets are UNIX domain sockets constructed withsocket andbind POSIX APIs, which may be used for advanced interprocess communication. In particular, they may be used to transport open file descriptors from one running process to another.
#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 accessorsfor(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
(C++17)(C++17) | determines file attributes determines file attributes, checking the symlink target (function)[edit] |
(C++17) | represents file type and permissions (class)[edit] |
(C++17) | checks whether file status is known (function)[edit] |
(C++17) | checks whether the given path refers to block device (function)[edit] |
(C++17) | checks whether the given path refers to a character device (function)[edit] |
(C++17) | checks whether the given path refers to a directory (function)[edit] |
(C++17) | checks whether the given path refers to a named pipe (function)[edit] |
(C++17) | checks whether the argument refers to another file (function)[edit] |
(C++17) | checks whether the argument refers to a regular file (function)[edit] |
(C++17) | checks whether the argument refers to a symbolic link (function)[edit] |
(C++17) | checks whether path refers to existing file system object (function)[edit] |
| checks whether the directory entry refers to a named IPC socket (public member function of std::filesystem::directory_entry)[edit] |
