std::filesystem::is_block_file

 

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External libraries

 

Filesystem library

Classes
filesystem::path filesystem::filesystem_error filesystem::directory_entry filesystem::directory_iterator filesystem::recursive_directory_iterator    filesystem::file_status filesystem::space_info	filesystem::file_type filesystem::file_time_type filesystem::perms filesystem::perm_options filesystem::copy_options filesystem::directory_options
Functions
filesystem::absolute filesystem::canonicalfilesystem::weakly_canonical filesystem::relativefilesystem::proximate filesystem::copy filesystem::copy_file filesystem::copy_symlink filesystem::create_directory filesystem::create_directories filesystem::create_hard_link filesystem::create_symlink filesystem::create_directory_symlink filesystem::current_path filesystem::temp_directory_path	filesystem::exists filesystem::equivalent filesystem::file_size filesystem::hard_link_count filesystem::last_write_time filesystem::permissions filesystem::read_symlink filesystem::remove filesystem::remove_all filesystem::rename filesystem::resize_file filesystem::space filesystem::status filesystem::symlink_status
File types
filesystem::is_block_file filesystem::is_character_file filesystem::is_directory filesystem::is_empty filesystem::status_known	filesystem::is_fifo filesystem::is_other filesystem::is_regular_file filesystem::is_socket filesystem::is_symlink

 

Defined in header <filesystem>
bool is_block_file(std::filesystem::file_status s )noexcept;	(1)	(since C++17)
bool is_block_file(conststd::filesystem::path& p );	(2)	(since C++17)
bool is_block_file(conststd::filesystem::path& p, std::error_code& ec )noexcept;	(3)	(since C++17)

Checks if the given file status or path corresponds to a block special file, as if determined by the POSIX S_ISBLK. Examples of block special files are block devices such as /dev/sda or /dev/loop0 on Linux.

1) Equivalent to s.type()== file_type::block.

2,3) Equivalent to is_block_file(status(p)) or is_block_file(status(p, ec)).

Parameters

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

Return value

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

Exceptions

Any overload not marked noexcept may throw std::bad_alloc if memory allocation fails.

2,3) 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.

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 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

See also

statussymlink_status (C++17)(C++17)	determines file attributes determines file attributes, checking the symlink target (function)
file_status (C++17)	represents file type and permissions (class)
status_known (C++17)	checks whether file status is known (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)
exists (C++17)	checks whether path refers to existing file system object (function)
is_block_file	checks whether the directory entry refers to block device (public member function of std::filesystem::directory_entry)