std::experimental::filesystem::is_block_file
From cppreference.com
< cpp | experimental | fs
| Defined in header
<experimental/filesystem>
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| bool is_block_file( file_status s );
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(1) | (filesystem TS) |
| bool is_block_file( const path& p );
bool is_block_file( const path& p, error_code& ec ); |
(2) | (filesystem TS) |
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) Equivalent to is_block_file(status(p)) or is_block_file(status(p, ec)).
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[edit] Parameters
| s | - | file status to check |
| p | - | path to examine |
| ec | - | out-parameter for error reporting in the non-throwing overload |
[edit] 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.
[edit] Exceptions
1)
noexcept specification:
noexcept
2,3) 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
[edit] Notes
The information provided by this function is usually also provided as a byproduct of directory iteration. During directory iteration, calling is_block_file(*iterator) is less efficient than is_block_file(iterator->status())
[edit] 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
[edit] See also
| determines file attributes determines file attributes, checking the symlink target (function) |
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| represents file type and permissions (class) |
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| checks whether file status is known (function) |
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| checks whether the given path refers to a character device (function) |
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| checks whether the given path refers to a directory (function) |
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| checks whether the given path refers to a named pipe (function) |
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| checks whether the argument refers to an other file (function) |
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| checks whether the argument refers to a regular file (function) |
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| checks whether the argument refers to a named IPC socket (function) |
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| checks whether the argument refers to a symbolic link (function) |
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| checks whether path refers to existing file system object (function) |
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| 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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