std::experimental::filesystem::perms

Defined in header `<experimental/filesystem>`
enum class perms;		(filesystem TS)

This type represents file access permissions. perms satisfies the requirements of BitmaskType (which means the bitwise operators operator&, operator|, operator^, operator~, operator&=, operator|=, and operator^= are defined for this type)

Access permissions model POSIX permission bits, and any individual file permissions (as reported by status) are a combination of some of the following bits:

Member constants

Member constant	Value (octal)	POSIX equivalent	Meaning
`none`	0		no permission bits are set
`owner_read`	0400	S_IRUSR	File owner has read permission
`owner_write`	0200	S_IWUSR	File owner has write permission
`owner_exec`	0100	S_IXUSR	File owner has execute/search permission
`owner_all`	0700	S_IRWXU	File owner has read, write, and execute/search permissions Equivalent to owner_read \| owner_write \| owner_exec
`group_read`	040	S_IRGRP	The file's user group has read permission
`group_write`	020	S_IWGRP	The file's user group has write permission
`group_exec`	010	S_IXGRP	The file's user group has execute/search permission
`group_all`	070	S_IRWXG	The file's user group has read, write, and execute/search permissions Equivalent to group_read \| group_write \| group_exec
`others_read`	04	S_IROTH	Other users have read permission
`others_write`	02	S_IWOTH	Other users have write permission
`others_exec`	01	S_IXOTH	Other users have execute/search permission
`others_all`	07	S_IRWXO	Other users have read, write, and execute/search permissions Equivalent to others_read \| others_write \| others_exec
`all`	0777		All users have read, write, and execute/search permissions Equivalent to owner_all \| group_all \| others_all
`set_uid`	04000	S_ISUID	Set user ID to file owner user ID on execution
`set_gid`	02000	S_ISGID	Set group ID to file's user group ID on execution
`sticky_bit`	01000	S_ISVTX	Implementation-defined meaning, but POSIX XSI specifies that when set on a directory, only file owners may delete files even if the directory is writeable to others (used with /tmp)
`mask`	07777		All valid permission bits. Equivalent to all \| set_uid \| set_gid \| sticky_bit

Additionally, the following constants of this type are defined, which do not represent permissions:

Member constant	Value (hex)	Meaning
`unknown`	0xFFFF	Unknown permissions (e.g. when file_status is created without permissions)
`add_perms`	0x10000	Control bit that instructs permissions to add, but not clear permission bits.
`remove_perms`	0x20000	Control bit that instructs permissions to clear, but not add permission bits
`resolve_symlinks`	0x40000	Control bit that instructs permissions to resolve symlinks

Notes

Permissions may not necessarily be implemented as bits, but they are treated that way conceptually.

Some permission bits may be ignored on some systems, and changing some bits may automatically change others (e.g. on platforms without owner/group/all distinction, setting any of the three write bits set all three)

Example

Run this code

#include <fstream>
#include <bitset>
#include <iostream>
#include <experimental/filesystem>
namespace fs = std::experimental::filesystem;
 
void demo_perms(fs::perms p)
{
     std::cout << ((p & fs::perms::owner_read) != fs::perms::none ? "r" : "-")
              << ((p & fs::perms::owner_write) != fs::perms::none ? "w" : "-")
              << ((p & fs::perms::owner_exec) != fs::perms::none ? "x" : "-")
              << ((p & fs::perms::group_read) != fs::perms::none ? "r" : "-")
              << ((p & fs::perms::group_write) != fs::perms::none ? "w" : "-")
              << ((p & fs::perms::group_exec) != fs::perms::none ? "x" : "-")
              << ((p & fs::perms::others_read) != fs::perms::none ? "r" : "-")
              << ((p & fs::perms::others_write) != fs::perms::none ? "w" : "-")
              << ((p & fs::perms::others_exec) != fs::perms::none ? "x" : "-")
              << '\n';
}
 
int main()
{
    std::ofstream("test.txt"); // create file
 
    std::cout << "Created file with permissions: ";
    demo_perms(fs::status("test.txt").permissions());
 
    fs::permissions("test.txt", fs::perms::add_perms |
                                fs::perms::owner_all | fs::perms::group_all);
 
    std::cout << "After adding o+rwx and g+rwx:  ";
    demo_perms(fs::status("test.txt").permissions());
 
    fs::remove("test.txt");
}

Possible output:

Created file with permissions: rw-r--r--
After adding o+rwx and g+rwx:  rwxrwxr--

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statussymlink_status	determines file attributes determines file attributes, checking the symlink target (function)
permissions	modifies file access permissions (function)

std::experimental::filesystem::perms

Member constants

Notes

Example

See also