Difference between revisions of "cpp/experimental/fs/rename"

Revision as of 14:09, 16 July 2016

Moves or renames the filesystem object identified by old_p to new_p as if by the POSIX rename:

• If old_p is a non-directory file, then new_p must be one of:

• the same file as old_p or a hardlink to it: nothing is done in this case
• existing non-directory file: new_p is first deleted, then, without allowing other processes to observe new_p as deleted, the pathname new_p is linked to the file and old_p is unlinked from the file. Write permissions are required to both the directory that contains old_p and the directory that contains new_p.
• non-existing file in an existing directory: The pathname new_p is linked to the file and old_p is unlinked from the file. Write permissions are required to both the directory that contains old_p and the directory that contains new_p.

• If old_p is a directory, then new_p must be one of:

• the same directory as old_p or a hardlink to it: nothing is done in this case
• existing directory: new_p is deleted if empty on POSIX systems, but this may be an error on other systems. If not an error, then new_p is first deleted, then, without allowing other processes to observe new_p as deleted, the pathname new_p is linked to the directory and old_p is unlinked from the directory. Write permissions are required to both the directory that contains old_p and the directory that contains new_p.
• non-existing directory, not ending with a directory separator, and whose parent directory exists: The pathname new_p is linked to the directory and old_p is unlinked from the directory. Write permissions are required to both the directory that contains old_p and the directory that contains new_p.

• Symlinks are not followed: if old_p is a symlink, it is itself renamed, not its target. If new_p is an existing symlink, it is itself erased, not its target.

Rename fails if

• new_p ends with dot or with dot-dot
• new_p names a non-existing directory ending with a directory separator
• old_p is a directory which is an ancestor of new_p

Parameters

Return value

(none)

Exceptions

Example

#include <iostream>
#include <fstream>
#include <experimental/filesystem>
namespace fs = std::experimental::filesystem;
int main()
{
    fs::path p = fs::current_path() / "sandbox";
    fs::create_directories(p/"from");
    std::ofstream(p/"from/file1.txt").put('a');
    fs::create_directory(p/"to");
 
//    fs::rename(p/"from/file1.txt", p/"to/"); // error: to is a directory
    fs::rename(p/"from/file1.txt", p/"to/file2.txt"); // OK
//    fs::rename(p/"from", p/"to"); // error: to is not empty
    fs::rename(p/"from", p/"to/subdir"); // OK
 
    fs::remove_all(p);
}

See also