undelete - attempt to recover a deleted file
Standard C Library (libc, -lc)
undelete(const char *path);
The undelete() function attempts to recover the deleted file named by
path. Currently, this works only when the named object is a whiteout in
a union filesystem. The system call removes the whiteout causing any
objects in a lower layer of the union stack to become visible once more.
Eventually, the undelete functionality may be expanded to other filesystems
able to recover deleted files such as the log-structured filesystem.
Upon successful completion, a value of 0 is returned. Otherwise, a value
of -1 is returned and errno is set to indicate the error.
The undelete() succeeds unless:
[ENOTDIR] A component of the path prefix is not a directory.
[EINVAL] The pathname contains a character with the high-order bit
[ENAMETOOLONG] A component of a pathname exceeded 255 characters, or an
entire path name exceeded 1023 characters.
[EEXIST] The path does not reference a whiteout.
[ENOENT] The named whiteout does not exist.
[EACCES] Search permission is denied for a component of the path
prefix, or write permission is denied on the directory
containing the name to be undeleted.
[ELOOP] Too many symbolic links were encountered in translating
[EPERM] The directory containing the name is marked sticky, and
the containing directory is not owned by the effective
[EIO] An I/O error occurred while updating the directory entry.
[EROFS] The name resides on a read-only file system.
[EFAULT] path points outside the process's allocated address
An undelete function call first appeared in 4.4BSD -Lite.
BSD October 18, 1994 BSD
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