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UNDELETE(2) System Calls Manual UNDELETE(2)

undelete — attempt to recover a deleted file

library “libc”

#include <unistd.h>

int
undelete(const char *path);

The () system call attempts to recover the deleted file named by path. Currently, this works only when the named object is a whiteout in a union file system. The system call removes the whiteout causing any objects in a lower layer of the union stack to become visible once more.

Eventually, the () functionality may be expanded to other file systems able to recover deleted files such as the log-structured file system.

The undelete() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable errno is set to indicate the error.

The undelete() succeeds unless:

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A component of the path prefix is not a directory.
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A component of a pathname exceeded 255 characters, or an entire path name exceeded 1023 characters.
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The path does not reference a whiteout.
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The named whiteout does not exist.
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Search permission is denied for a component of the path prefix.
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Write permission is denied on the directory containing the name to be undeleted.
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Too many symbolic links were encountered in translating the pathname.
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The directory containing the name is marked sticky, and the containing directory is not owned by the effective user ID.
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The last component of the path is ‘..’.
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An I/O error occurred while updating the directory entry.
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The name resides on a read-only file system.
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The path argument points outside the process's allocated address space.

unlink(2), mount_unionfs(8)

The undelete() system call first appeared in 4.4BSD-Lite.

January 22, 2006 FreeBSD-12.0