rename(2) man page

RENAME(2) System Calls Manual RENAME(2)

NAME
rename, renameat, renamex_np, renameatx_np – change the name of a file

SYNOPSIS
#include <stdio.h>

int
rename(const char *old, const char *new);

int
renameat(int fromfd, const char *from, int tofd, const char *to);

int
renamex_np(const char *from, const char *to, unsigned int flags);

int
renameatx_np(int fromfd, const char *from, int tofd, const char *to,
unsigned int flags);

DESCRIPTION
The rename() system call causes the link named old to be renamed as new.
If new exists, it is first removed. Both old and new must be of the same
type (that is, both must be either directories or non-directories) and
must reside on the same file system.

The rename() system call guarantees that an instance of new will always
exist, even if the system should crash in the middle of the operation.

If the final component of old is a symbolic link, the symbolic link is
renamed, not the file or directory to which it points.

The renameat() system call is equivalent to rename() except in the case
where either from or to specifies a relative path. If from is a relative
path, the file to be renamed is located relative to the directory
associated with the file descriptor fromfd instead of the current working
directory. If the to is a relative path, the same happens only relative
to the directory associated with tofd. If the renameat() is passed the
special value AT_FDCWD in the fromfd or tofd parameter, the current
working directory is used in the determination of the file for the
respective path parameter.

The renamex_np() and renameatx_np() system calls are similar to their
counterparts except that they take a flags argument. Values for flags
are constructed with below bits set:

RENAME_SWAP
On file systems that support it (see getattrlist(2)
VOL_CAP_INT_RENAME_SWAP), it will cause the source and
target to be atomically swapped. Source and target need
not be of the same type, i.e. it is possible to swap a file
with a directory. EINVAL is returned in case of bitwise-
inclusive OR with RENAME_EXCL.

RENAME_EXCL
On file systems that support it (see getattrlist(2)
VOL_CAP_INT_RENAME_EXCL), it will cause EEXIST to be
returned if the destination already exists. EINVAL is
returned in case of bitwise-inclusive OR with RENAME_SWAP.

RENAME_NOFOLLOW_ANY
If any symbolic links are encountered during pathname
resolution, an error is returned.

CAVEATS
The system can deadlock if a loop is present in the file system graph.
This loop takes the form of an entry in directory ‘a’, say ‘a/foo’, being
a hard link to directory ‘b’, and an entry in directory ‘b’, say ‘b/bar’,
being a hard link to directory ‘a’. When such a loop exists and two
separate processes attempt to perform ‘rename a/foo b/bar’ and ‘rename
b/bar a/foo’, respectively, the system may deadlock attempting to lock
both directories for modification.

Whether or not hard links to directories are supported is specific to the
underlying filesystem implementation.

It is recommended that any hard links to directories in an underlying
filesystem should be replaced by symbolic links by the system
administrator to avoid the possibility of deadlocks.

Moving or renaming a file or directory into a directory with inheritable
ACLs does not result in ACLs being set on the file or directory. Use
acl(3) in conjunction with rename() to set ACLs on the file or directory.

RETURN VALUES
A 0 value is returned if the operation succeeds, otherwise rename()
returns -1 and the global variable errno indicates the reason for the
failure.

ERRORS
The rename() system call will fail and neither of the argument files will
be affected if:

[EACCES] A component of either path prefix denies search
permission.

[EACCES] The requested operation requires writing in a
directory (e.g., new, new/.., or old/..) whose modes
disallow this.

[EACCES] old is a directory and it, or some descendent in the
namespace, is open and the file system format does
does not support renaming a directory with open
descendents (see getattrlist(2)
VOL_CAP_INT_RENAME_OPENFAIL).

[EDQUOT] The directory in which the entry for the new name is
being placed cannot be extended because the user's
quota of disk blocks on the file system containing the
directory has been exhausted.

[EEXIST] flags has RENAME_EXCL set but new already exists.

[EFAULT] Path points outside the process's allocated address
space.

[EINVAL] Old is a parent directory of new, or an attempt is
made to rename ‘.’ or ‘..’. If RENAME_SWAP is used,
then EINVAL will also be returned if new is a parent
directory of old. If both RENAME_SWAP and RENAME_EXCL
bits are set in flags, then EINVAL will be returned.

[EINVAL] flags has an invalid value.

[EIO] An I/O error occurs while making or updating a
directory entry.

[EISDIR] new is a directory, but old is not a directory.

[ELOOP] Too many symbolic links are encountered in translating
either pathname. This is taken to be indicative of a
looping symbolic link.

[ELOOP] If RENAME_NOFOLLOW_ANY was passed and a symbolic link
was encountered in translating either pathname.

[ENAMETOOLONG] A component of a pathname exceeds {NAME_MAX}
characters, or an entire path name exceeds {PATH_MAX}
characters.

[ENOENT] A component of the old path does not exist, or a path
prefix of new does not exist.

[ENOENT] flags has RENAME_SWAP set but new does not exist.

[ENOSPC] The directory in which the entry for the new name is
being placed cannot be extended because there is no
space left on the file system containing the
directory.

[ENOTDIR] A component of either path prefix is not a directory.

[ENOTDIR] old is a directory, but new is not a directory.

[ENOTEMPTY] New is a directory and is not empty.

[ENOTSUP] flags has a value that is not supported by the file
system.

[EPERM] The directory containing old is marked sticky, and
neither the containing directory nor old are owned by
the effective user ID.

[EPERM] The new file exists, the directory containing new is
marked sticky, and neither the containing directory
nor new are owned by the effective user ID.

[EROFS] The requested link requires writing in a directory on
a read-only file system.

[EXDEV] The link named by new and the file named by old are on
different logical devices (file systems). Note that
this error code will not be returned if the
implementation permits cross-device links.

[EDEADLK] A component of either pathname refers to a “dataless”
directory that requires materialization and the I/O
policy of the current thread or process disallows
dataless directory materialization (see
getiopolicy_np(3)).

[EDEADLK] The from pathname refers to a “dataless” file or
directory that must be materialized before being moved
to its new location and the I/O policy of the current
thread or process disallows file or directory
materialization (see getiopolicy_np(3)).

The renameat() and renameatx_np() calls may also fail with:

[EBADF] The from argument does not specify an absolute path
and the fromfd argument is neither AT_FDCWD nor a
valid file descriptor open for searching, or the to
argument does not specify an absolute path and the
tofd argument is neither AT_FDCWD nor a valid file
descriptor open for searching.

[ENOTDIR] The from argument is not an absolute path and fromfd
is neither AT_FDCWD nor a file descriptor associated
with a directory, or the to argument is not an
absolute path and tofd is neither AT_FDCWD nor a file
descriptor associated with a directory.

CONFORMANCE
The restriction on renaming a directory whose permissions disallow
writing is based on the fact that UFS directories contain a ".." entry.
If renaming a directory would move it to another parent directory, this
entry needs to be changed.

This restriction has been generalized to disallow renaming of any write-
disabled directory, even when this would not require a change to the ".."
entry. For consistency, HFS+ directories emulate this behavior.