mirror of
https://github.com/freebsd/freebsd-src
synced 2024-07-09 04:36:31 +00:00
8269e7673c
Remove core system call implementations and documentation to lib/libsys and lib/libsys/<arch> from lib/libc/sys and lib/libc/<arch>/<sys>. Update paths to allow libc to find them in their new home. Reviewed by: kib, emaste, imp Pull Request: https://github.com/freebsd/freebsd-src/pull/908
282 lines
7.2 KiB
Groff
282 lines
7.2 KiB
Groff
.\" Copyright (c) 1980, 1991, 1993
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 3. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.Dd February 23, 2021
|
|
.Dt UNLINK 2
|
|
.Os
|
|
.Sh NAME
|
|
.Nm unlink ,
|
|
.Nm unlinkat ,
|
|
.Nm funlinkat
|
|
.Nd remove directory entry
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.In unistd.h
|
|
.Ft int
|
|
.Fn unlink "const char *path"
|
|
.Ft int
|
|
.Fn unlinkat "int dfd" "const char *path" "int flag"
|
|
.Ft int
|
|
.Fn funlinkat "int dfd" "const char *path" "int fd" "int flag"
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Fn unlink
|
|
system call
|
|
removes the link named by
|
|
.Fa path
|
|
from its directory and decrements the link count of the
|
|
file which was referenced by the link.
|
|
If that decrement reduces the link count of the file
|
|
to zero,
|
|
and no process has the file open, then
|
|
all resources associated with the file are reclaimed.
|
|
If one or more process have the file open when the last link is removed,
|
|
the link is removed, but the removal of the file is delayed until
|
|
all references to it have been closed.
|
|
The
|
|
.Fa path
|
|
argument
|
|
may not be a directory.
|
|
.Pp
|
|
The
|
|
.Fn unlinkat
|
|
system call is equivalent to
|
|
.Fn unlink
|
|
or
|
|
.Fn rmdir
|
|
except in the case where
|
|
.Fa path
|
|
specifies a relative path.
|
|
In this case the directory entry to be removed is determined
|
|
relative to the directory associated with the file descriptor
|
|
.Fa dfd
|
|
instead of the current working directory.
|
|
.Pp
|
|
The values for
|
|
.Fa flag
|
|
are constructed by a bitwise-inclusive OR of flags from the following list,
|
|
defined in
|
|
.In fcntl.h :
|
|
.Bl -tag -width indent
|
|
.It Dv AT_REMOVEDIR
|
|
Remove the directory entry specified by
|
|
.Fa fd
|
|
and
|
|
.Fa path
|
|
as a directory, not a normal file.
|
|
.It Dv AT_RESOLVE_BENEATH
|
|
Only walk paths below the directory specified by the
|
|
.Ar fd
|
|
descriptor.
|
|
See the description of the
|
|
.Dv O_RESOLVE_BENEATH
|
|
flag in the
|
|
.Xr open 2
|
|
manual page.
|
|
.El
|
|
.Pp
|
|
If
|
|
.Fn unlinkat
|
|
is passed the special value
|
|
.Dv AT_FDCWD
|
|
in the
|
|
.Fa fd
|
|
parameter, the current working directory is used and the behavior is
|
|
identical to a call to
|
|
.Fa unlink
|
|
or
|
|
.Fa rmdir
|
|
respectively, depending on whether or not the
|
|
.Dv AT_REMOVEDIR
|
|
bit is set in flag.
|
|
.Pp
|
|
The
|
|
.Fn funlinkat
|
|
system call can be used to unlink an already-opened file, unless that
|
|
file has been replaced since it was opened.
|
|
It is equivalent to
|
|
.Fn unlinkat
|
|
in the case where
|
|
.Fa path
|
|
is already open as the file descriptor
|
|
.Fa fd .
|
|
Otherwise, the path will not be removed and an error will be returned.
|
|
The
|
|
.Fa fd
|
|
can be set the
|
|
.Dv FD_NONE .
|
|
In that case
|
|
.Fn funlinkat
|
|
behaves exactly like
|
|
.Fn unlinkat .
|
|
.Sh RETURN VALUES
|
|
.Rv -std unlink
|
|
.Sh ERRORS
|
|
The
|
|
.Fn unlink
|
|
succeeds unless:
|
|
.Bl -tag -width Er
|
|
.It Bq Er ENOTDIR
|
|
A component of the path prefix is not a directory.
|
|
.It Bq Er EISDIR
|
|
The named file is a directory.
|
|
.It Bq Er ENAMETOOLONG
|
|
A component of a pathname exceeded 255 characters,
|
|
or an entire path name exceeded 1023 characters.
|
|
.It Bq Er ENOENT
|
|
The named file does not exist.
|
|
.It Bq Er EACCES
|
|
Search permission is denied for a component of the path prefix.
|
|
.It Bq Er EACCES
|
|
Write permission is denied on the directory containing the link
|
|
to be removed.
|
|
.It Bq Er ELOOP
|
|
Too many symbolic links were encountered in translating the pathname.
|
|
.It Bq Er EPERM
|
|
The named file is a directory.
|
|
.It Bq Er EPERM
|
|
The named file has its immutable, undeletable or append-only flag set, see the
|
|
.Xr chflags 2
|
|
manual page for more information.
|
|
.It Bq Er EPERM
|
|
The parent directory of the named file has its immutable or append-only flag
|
|
set.
|
|
.It Bq Er EPERM
|
|
The directory containing the file is marked sticky,
|
|
and neither the containing directory nor the file to be removed
|
|
are owned by the effective user ID.
|
|
.It Bq Er EIO
|
|
An I/O error occurred while deleting the directory entry
|
|
or deallocating the inode.
|
|
.It Bq Er EINTEGRITY
|
|
Corrupted data was detected while reading from the file system.
|
|
.It Bq Er EROFS
|
|
The named file resides on a read-only file system.
|
|
.It Bq Er EFAULT
|
|
The
|
|
.Fa path
|
|
argument
|
|
points outside the process's allocated address space.
|
|
.It Bq Er ENOSPC
|
|
On file systems supporting copy-on-write or snapshots, there was not enough
|
|
free space to record metadata for the delete operation of the file.
|
|
.El
|
|
.Pp
|
|
In addition to the errors returned by the
|
|
.Fn unlink ,
|
|
the
|
|
.Fn unlinkat
|
|
may fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EBADF
|
|
The
|
|
.Fa path
|
|
argument does not specify an absolute path and the
|
|
.Fa fd
|
|
argument is neither
|
|
.Dv AT_FDCWD
|
|
nor a valid file descriptor open for searching.
|
|
.It Bq Er ENOTEMPTY
|
|
The
|
|
.Fa flag
|
|
parameter has the
|
|
.Dv AT_REMOVEDIR
|
|
bit set and the
|
|
.Fa path
|
|
argument names a directory that is not an empty directory,
|
|
or there are hard links to the directory other than dot or
|
|
a single entry in dot-dot.
|
|
.It Bq Er ENOTDIR
|
|
The
|
|
.Fa flag
|
|
parameter has the
|
|
.Dv AT_REMOVEDIR
|
|
bit set and
|
|
.Fa path
|
|
does not name a directory.
|
|
.It Bq Er EINVAL
|
|
The value of the
|
|
.Fa flag
|
|
argument is not valid.
|
|
.It Bq Er ENOTDIR
|
|
The
|
|
.Fa path
|
|
argument is not an absolute path and
|
|
.Fa fd
|
|
is neither
|
|
.Dv AT_FDCWD
|
|
nor a file descriptor associated with a directory.
|
|
.It Bq Er ENOTCAPABLE
|
|
.Fa path
|
|
is an absolute path,
|
|
or contained a ".." component leading to a
|
|
directory outside of the directory hierarchy specified by
|
|
.Fa fd ,
|
|
and the process is in capability mode or the
|
|
.Dv AT_RESOLVE_BENEATH
|
|
flag was specified.
|
|
.El
|
|
.Pp
|
|
In addition to the errors returned by
|
|
.Fn unlinkat ,
|
|
.Fn funlinkat
|
|
may fail if:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EDEADLK
|
|
The file descriptor is not associated with the path.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr chflags 2 ,
|
|
.Xr close 2 ,
|
|
.Xr link 2 ,
|
|
.Xr rmdir 2 ,
|
|
.Xr symlink 7
|
|
.Sh STANDARDS
|
|
The
|
|
.Fn unlinkat
|
|
system call follows The Open Group Extended API Set 2 specification.
|
|
.Sh HISTORY
|
|
The
|
|
.Fn unlink
|
|
function appeared in
|
|
.At v1 .
|
|
The
|
|
.Fn unlinkat
|
|
system call appeared in
|
|
.Fx 8.0 .
|
|
The
|
|
.Fn funlinkat
|
|
system call appeared in
|
|
.Fx 13.0 .
|
|
.Pp
|
|
The
|
|
.Fn unlink
|
|
system call traditionally allows the super-user to unlink directories which
|
|
can damage the file system integrity.
|
|
This implementation no longer permits it.
|