173 lines
4.3 KiB
Groff
173 lines
4.3 KiB
Groff
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.\" $NetBSD: getcwd.3,v 1.18 2010/04/29 06:54:26 jruoho Exp $
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.\"
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.\" Copyright (c) 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)getcwd.3 8.2 (Berkeley) 12/11/93
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.\"
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.Dd April 29, 2010
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.Dt GETCWD 3
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.Os
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.Sh NAME
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.Nm getcwd ,
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.Nm getwd
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.Nd get working directory pathname
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In unistd.h
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.Ft char *
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.Fn getcwd "char *buf" "size_t size"
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.Ft char *
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.Fn getwd "char *buf"
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.Sh DESCRIPTION
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The
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.Fn getcwd
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function copies the absolute pathname of the current working directory
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into the memory referenced by
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.Fa buf
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and returns a pointer to
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.Fa buf .
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The
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.Fa size
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argument is the size, in bytes, of the array referenced by
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.Fa buf .
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.Pp
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If
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.Fa buf
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is
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.Dv NULL ,
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space is allocated as necessary to store the pathname.
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This space may later be
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.Xr free 3 Ns 'd .
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.Pp
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The function
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.Fn getwd
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is a compatibility routine which calls
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.Fn getcwd
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with its
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.Fa buf
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argument and a size of
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.Dv MAXPATHLEN
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(as defined in the include
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file
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.In sys/param.h ) .
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Obviously,
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.Fa buf
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should be at least
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.Dv MAXPATHLEN
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bytes in length.
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.Pp
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These routines have traditionally been used by programs to save the
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name of a working directory for the purpose of returning to it.
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A much faster and less error-prone method of accomplishing this is to
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open the current directory
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.Pq Ql \&.
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and use the
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.Xr fchdir 2
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function to return.
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.Sh RETURN VALUES
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Upon successful completion, a pointer to the pathname is returned.
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Otherwise a
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.Dv NULL
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pointer is returned and the global variable
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.Va errno
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is set to indicate the error.
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In addition,
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.Fn getwd
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copies the error message associated with
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.Va errno
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into the memory referenced by
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.Fa buf .
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.Sh ERRORS
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The
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.Fn getcwd
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function
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will fail if:
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.Bl -tag -width Er
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.It Bq Er EACCES
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Read or search permission was denied for a component of the pathname.
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.It Bq Er EINVAL
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The
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.Fa size
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argument is zero.
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.It Bq Er ENOENT
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A component of the pathname no longer exists.
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.It Bq Er ENOMEM
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Insufficient memory is available.
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.It Bq Er ERANGE
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The
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.Fa size
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argument is greater than zero but smaller than the length of the pathname
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plus 1.
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.El
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.Sh SEE ALSO
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.Xr chdir 2 ,
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.Xr fchdir 2 ,
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.Xr malloc 3 ,
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.Xr strerror 3
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.Sh STANDARDS
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The
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.Fn getwd
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and
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.Fn getcwd
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functions conform to
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.St -p1003.1-90 .
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The
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.St -p1003.1-2004
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revision marked
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.Fn getwd
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as legacy and recommended the use of
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.Fn getcwd
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instead.
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The
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.St -p1003.1-2008
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revision removed
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.Fn getwd
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from the specification.
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.Pp
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The ability to specify a
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.Dv NULL
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pointer and have
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.Fn getcwd
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allocate memory as necessary is an extension.
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.Sh HISTORY
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The
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.Fn getwd
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function appeared in
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.Bx 4.0 .
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.Sh SECURITY CONSIDERATIONS
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As
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.Fn getwd
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does not know the length of the supplied buffer, it is possible
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for a long (but valid) path to overflow the buffer and provide
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a means for an attacker to exploit the caller.
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.Fn getcwd
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should be used in place of
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.Fn getwd
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(the latter is only provided for compatibility purposes).
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