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Revision 1.18, Thu Apr 29 06:54:26 2010 UTC (6 years ago) by jruoho
Add some STANDARDS lingo, mainly to note the functions that have been removed from POSIX (2008).
.\" $NetBSD: getcwd.3,v 1.18 2010/04/29 06:54:26 jruoho Exp $ .\" .\" Copyright (c) 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. .\" .\" @(#)getcwd.3 8.2 (Berkeley) 12/11/93 .\" .Dd April 29, 2010 .Dt GETCWD 3 .Os .Sh NAME .Nm getcwd , .Nm getwd .Nd get working directory pathname .Sh LIBRARY .Lb libc .Sh SYNOPSIS .In unistd.h .Ft char * .Fn getcwd "char *buf" "size_t size" .Ft char * .Fn getwd "char *buf" .Sh DESCRIPTION The .Fn getcwd function copies the absolute pathname of the current working directory into the memory referenced by .Fa buf and returns a pointer to .Fa buf . The .Fa size argument is the size, in bytes, of the array referenced by .Fa buf . .Pp If .Fa buf is .Dv NULL , space is allocated as necessary to store the pathname. This space may later be .Xr free 3 Ns 'd . .Pp The function .Fn getwd is a compatibility routine which calls .Fn getcwd with its .Fa buf argument and a size of .Dv MAXPATHLEN (as defined in the include file .In sys/param.h ) . Obviously, .Fa buf should be at least .Dv MAXPATHLEN bytes in length. .Pp These routines have traditionally been used by programs to save the name of a working directory for the purpose of returning to it. A much faster and less error-prone method of accomplishing this is to open the current directory .Pq Ql \&. and use the .Xr fchdir 2 function to return. .Sh RETURN VALUES Upon successful completion, a pointer to the pathname is returned. Otherwise a .Dv NULL pointer is returned and the global variable .Va errno is set to indicate the error. In addition, .Fn getwd copies the error message associated with .Va errno into the memory referenced by .Fa buf . .Sh ERRORS The .Fn getcwd function will fail if: .Bl -tag -width Er .It Bq Er EACCES Read or search permission was denied for a component of the pathname. .It Bq Er EINVAL The .Fa size argument is zero. .It Bq Er ENOENT A component of the pathname no longer exists. .It Bq Er ENOMEM Insufficient memory is available. .It Bq Er ERANGE The .Fa size argument is greater than zero but smaller than the length of the pathname plus 1. .El .Sh SEE ALSO .Xr chdir 2 , .Xr fchdir 2 , .Xr malloc 3 , .Xr strerror 3 .Sh STANDARDS The .Fn getwd and .Fn getcwd functions conform to .St -p1003.1-90 . The .St -p1003.1-2004 revision marked .Fn getwd as legacy and recommended the use of .Fn getcwd instead. The .St -p1003.1-2008 revision removed .Fn getwd from the specification. .Pp The ability to specify a .Dv NULL pointer and have .Fn getcwd allocate memory as necessary is an extension. .Sh HISTORY The .Fn getwd function appeared in .Bx 4.0 . .Sh SECURITY CONSIDERATIONS As .Fn getwd does not know the length of the supplied buffer, it is possible for a long (but valid) path to overflow the buffer and provide a means for an attacker to exploit the caller. .Fn getcwd should be used in place of .Fn getwd (the latter is only provided for compatibility purposes).