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\"     @(#)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).

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