NAME
getcwd,
getwd —
get
working directory pathname
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <unistd.h>
char *
getcwd(
char
*buf,
size_t size);
char *
getwd(
char
*buf);
DESCRIPTION
The
getcwd() function copies the absolute pathname of the
current working directory into the memory referenced by
buf and returns a pointer to
buf.
The
size argument is the size, in bytes, of the array
referenced by
buf.
If
buf is
NULL
, space is allocated
as necessary to store the pathname. This space may later be
free(3)'d.
The function
getwd() is a compatibility routine which calls
getcwd() with its
buf argument and a
size of
MAXPATHLEN
(as defined in the include file
<sys/param.h>). Obviously,
buf should be at least
MAXPATHLEN
bytes in length.
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
(‘
.
’) and use the
fchdir(2) function to return.
RETURN VALUES
Upon successful completion, a pointer to the pathname is returned. Otherwise a
NULL
pointer is returned and the global variable
errno is set to indicate the error. In addition,
getwd() copies the error message associated with
errno into the memory referenced by
buf.
ERRORS
The
getcwd() function will fail if:
-
-
- [
EACCES
]
- Read or search permission was denied for a component of the
pathname.
-
-
- [
EINVAL
]
- The size argument is zero.
-
-
- [
ENOENT
]
- A component of the pathname no longer exists.
-
-
- [
ENOMEM
]
- Insufficient memory is available.
-
-
- [
ERANGE
]
- The size argument is greater than
zero but smaller than the length of the pathname plus 1.
SEE ALSO
chdir(2),
fchdir(2),
malloc(3),
strerror(3)
STANDARDS
The
getwd() and
getcwd() functions conform
to
IEEE Std 1003.1-1990 (“POSIX.1”). The
IEEE Std 1003.1-2004 (“POSIX.1”) revision
marked
getwd() as legacy and recommended the use of
getcwd() instead. The
IEEE Std 1003.1-2008
(“POSIX.1”) revision removed
getwd() from
the specification.
The ability to specify a
NULL
pointer and have
getcwd() allocate memory as necessary is an extension.
HISTORY
The
getwd() function appeared in
4.0BSD.
SECURITY CONSIDERATIONS
As
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.
getcwd() should
be used in place of
getwd() (the latter is only provided for
compatibility purposes).