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NetBSD 6.1.5 - man page for getwd (netbsd section 3)

GETCWD(3)			   BSD Library Functions Manual 			GETCWD(3)

     getcwd, getwd -- get working directory pathname

     Standard C Library (libc, -lc)

     #include <unistd.h>

     char *
     getcwd(char *buf, size_t size);

     char *
     getwd(char *buf);

     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 direc-
     tory 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

     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.

     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.

     chdir(2), fchdir(2), malloc(3), strerror(3)

     The getwd() and getcwd() functions conform to ISO/IEC 9945-1:1990 (``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

     The ability to specify a NULL pointer and have getcwd() allocate memory as necessary is an

     The getwd() function appeared in 4.0BSD.

     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 call-
     er.  getcwd() should be used in place of getwd() (the latter is only provided for compati-
     bility purposes).

BSD					  April 29, 2010				      BSD

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