getcwd, getwd - get working directory pathname
Standard C Library (libc, -lc)
getcwd(char *buf, size_t size);
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
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.
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 getcwd() function conforms to ISO/IEC 9945-1:1990 (``POSIX.1''). The
ability to specify a NULL pointer and have getcwd() allocate memory as
necessary is an extension.
The getwd() function appeared in 4.0BSD.
SECURITY CONSIDERATIONS [Toc] [Back]
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).
BSD December 11, 1993 BSD
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