NAME
ftw, nftw —
traverse (walk) a file
tree
SYNOPSIS
#include <ftw.h>
int
ftw(
const char *path,
int (*fn)(const char *, const struct stat *, int),
int maxfds);
int
nftw(
const char *path,
int (*fn)(const char *,
const struct stat *, int, struct FTW *),
int maxfds,
int flags);
DESCRIPTION
These functions
are provided for compatibility with legacy code. New code should use the
fts(3) functions.
The
ftw() and
nftw() functions traverse
(walk) the directory hierarchy rooted in
path. For each
object in the hierarchy, these functions call the function pointed to by
fn. The
ftw() function passes this
function a pointer to a NUL-terminated string containing the name of the
object, a pointer to a stat structure corresponding to the object, and an
integer flag. The
nftw() function passes the aforementioned
arguments plus a pointer to a
FTW
structure as defined
by
<ftw.h> (shown below):
struct FTW {
int base; /* offset of basename into pathname */
int level; /* directory depth relative to starting point */
};
Possible values for the flag passed to
fn are:
-
-
FTW_F
- A regular file.
-
-
FTW_D
- A directory being visited in pre-order.
-
-
FTW_DNR
- A directory which cannot be read. The directory will not be
descended into.
-
-
FTW_DP
- A directory being visited in post-order
(nftw() only).
-
-
FTW_NS
- A file for which no
stat(2) information was
available. The contents of the stat structure are undefined.
-
-
FTW_SL
- A symbolic link.
-
-
FTW_SLN
- A symbolic link with a non-existent target
(nftw() only).
The
ftw() function traverses the tree in pre-order. That is,
it processes the directory before the directory's contents.
The
maxfds argument specifies the maximum number of file
descriptors to keep open while traversing the tree. It has no effect in this
implementation.
The
nftw() function has an additional
flags argument with the following possible values:
-
-
FTW_PHYS
- Physical walk, don't follow symbolic links.
-
-
FTW_MOUNT
- The walk will not cross a mount point.
-
-
- FTW_DEPTH
- Process directories in post-order. Contents of a directory
are visited before the directory itself. By default,
nftw() traverses the tree in pre-order.
-
-
- FTW_CHDIR
- Change to a directory before reading it. By default,
nftw() will change its starting directory. The current
working directory will be restored to its original value before
nftw() returns.
RETURN VALUES
If the tree was traversed successfully, the
ftw() and
nftw() functions return 0. If the function pointed to by
fn returns a non-zero value,
ftw() and
nftw() will stop processing the tree and return the value
from
fn. Both functions return -1 if an error is
detected.
ERRORS
The
ftw() and
nftw() functions may fail and
set
errno for any of the errors specified for the
library functions
close(2),
open(2),
stat(2),
malloc(3),
opendir(3), and
readdir(3). If the
FGTW_CHDIR
flag is set, the
nftw()
function may fail and set
errno for any of the errors
specified for
chdir(2). In
addition, either function may fail and set
errno as
follows:
-
-
- [
EINVAL
]
- The maxfds argument is less than 1 or
greater than
OPEN_MAX
.
SEE ALSO
chdir(2),
close(2),
open(2),
stat(2),
fts(3),
malloc(3),
opendir(3),
readdir(3)
STANDARDS
The
ftw() and
nftw() functions conform to
IEEE Std 1003.1-2001 (“POSIX.1”). The
IEEE Std 1003.1-2008 (“POSIX.1”) revision
marked the function
ftw() as obsolete.
BUGS
The
maxfds argument is currently ignored.