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_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_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.