FTW(3) FTW(3)
NAME
ftw - file tree walk
SYNOPSIS
#include <ftw.h>
int ftw(path, fn, depth)
char *path;
int (*fn)();
int depth;
#include <sys/types.h>
#include <sys/stat.h>
fn(name, statb, code, S)
char *name;
struct stat *statb;
struct FTW *S;
DESCRIPTION
Ftw recursively descends the directory hierarchy rooted in
path. For each entry in the hierarchy, ftw calls fn, passing
it information about the entry: a pointer to a null-
terminated pathname string, a pointer to a stat structure
(see stat(2)), and a pointer to the following structure.
struct FTW {
int quit; see below
int base; &name[base] points to basename
int level; recursion level (initially 0)
};
Possible values of code, defined in are
FTW_D Entry is a directory (before visiting descendants).
FTW_DP Entry is a directory (after visiting descendants).
FTW_SL Entry is a symbolic link.
FTW_F Entry is some other kind of file.
FTW_DNR Entry is a directory that cannot be read; no
descendants will be visited.
FTW_NS Lstat (see stat(2)) failed on name; contents of
statb are undefined
FTW_NSL Lstat succeeded, but stat failed; contents of statb
are undefined.
The tree traversal continues until the tree is exhausted or
fn returns a nonzero value. When the tree is exhausted, ftw
returns zero. When fn returns a nonzero value, ftw stops
and returns that value.
FTW(3) FTW(3)
Normally symbolic links are not followed. But if on a sym-
bolic link (FTW_SL) fn sets S->quit to FTW_FOLLOW, ftw will
next attempt to follow the link.
Ftw normally visits a readable directory twice, before and
after visiting its descendants. But if on a previsit
(FTW_D) fn sets S->quit to FTW_SKD, ftw will skip the
descendants and the postvisit (FTW_DP).
Ftw uses one file descriptor for each level in the tree up
to a maximum of depth (or 1, if depth<1) descriptors. Depth
must not exceed the number of available file descriptors;
small values of depth may cause ftw to run slowly, but will
not change its effect.
SEE ALSO
stat(2), directory(3)
DIAGNOSTICS
Ftw returns -1 with errno set to ENOMEM when malloc(3)
fails.
Errno is set appropriately when ftw calls fn with code
FTW_DNR, FTW_NS, or FTW_NSL.