ftw(3) BSD Library Functions Manual ftw(3)
NAME
ftw, nftw -- traverse (walk) a file tree
SYNOPSIS
#include <ftw.h>
int
ftw(const char *path,
int (*fn)(const char *, const struct stat *ptr, int flag),
int depth);
int
nftw(const char *path,
int (*fn)(const char *, const struct stat *ptr, int flag, struct FTW *),
int depth, 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 con-
tents 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 pro-
cesses the directory before the directory's contents.
The depth argument specifies the maximum number of file descriptors to
keep open while traversing the tree. It has no effect in this implemen-
tation.
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 FTW_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 depth argument is less than 1 or greater than
OPEN_MAX.
LEGACY ERRORS
The ftw() and nftw() functions are far more tolerant of symlink cycles
and are lax in reporting errors while accessing the initial path. When
nftw() is passed FTW_MOUNT, it will pass the mount point to the callback
function.
SEE ALSO
chdir(2), close(2), open(2), stat(2), fts(3), malloc(3), opendir(3),
readdir(3), compat(5)
STANDARDS
The ftw() and nftw() functions conform to IEEE Std 1003.1-2001
(``POSIX.1'') and Version 3 of the Single UNIX Specification (``SUSv3'').
HISTORY
Prior to MacOS X 10.4 ftw did not follow symlinks.
BUGS
The depth argument is currently ignored.
BSD May 20, 2003 BSD
Mac OS X 10.8 - Generated Mon Aug 27 18:38:02 CDT 2012