FreeBSD Man Pages

nftw(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 *, int),
	 int maxfds);

     int
     nftw(const char *path,
	 int (*fn)((const char *, const struct stat *, int, struct FTW *),
	 int maxfds, int flags);

DESCRIPTION

     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 maxfds 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_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 maxfds argument is less than 1.

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'').

HISTORY

     These functions first appeared in AT&T System V.3 UNIX.  Their first
     FreeBSD appearance was in FreeBSD 5.3.

BUGS

     The maxfds argument is currently ignored.

FreeBSD 5.4			 July 5, 2004			   FreeBSD 5.4

SPONSORED LINKS