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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) func-tions. functions.
     tions.

     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 aforemen-tioned aforementioned
     tioned 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 depth 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 direc-tory. directory.
                tory.  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 addi-tion, addition,
     tion, 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