FTW(3C)                                                   FTW(3C)



     NAME
          ftw - walk a file tree

     SYNOPSIS
          #include <ftw.h>

          int ftw (path, fn, depth)
          char *path;
          int (*fn) ( );
          int depth;

     DESCRIPTION
          ftw recursively descends the directory hierarchy rooted in
          path.  For each object in the hierarchy, ftw calls fn,
          passing it a pointer to a null-terminated character string
          containing the name of the object, a pointer to a stat
          structure [see stat(2)] containing information about the
          object, and an integer.  Possible values of the integer,
          defined in the <ftw.h> header file, are FTW_F for a file,
          FTW_D for a directory, FTW_DNR for a directory that cannot
          be read, and FTW_NS for an object for which stat could not
          successfully be executed.  If the integer is FTW_DNR,
          descendants of that directory will not be processed.  If the
          integer is FTW_NS, the stat structure will contain garbage.
          An example of an object that would cause FTW_NS to be passed
          to fn would be a file in a directory with read but without
          execute (search) permission.

          ftw visits a directory before visiting any of its
          descendants.

          The tree traversal continues until the tree is exhausted, an
          invocation of fn returns a nonzero value, or some error is
          detected within ftw (such as an I/O error).  If the tree is
          exhausted, ftw returns zero.  If fn returns a nonzero value,
          ftw stops its tree traversal and returns whatever value was
          returned by fn.  If ftw detects an error, it returns -1, and
          sets the error type in errno.

          ftw uses one file descriptor for each level in the tree.
          The depth argument limits the number of file descriptors so
          used.  If depth is zero or negative, the effect is the same
          as if it were 1.  Depth must not be greater than the number
          of file descriptors currently available for use.  ftw will
          run more quickly if depth is at least as large as the number
          of levels in the tree.

     SEE ALSO
          stat(2), malloc(3C).

     BUGS
          Because ftw is recursive, it is possible for it to terminate



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     FTW(3C)                                                   FTW(3C)



          with a memory fault when applied to very deep file
          structures.

     CAVEAT
          ftw uses malloc(3C) to allocate dynamic storage during its
          operation.  If ftw is forcibly terminated, such as by
          longjmp being executed by fn or an interrupt routine, ftw
          will not have a chance to free that storage, so it will
          remain permanently allocated.  A safe way to handle
          interrupts is to store the fact that an interrupt has
          occurred, and arrange to have fn return a nonzero value at
          its next invocation.

     ORIGIN
          AT&T V.3








































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