ftw.scm

MSYS在windows下模拟了一个类unix的终端

;;;; ftw.scm --- filesystem tree walk

;;;; 	Copyright (C) 2002 Free Software Foundation, Inc.
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;;; Author: Thien-Thi Nguyen <[e-mail]>

;;; Commentary:

;; Two procedures are provided: `ftw' and `nftw'.

;; NOTE: The following description was adapted from the GNU libc info page, w/
;; significant modifications for a more "Schemey" interface.  Most noticible
;; are the inlining of `struct FTW *' parameters `base' and `level' and the
;; omission of `descriptors' parameters.

;; * Types
;;
;;    The X/Open specification defines two procedures to process whole
;; hierarchies of directories and the contained files.  Both procedures
;; of this `ftw' family take as one of the arguments a callback procedure
;; which must be of these types.
;;
;;  - Data Type: __ftw_proc_t
;;           (lambda (filename statinfo flag) ...) => status
;;
;;      Type for callback procedures given to the `ftw' procedure.  The
;;      first parameter is a filename, the second parameter is the
;;      vector value as returned by calling `stat' on FILENAME.
;;
;;      The last parameter is a symbol giving more information about
;;      FILENAM.  It can have one of the following values:
;;
;;     `regular'
;;           The current item is a normal file or files which do not fit
;;           into one of the following categories.  This means
;;           especially special files, sockets etc.
;;
;;     `directory'
;;           The current item is a directory.
;;
;;     `invalid-stat'
;;           The `stat' call to fill the object pointed to by the second
;;           parameter failed and so the information is invalid.
;;
;;     `directory-not-readable'
;;           The item is a directory which cannot be read.
;;
;;     `symlink'
;;           The item is a symbolic link.  Since symbolic links are
;;           normally followed seeing this value in a `ftw' callback
;;           procedure means the referenced file does not exist.  The
;;           situation for `nftw' is different.
;;
;;  - Data Type: __nftw_proc_t
;;           (lambda (filename statinfo flag base level) ...) => status
;;
;;      The first three arguments have the same as for the
;;      `__ftw_proc_t' type.  A difference is that for the third
;;      argument some additional values are defined to allow finer
;;      differentiation:
;;
;;     `directory-processed'
;;           The current item is a directory and all subdirectories have
;;           already been visited and reported.  This flag is returned
;;           instead of `directory' if the `depth' flag is given to
;;           `nftw' (see below).
;;
;;     `stale-symlink'
;;           The current item is a stale symbolic link.  The file it
;;           points to does not exist.
;;
;;      The last two parameters are described below.  They contain
;;      information to help interpret FILENAME and give some information
;;      about current state of the traversal of the directory hierarchy.
;;
;;     `base'
;;           The value specifies which part of the filename argument
;;           given in the first parameter to the callback procedure is
;;           the name of the file.  The rest of the string is the path
;;           to locate the file.  This information is especially
;;           important if the `chdir' flag for `nftw' was set since then
;;           the current directory is the one the current item is found
;;           in.
;;
;;     `level'
;;           While processing the directory the procedures tracks how
;;           many directories have been examined to find the current
;;           item.  This nesting level is 0 for the item given starting
;;           item (file or directory) and is incremented by one for each
;;           entered directory.
;;
;; * Procedure: (ftw filename proc . options)
;;   Do a filesystem tree walk starting at FILENAME using PROC.
;;
;;   The `ftw' procedure calls the callback procedure given in the
;;   parameter PROC for every item which is found in the directory
;;   specified by FILENAME and all directories below.  The procedure
;;   follows symbolic links if necessary but does not process an item
;;   twice.  If FILENAME names no directory this item is the only
;;   object reported by calling the callback procedure.
;;
;;   The filename given to the callback procedure is constructed by
;;   taking the FILENAME parameter and appending the names of all
;;   passed directories and then the local file name.  So the
;;   callback procedure can use this parameter to access the file.
;;   Before the callback procedure is called `ftw' calls `stat' for
;;   this file and passes the information up to the callback
;;   procedure.  If this `stat' call was not successful the failure is
;;   indicated by setting the flag argument of the callback procedure
;;   to `invalid-stat'.  Otherwise the flag is set according to the
;;   description given in the description of `__ftw_proc_t' above.
;;
;;   The callback procedure is expected to return non-#f to indicate
;;   that no error occurred and the processing should be continued.
;;   If an error occurred in the callback procedure or the call to
;;   `ftw' shall return immediately the callback procedure can return
;;   #f.  This is the only correct way to stop the procedure.  The
;;   program must not use `throw' or similar techniques to continue
;;   the program in another place.  [Can we relax this? --ttn]
;;
;;   The return value of the `ftw' procedure is #t if all callback
;;   procedure calls returned #t and all actions performed by the
;;   `ftw' succeeded.  If some procedure call failed (other than
;;   calling `stat' on an item) the procedure returns #f.  If a
;;   callback procedure returns a value other than #t this value is
;;   returned as the return value of `ftw'.
;;
;; * Procedure: (nftw filename proc . control-flags)
;;   Do a new-style filesystem tree walk starting at FILENAME using PROC.
;;   Various optional CONTROL-FLAGS alter the default behavior.
;;
;;   The `nftw' procedures works like the `ftw' procedures.  It calls
;;   the callback procedure PROC for all items it finds in the
;;   directory FILENAME and below.
;;
;;   The differences are that for one the callback procedure is of a
;;   different type.  It takes also `base' and `level' parameters as
;;   described above.
;;
;;   The second difference is that `nftw' takes additional optional
;;   arguments which are zero or more of the following symbols:
;;
;;   physical'
;;        While traversing the directory symbolic links are not
;;        followed.  I.e., if this flag is given symbolic links are
;;        reported using the `symlink' value for the type parameter
;;        to the callback procedure.  Please note that if this flag is
;;        used the appearance of `symlink' in a callback procedure
;;        does not mean the referenced file does not exist.  To
;;        indicate this the extra value `stale-symlink' exists.
;;
;;   mount'
;;        The callback procedure is only called for items which are on
;;        the same mounted filesystem as the directory given as the