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;;; -*- Log: code.log; Package: Lisp -*-
;;; **********************************************************************
;;; This code was written as part of the CMU Common Lisp project at
;;; Carnegie Mellon University, and has been placed in the public domain.
;;; If you want to use this code or any part of CMU Common Lisp, please contact
;;; Scott Fahlman or slisp-group@cs.cmu.edu.
;;;
(ext:file-comment
  "$Header: /Volumes/share2/src/cmucl/cvs2git/cvsroot/src/code/filesys.lisp,v 1.81 2004/06/02 14:46:08 rtoy Exp $")
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;;; **********************************************************************
;;;
;;; File system interface functions.  This file is pretty UNIX specific.
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;;;
;;; Written by William Lott
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;;;
;;; **********************************************************************
(export '(truename probe-file user-homedir-pathname directory
          rename-file delete-file file-write-date file-author))
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(use-package "EXTENSIONS")

(in-package "EXTENSIONS")
(export '(print-directory complete-file ambiguous-files default-directory
	  purge-backup-files file-writable unix-namestring))
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;;;; Unix pathname host support.
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;;; Unix namestrings have the following format:
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;;;
;;; namestring := [ directory ] [ file [ type [ version ]]]
;;; directory := [ "/" | search-list ] { file "/" }*
;;; search-list := [^:/]*:
;;; file := [^/]*
;;; type := "." [^/.]*
;;; version := ".*" | ".~" ([0-9]+ | "*") "~"
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;;;
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;;; Note: this grammar is ambiguous.  The string foo.bar.~5~ can be parsed
;;; as either just the file specified or as specifying the file, type, and
;;; version.  Therefore, we use the following rules when confronted with
;;; an ambiguous file.type.version string:
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;;;
;;; - If the first character is a dot, it's part of the file.  It is not
;;; considered a dot in the following rules.
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;;;
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;;; - If there is only one dot, it separates the file and the type.
;;;
;;; - If there are multiple dots and the stuff following the last dot
;;; is a valid version, then that is the version and the stuff between
;;; the second to last dot and the last dot is the type.
;;;
;;; Wildcard characters:
;;;
;;; If the directory, file, type components contain any of the following
;;; characters, it is considered part of a wildcard pattern and has the
;;; following meaning.
;;;
;;; ? - matches any character
;;; * - matches any zero or more characters.
;;; [abc] - matches any of a, b, or c.
;;; {str1,str2,...,strn} - matches any of str1, str2, ..., or strn.
;;;
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;;; Any of these special characters can be preceded by a backslash to
;;; cause it to be treated as a regular character.
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;;;

(defun remove-backslashes (namestr start end)
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  "Remove any occurrences of \\ from the string because we've already
   checked for whatever may have been backslashed."
  (declare (type simple-base-string namestr)
	   (type index start end))
  (let* ((result (make-string (- end start)))
	 (dst 0)
	 (quoted nil))
    (do ((src start (1+ src)))
	((= src end))
      (cond (quoted
	     (setf (schar result dst) (schar namestr src))
	     (setf quoted nil)
	     (incf dst))
	    (t
	     (let ((char (schar namestr src)))
	       (cond ((char= char #\\)
		      (setq quoted t))
		     (t
		      (setf (schar result dst) char)
		      (incf dst)))))))
    (when quoted
      (error 'namestring-parse-error
	     :complaint "Backslash in bad place."
	     :namestring namestr
	     :offset (1- end)))
    (shrink-vector result dst)))

(defvar *ignore-wildcards* nil)

(defun maybe-make-pattern (namestr start end)
  (declare (type simple-base-string namestr)
	   (type index start end))
  (if *ignore-wildcards*
      (subseq namestr start end)
      (collect ((pattern))
	(let ((quoted nil)
	      (any-quotes nil)
	      (last-regular-char nil)
	      (index start))
	  (flet ((flush-pending-regulars ()
		   (when last-regular-char
		     (pattern (if any-quotes
				  (remove-backslashes namestr
						      last-regular-char
						      index)
				  (subseq namestr last-regular-char index)))
		     (setf any-quotes nil)
		     (setf last-regular-char nil))))
	    (loop
	      (when (>= index end)
		(return))
	      (let ((char (schar namestr index)))
		(cond (quoted
		       (incf index)
		       (setf quoted nil))
		      ((char= char #\\)
		       (setf quoted t)
		       (setf any-quotes t)
		       (unless last-regular-char
			 (setf last-regular-char index))
		       (incf index))
		      ((char= char #\?)
		       (flush-pending-regulars)
		       (pattern :single-char-wild)
		       (incf index))
		      ((char= char #\*)
		       (flush-pending-regulars)
		       (pattern :multi-char-wild)
		       (incf index))
		      ((char= char #\[)
		       (flush-pending-regulars)
		       (let ((close-bracket
			      (position #\] namestr :start index :end end)))
			 (unless close-bracket
			   (error 'namestring-parse-error
				  :complaint "``['' with no corresponding ``]''"
				  :namestring namestr
				  :offset index))
			 (pattern (list :character-set
					(subseq namestr
						(1+ index)
						close-bracket)))
			 (setf index (1+ close-bracket))))
		      (t
		       (unless last-regular-char
			 (setf last-regular-char index))
		       (incf index)))))
	    (flush-pending-regulars)))
	(cond ((null (pattern))
	       "")
	      ((null (cdr (pattern)))
	       (let ((piece (first (pattern))))
		 (typecase piece
		   ((member :multi-char-wild) :wild)
		   (simple-string piece)
		   (t
		    (make-pattern (pattern))))))
;;; extract-name-type-and-version  --  Internal.
;;;
(defun extract-name-type-and-version (namestr start end)
  (declare (type simple-base-string namestr)
	   (type index start end))
  (labels
      ((explicit-version (namestr start end)
	 (cond ((or (< (- end start) 5)
		    (char/= (schar namestr (1- end)) #\~))
		;; No explicit version given, so return NIL to
		;; indicate we don't want file versions, unless
		;; requested in other ways.
		(values nil end))
	       ((and (char= (schar namestr (- end 2)) #\*)
		     (char= (schar namestr (- end 3)) #\~)
		     (char= (schar namestr (- end 4)) #\.))
		(values :wild (- end 4)))
	       (t
		(do ((i (- end 2) (1- i)))
		    ((< i (+ start 2)) (values :newest end))
		  (let ((char (schar namestr i)))
		    (when (eql char #\~)
		      (return (if (char= (schar namestr (1- i)) #\.)
				  (values (parse-integer namestr :start (1+ i)
							 :end (1- end))
					  (1- i))
				  (values :newest end))))
		    (unless (char<= #\0 char #\9)
		      (return (values :newest end))))))))
       (any-version (namestr start end)
	 ;; process end of string looking for a version candidate.
	 (multiple-value-bind (version where)
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	     (explicit-version namestr start end)
	   (cond ((not (eq version :newest))
		  (values version where))
		 ((and (>= (- end 2) start)
		       (char= (schar namestr (- end 1)) #\*)
		       (char= (schar namestr (- end 2)) #\.)
		       (find #\. namestr
			     :start (min (1+ start) (- end 2))
			     :end (- end 2)))
		  (values :wild (- end 2)))
		 (t (values version where)))))
       (any-type (namestr start end)
	 ;; Process end of string looking for a type. A leading "."
	 ;; is part of the name.
	 (let ((where (position #\. namestr
				:start (min (1+ start) end)
				:end end :from-end t)))
	   (when where
	     (values where end))))
       (any-name (namestr start end)
	 (declare (ignore namestr))
	 (values start end)))
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    (multiple-value-bind (version vstart)
	(any-version namestr start end)
      (multiple-value-bind (tstart tend)
	  (any-type namestr start vstart)
	(multiple-value-bind (nstart nend)
	    (any-name namestr start (or tstart vstart))
	  (values
	   (maybe-make-pattern namestr nstart nend)
	   (and tstart (maybe-make-pattern namestr (1+ tstart) tend))
	   version))))))
;;; Take a string and return a list of cons cells that mark the char
;;; separated subseq. The first value t if absolute directories location.
;;;
(defun split-at-slashes (namestr start end)
  (declare (type simple-base-string namestr)
	   (type index start end))
  (let ((absolute (and (/= start end)
		       (char= (schar namestr start) #\/))))
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    ;; Next, split the remainder into slash separated chunks.
	(let ((slash (position #\/ namestr :start start :end end)))
	  (pieces (cons start (or slash end)))
	  (unless slash
      (values absolute (pieces)))))

(defun maybe-extract-search-list (namestr start end)
  (declare (type simple-base-string namestr)
	   (type index start end))
  (let ((quoted nil))
    (do ((index start (1+ index)))
	((= index end)
	 (values nil start))
      (if quoted
	  (setf quoted nil)
	  (case (schar namestr index)
	    (#\\
	     (setf quoted t))
	    (#\:
	     (return (values (remove-backslashes namestr start index)
			     (1+ index)))))))))

(defun parse-unix-namestring (namestr start end)
  (declare (type simple-base-string namestr)
	   (type index start end))
  (multiple-value-bind
      (absolute pieces)
      (split-at-slashes namestr start end)
    (let ((search-list
	   (if absolute
	       nil
	       (let ((first (car pieces)))
		 (multiple-value-bind
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		       (search-list new-start)
		     (maybe-extract-search-list namestr
						(car first) (cdr first))
		   (when search-list
		     (setf absolute t)
		     (setf (car first) new-start))
		   search-list)))))
      (multiple-value-bind
	  (name type version)
	  (let* ((tail (car (last pieces)))
		 (tail-start (car tail))
		 (tail-end (cdr tail)))
	    (unless (= tail-start tail-end)
	      (setf pieces (butlast pieces))
	      (extract-name-type-and-version namestr tail-start tail-end)))
	;; PVE: Make sure there are no illegal characters in the name
	;; such as #\Null and #\/.
	(when (and (stringp name)
                   (find-if #'(lambda (x)
				(or (char= x #\Null) (char= x #\/)))
			    name))
	  (error 'parse-error))
	;; Now we have everything we want.  So return it.
	(values nil ; no host for unix namestrings.
		nil ; no devices for unix namestrings.
		(collect ((dirs))
		  (when search-list
		    (dirs (intern-search-list search-list)))
		  (dolist (piece pieces)
		    (let ((piece-start (car piece))
			  (piece-end (cdr piece)))
		      (unless (= piece-start piece-end)
			(cond ((string= namestr ".." :start1 piece-start
					:end1 piece-end)
			       (dirs :up))
			      ((string= namestr "**" :start1 piece-start
					:end1 piece-end)
			       (dirs :wild-inferiors))
			      (t
			       (dirs (maybe-make-pattern namestr
							 piece-start
							 piece-end)))))))
		  (cond (absolute
			 (cons :absolute (dirs)))
			((dirs)
			 (cons :relative (dirs)))
			(t
			 nil)))
		name
		type
		version)))))

(defun unparse-unix-host (pathname)
  (declare (type pathname pathname)
	   (ignore pathname))
  ;; this host designator needs to be recognized as a physical host in
  ;; PARSE-NAMESTRING. Until sbcl-0.7.3.x, we had "Unix" here, but
  ;; that's a valid Logical Hostname, so that's a bad choice. -- CSR,
  "")

(defun unparse-unix-piece (thing)
  (etypecase thing
    (simple-string
     (let* ((srclen (length thing))
	    (dstlen srclen))
       (dotimes (i srclen)
	 (case (schar thing i)
	   ((#\* #\? #\[)
	    (incf dstlen))))
       (let ((result (make-string dstlen))
	     (dst 0))
	 (dotimes (src srclen)
	   (let ((char (schar thing src)))
	     (case char
	       ((#\* #\? #\[)
		(setf (schar result dst) #\\)
		(incf dst)))
	     (setf (schar result dst) char)
	     (incf dst)))
	 result)))
    (pattern
     (collect ((strings))
       (dolist (piece (pattern-pieces thing))
	 (etypecase piece
	   (simple-string
	    (strings piece))
	   (symbol
	      (:multi-char-wild
	       (strings "*"))
	      (:single-char-wild
	   (cons
	    (case (car piece)
	      (:character-set
	       (strings "[")
	       (strings "]"))
	      (t
	       (error "Invalid pattern piece: ~S" piece))))))
       (apply #'concatenate
	      'simple-string
	      (strings))))))

(defun unparse-unix-directory-list (directory)
  (declare (type list directory))
  (collect ((pieces))
    (when directory
      (ecase (pop directory)
	(:absolute
	 (cond ((search-list-p (car directory))
		(pieces (search-list-name (pop directory)))
		(pieces ":"))
	       (t
		(pieces "/"))))
	(:relative
	 ;; Nothing special.
	 ))
      (dolist (dir directory)
	(typecase dir
	  ((member :up)
	   (pieces "../"))
	  ((member :back)
	   (error ":BACK cannot be represented in namestrings."))
	  ((member :wild-inferiors)
	   (pieces "**/"))
	  ((or simple-string pattern)
	   (pieces (unparse-unix-piece dir))
	   (pieces "/"))
	  (t
	   (error "Invalid directory component: ~S" dir)))))
    (apply #'concatenate 'simple-string (pieces))))

(defun unparse-unix-directory (pathname)
  (declare (type pathname pathname))
  (unparse-unix-directory-list (%pathname-directory pathname)))
(defun unparse-unix-file (pathname)
  (declare (type pathname pathname))
  (collect ((strings))
    (let* ((name (%pathname-name pathname))
	   (type (%pathname-type pathname))
	   (type-supplied (not (or (null type) (eq type :unspecific))))
	   (logical-p (logical-pathname-p pathname))
	   (version (%pathname-version pathname))
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	   (version-supplied (not (or (null version)
				      (member version '(:newest
							:unspecific))))))
      (when name
	(strings (unparse-unix-piece name)))
      (when type-supplied
	(unless name
	  (error "Cannot specify the type without a file: ~S" pathname))
	(strings ".")
	(strings (unparse-unix-piece type)))
      (when version-supplied
	(strings (if (eq version :wild)
		     (if logical-p ".*" ".~*~")
		     (format nil (if logical-p ".~D" ".~~~D~~")
			     version)))))
    (and (strings) (apply #'concatenate 'simple-string (strings)))))

(defun unparse-unix-namestring (pathname)
  (declare (type pathname pathname))
  (concatenate 'simple-string
	       (unparse-unix-directory pathname)
	       (unparse-unix-file pathname)))

(defun unparse-unix-enough (pathname defaults)
  (declare (type pathname pathname defaults))
  (flet ((lose ()
	   (error "~S cannot be represented relative to ~S"
		  pathname defaults)))
    (collect ((strings))
      (let* ((pathname-directory (%pathname-directory pathname))
	     (defaults-directory (%pathname-directory defaults))
	     (prefix-len (length defaults-directory))
	     (result-dir
	      (cond ((null pathname-directory)
		     ;; No directory, so relative to default.
		     (list :relative))
		    ((eq (first pathname-directory) :relative)
		     ;; Relative directory so relative to default.
		     pathname-directory)
		    ((and (> prefix-len 1)
			      (>= (length pathname-directory) prefix-len)
			      (compare-component (subseq pathname-directory
							 0 prefix-len)
						 defaults-directory))
		     ;; Pathname starts with a prefix of default.  So just
		     ;; use a relative directory from then on out.
		     (cons :relative (nthcdr prefix-len pathname-directory)))
		    ((eq (car pathname-directory) :absolute)
		     ;; We are an absolute pathname, so we can just use it.
		     pathname-directory)
		    (t
		     ;; We are a relative directory.  So we lose.
		     (lose)))))
	(strings (unparse-unix-directory-list result-dir)))
      (let* ((pathname-version (%pathname-version pathname))
	     (version-needed (and pathname-version
				  (not (eq pathname-version :newest))))
	     (pathname-type (%pathname-type pathname))
	     (type-needed (or version-needed
			      (and pathname-type
				   (not (eq pathname-type :unspecific)))))
	     (pathname-name (%pathname-name pathname))
	     (name-needed (or type-needed
			      (and pathname-name
				   (not (compare-component pathname-name
							   (%pathname-name
							    defaults)))))))
	(when name-needed
	  (unless pathname-name (lose))
	  (strings (unparse-unix-piece pathname-name)))
	(when type-needed
	  (when (or (null pathname-type) (eq pathname-type :unspecific))
	    (lose))
	  (strings ".")
	  (strings (unparse-unix-piece pathname-type)))
	(when version-needed
	  (typecase pathname-version
	    ((member :wild)
	     (strings (format nil ".~~~D~~" pathname-version)))
	    (t
	     (lose)))))
      (apply #'concatenate 'simple-string (strings)))))


(defstruct (unix-host
	    (:include host
		      (:parse #'parse-unix-namestring)
		      (:unparse #'unparse-unix-namestring)
		      (:unparse-host #'unparse-unix-host)
		      (:unparse-directory #'unparse-unix-directory)
		      (:unparse-file #'unparse-unix-file)
		      (:unparse-enough #'unparse-unix-enough)
		      (:customary-case :lower))
	    (:make-load-form-fun make-unix-host-load-form))
  )

(defvar *unix-host* (make-unix-host))

(defun make-unix-host-load-form (host)
  (declare (ignore host))
  '*unix-host*)
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;;;; Wildcard matching stuff.

(defmacro enumerate-matches ((var pathname &optional result
				  &key (verify-existance t) (follow-links t))
			     &body body)
  (let ((body-name (gensym)))
    `(block nil
       (flet ((,body-name (,var)
		,@body))
	 (%enumerate-matches (pathname ,pathname)
			     ,verify-existance ,follow-links
(defun %enumerate-matches (pathname verify-existance follow-links function)
  (when (pathname-type pathname)
    (unless (pathname-name pathname)
      (error "Cannot supply a type without a name:~%  ~S" pathname)))
  (let ((directory (pathname-directory pathname)))
    (if directory
	(ecase (car directory)
	  (:absolute
	   (%enumerate-directories "/" (cdr directory) pathname
				   verify-existance follow-links
				   nil function))
	  (:relative
	   (%enumerate-directories "" (cdr directory) pathname
				   verify-existance follow-links
				   nil function)))
	(%enumerate-files "" pathname verify-existance function))))
;;; %enumerate-directories  --   Internal
;;;
;;; The directory node and device numbers are maintained for the current path
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;;; during the search for the detection of path loops upon :wild-inferiors.
;;;
(defun %enumerate-directories (head tail pathname verify-existance
			       follow-links nodes function)
  (declare (simple-string head))
  (macrolet ((unix-xstat (name)
	       `(if follow-links
		    (unix:unix-stat ,name)
		    (unix:unix-lstat ,name)))
	     (with-directory-node-noted ((head) &body body)
	       `(multiple-value-bind (res dev ino mode)
		    (unix-xstat ,head)
		  (when (and res (eql (logand mode unix:s-ifmt) unix:s-ifdir))
		    (let ((nodes (cons (cons dev ino) nodes)))
		      ,@body))))
	     (do-directory-entries ((name directory) &body body)
	       `(let ((dir (unix:open-dir ,directory)))
		  (when dir
		    (unwind-protect
			 (loop
			  (let ((,name (unix:read-dir dir)))
			    (cond ((null ,name)
				   (return))
				  ((string= ,name "."))
				  ((string= ,name ".."))
				  (t
				   ,@body))))
		      (unix:close-dir dir))))))
    (if tail
	(let ((piece (car tail)))
	  (etypecase piece
	    (simple-string
	     (let ((head (concatenate 'string head piece)))
	       (with-directory-node-noted (head)
		 (%enumerate-directories (concatenate 'string head "/")
					 (cdr tail) pathname
					 verify-existance follow-links
					 nodes function))))
	    ((member :wild-inferiors)
	     (%enumerate-directories head (rest tail) pathname
				     verify-existance follow-links
				     nodes function)
	     (do-directory-entries (name head)
	       (let ((subdir (concatenate 'string head name)))
		 (multiple-value-bind (res dev ino mode)
		     (unix-xstat subdir)
		   (declare (type (or fixnum null) mode))
		   (when (and res (eql (logand mode unix:s-ifmt) unix:s-ifdir))
		     (unless (dolist (dir nodes nil)
			       (when (and (eql (car dir) dev)
					  (eql (cdr dir) ino))
				 (return t)))
		       (let ((nodes (cons (cons dev ino) nodes))
			     (subdir (concatenate 'string subdir "/")))
			 (%enumerate-directories subdir tail pathname
						 verify-existance follow-links
						 nodes function))))))))
	    ((or pattern (member :wild))
	     (do-directory-entries (name head)
	       (when (or (eq piece :wild) (pattern-matches piece name))
		 (let ((subdir (concatenate 'string head name)))
		   (multiple-value-bind (res dev ino mode)
		       (unix-xstat subdir)
		     (declare (type (or fixnum null) mode))
		     (when (and res
				(eql (logand mode unix:s-ifmt) unix:s-ifdir))
		       (let ((nodes (cons (cons dev ino) nodes))
			     (subdir (concatenate 'string subdir "/")))
			 (%enumerate-directories subdir (rest tail) pathname
						 verify-existance follow-links
						 nodes function))))))))
	    ((member :up)
	     (let ((head (concatenate 'string head "..")))
	       (with-directory-node-noted (head)
		 (%enumerate-directories (concatenate 'string head "/")
					 (rest tail) pathname
					 verify-existance follow-links
					 nodes function))))))
	(%enumerate-files head pathname verify-existance function))))

(defun %enumerate-files (directory pathname verify-existance function)
  (declare (simple-string directory))
  (let ((name (%pathname-name pathname))
	(type (%pathname-type pathname))
	(version (%pathname-version pathname)))
    (cond ((member name '(nil :unspecific))
	   (when (or (not verify-existance)
		     (unix:unix-file-kind directory))
	     (funcall function directory)))
	  ((or (pattern-p name)
	       (pattern-p type)
	       (eq name :wild)
	       (eq type :wild))
	   (let ((dir (unix:open-dir directory)))
		     (let ((file (unix:read-dir dir)))
			   (unless (or (string= file ".")
				       (string= file ".."))
			     (multiple-value-bind
				 (file-name file-type file-version)
				 (let ((*ignore-wildcards* t))
				   (extract-name-type-and-version
				    file 0 (length file)))
			       ;; Match also happens if the file has
			       ;; no explicit version and we're asking
			       ;; for version :NEWEST, since that's
			       ;; what no version means.
			       (when (and (components-match file-name name)
					  (components-match file-type type)
					  (or (components-match file-version
								version)
					      (and (eq file-version nil)
						   (eq version :newest))))
				 (funcall function
					  (concatenate 'string
						       directory
						       file)))))
		 (unix:close-dir dir)))))
	  (t
	   (let ((file (concatenate 'string directory name)))
	     (unless (or (null type) (eq type :unspecific))
	       (setf file (concatenate 'string file "." type)))
	     (unless (member version '(nil :newest :wild :unspecific))
	       (setf file (concatenate 'string file ".~"
				       (quick-integer-to-string version)
				       "~")))
	     (when (or (not verify-existance)
		       (unix:unix-file-kind file t))
	       (funcall function file)))))))
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(defun quick-integer-to-string (n)
  (cond ((not (fixnump n))
	 (write-to-string n :base 10 :radix nil))
	((zerop n) "0")
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	((eql n 1) "1")
	((minusp n)
	 (concatenate 'simple-string "-"
		      (the simple-string (quick-integer-to-string (- n)))))
	(t
	 (do* ((len (1+ (truncate (integer-length n) 3)))
	       (res (make-string len))
	       (i (1- len) (1- i))
	       (q n)
	       (r 0))
	      ((zerop q)
	       (incf i)
	       (replace res res :start2 i :end2 len)
	       (shrink-vector res (- len i)))
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	   (declare (simple-string res)
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	   (multiple-value-setq (q r) (truncate q 10))
	   (setf (schar res i) (schar "0123456789" r))))))

(defun unix-namestring (pathname &optional (for-input t) executable-only)
  "Convert PATHNAME into a string that can be used with UNIX system calls.
   Search-lists and wild-cards are expanded. If optional argument
   FOR-INPUT is true and PATHNAME doesn't exist, NIL is returned.
   If optional argument EXECUTABLE-ONLY is true, NIL is returned
   unless an executable version of PATHNAME exists."
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  ;; toy@rtp.ericsson.se: Let unix-namestring also handle logical
  ;; pathnames too.
  (let ((path (let ((lpn (pathname pathname)))
		(if (logical-pathname-p lpn)
		    (namestring (translate-logical-pathname lpn))
		    pathname))))
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      (pathname path)
      (enumerate-matches (name pathname nil :verify-existance for-input
			       :follow-links t)
	(when (or (not executable-only)
		  (and (eq (unix:unix-file-kind name) :file)
		       (unix:unix-access name unix:x_ok)))
	  (names name)))
      (let ((names (names)))
	(when names
	  (when (cdr names)
	    (error 'simple-file-error
		   :format-control "~S is ambiguous:~{~%  ~A~}"
		   :format-arguments (list pathname names)))
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	  (return (car names))))))))
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;;;; TRUENAME and PROBE-FILE.
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;;; Truename  --  Public
;;;
;;; Another silly file function trivially different from another function.
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;;;
(defun truename (pathname)
  "Return the pathname for the actual file described by the pathname
  An error of type file-error is signalled if no such file exists,
  or the pathname is wild."
  (if (wild-pathname-p pathname)
      (error 'simple-file-error
	     :format-control "Bad place for a wild pathname."
	     :pathname pathname)
      (let ((result (probe-file pathname)))
	(unless result
	  (error 'simple-file-error
		 :pathname pathname
		 :format-control "The file ~S does not exist."
		 :format-arguments (list (namestring pathname))))
	result)))
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;;; Probe-File  --  Public
;;;
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;;; If PATHNAME exists, return its truename, otherwise NIL.
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;;;
(defun probe-file (pathname)
  "Return a pathname which is the truename of the file if it exists, NIL
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  otherwise. An error of type file-error is signalled if pathname is wild."
  (if (wild-pathname-p pathname)
      (error 'simple-file-error 
	     :pathname pathname
	     :format-control "Bad place for a wild pathname.")
      (let ((namestring (unix-namestring (merge-pathnames pathname) t)))
	(when (and namestring (unix:unix-file-kind namestring))
	  (let ((truename (unix:unix-resolve-links
			   (unix:unix-maybe-prepend-current-directory
			    namestring))))
	    (when truename
	      (let ((*ignore-wildcards* t))
		(pathname (unix:unix-simplify-pathname truename)))))))))
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;;;; Other random operations.
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;;; Rename-File  --  Public
;;;
(defun rename-file (file new-name)
  "Rename File to have the specified New-Name.  If file is a stream open to a
  file, then the associated file is renamed."
  (let* ((original (truename file))
	 (original-namestring (unix-namestring original t))
	 (new-name (merge-pathnames new-name original))
	 (new-namestring (unix-namestring new-name nil)))
      (error 'simple-file-error
	     :pathname new-name
	     :format-control "~S can't be created."
	     :format-arguments (list new-name)))
    (multiple-value-bind (res error)
			 (unix:unix-rename original-namestring
	(error 'simple-file-error
	       :pathname new-name
	       :format-control "Failed to rename ~A to ~A: ~A"
	       :format-arguments (list original new-name
				       (unix:get-unix-error-msg error))))
      (when (streamp file)
	(file-name file new-namestring))
      (values new-name original (truename new-name)))))
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;;; Delete-File  --  Public
;;;
;;;    Delete the file, Man.
;;;
(defun delete-file (file)
  "Delete the specified file."
  (let ((namestring (unix-namestring file t)))
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    (when (streamp file)
      ;; Close the file, but don't try to revert or anything.  We want
      ;; to delete it, man!
      (close file))
      (error 'simple-file-error
	     :pathname file
	     :format-control "~S doesn't exist."
	     :format-arguments (list file)))
    (multiple-value-bind (res err) (unix:unix-unlink namestring)
	(error 'simple-file-error
	       :pathname namestring
	       :format-control "Could not delete ~A: ~A."
	       :format-arguments (list namestring
				       (unix:get-unix-error-msg err))))))
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  t)
;;; Purge-Backup-Files  --  Public
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;;;
;;;    Purge old file versions
;;;
(defun purge-backup-files (pathname &optional (keep 0))
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  "Delete old versions of files matching the given Pathname,
optionally keeping some of the most recent old versions."
  (declare (type (or pathname string stream) pathname)
	   (type (integer 0 *) keep))
  (let ((hash (make-hash-table :test 'equal)))
    (enumerate-search-list
	(path (make-pathname :version :wild :defaults pathname))
      (clrhash hash)
      (enumerate-matches (name path nil :follow-links nil)
	(let ((dot (position #\. name :from-end t))
	      (len (length name)))
	  (when (and dot
		     (> len (+ dot 3))
		     (char= (char name (1+ dot)) #\~)
		     (char= (char name (1- len)) #\~)
		     (eq (unix:unix-file-kind name) :file))
	    (multiple-value-bind (version next)
		(parse-integer name :start (+ dot 2) :end (1- len)
			       :junk-allowed t)
	      (when (and version (= next (1- len)))
		(push (cons version name)
		      (gethash (subseq name 0 dot) hash '())))))))
      (maphash (lambda (key value)
		 (declare (ignore key))
		 (mapc #'unix:unix-unlink
		       (mapcar #'cdr (nthcdr keep
					     (sort value #'> :key #'car)))))
	       hash))))

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;;; User-Homedir-Pathname  --  Public
;;;
;;;    Return Home:, which is set up for us at initialization time.
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;;;
(defun user-homedir-pathname (&optional host)
  "Returns the home directory of the logged in user as a pathname.
  This is obtained from the logical name \"home:\"."
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  (declare (ignore host))
  #p"home:")
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;;; File-Write-Date  --  Public
;;;
(defun file-write-date (file)
  "Return file's creation date, or NIL if it doesn't exist.
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 An error of type file-error is signalled if file is a wild pathname"
  (if (wild-pathname-p file)
      (error 'simple-file-error 
	     :pathname file
	     :format-control "Bad place for a wild pathname.")
      (let ((name (unix-namestring file t)))
	(when name
	  (multiple-value-bind
	      (res dev ino mode nlink uid gid rdev size atime mtime)
	      (unix:unix-stat name)
	    (declare (ignore dev ino mode nlink uid gid rdev size atime))
	    (when res
	      (+ unix-to-universal-time mtime)))))))
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;;; File-Author  --  Public
;;;
(defun file-author (file)
  "Returns the file author as a string, or nil if the author cannot be
 determined.  Signals an error of type file-error if file doesn't exist,
 or file is a wild pathname."
  (if (wild-pathname-p file)
      (error 'simple-file-error
	     :format-control "Bad place for a wild pathname.")
      (let ((name (unix-namestring (pathname file) t)))
	(unless name
	  (error 'simple-file-error
		 :pathname file
		 :format-control "~S doesn't exist."
		 :format-arguments (list file)))
	(multiple-value-bind (winp dev ino mode nlink uid)
			     (unix:unix-stat name)
	  (declare (ignore dev ino mode nlink))
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	  (when winp
            (let ((user-info (unix:unix-getpwuid uid)))
              (when user-info
                (unix:user-info-name user-info))))))))
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;;;; DIRECTORY.

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;;;
(defun directory (pathname &key (all t) (check-for-subdirs t)
			   (truenamep t) (follow-links t))
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  "Returns a list of pathnames, one for each file that matches the given
   pathname.  Supplying :ALL as nil causes this to ignore Unix dot files.  This
   never includes Unix dot and dot-dot in the result.  If :TRUENAMEP is NIL,
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   then symbolic links in the result are not expanded, which is not the
   default because TRUENAME does follow links and the result pathnames are
   defined to be the TRUENAME of the pathname (the truename of a link may well
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   be in another directory).  If FOLLOW-LINKS is NIL then symbolic links are
  (let ((results nil))
    (enumerate-search-list
	(pathname (merge-pathnames pathname
				   (make-pathname :name :wild
						  :type :wild
						  :version :wild
						  :defaults *default-pathname-defaults*)
      (enumerate-matches (name pathname nil :follow-links follow-links)
	(when (or all
		  (let ((slash (position #\/ name :from-end t)))
		    (or (null slash)
			(= (1+ slash) (length name))
			(char/= (schar name (1+ slash)) #\.))))
	  (push name results))))
    (let ((*ignore-wildcards* t))
      (mapcar #'(lambda (name)
		  (let ((name (if (and check-for-subdirs
				       (eq (unix:unix-file-kind name)
					   :directory))
				  (concatenate 'string name "/")
				  name)))
		    (if truenamep (truename name) (pathname name))))
	      (sort (delete-duplicates results :test #'string=) #'string<)))))
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;;; PRINT-DIRECTORY is exported from the EXTENSIONS package.
;;; 
(defun print-directory (pathname &optional stream &key all verbose return-list)
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  "Like Directory, but prints a terse, multi-column directory listing
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   instead of returning a list of pathnames.  When :all is supplied and
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   non-nil, then Unix dot files are included too (as ls -a).  When :verbose
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   is supplied and non-nil, then a long listing of miscellaneous
   information is output one file per line."
  (let ((*standard-output* (out-synonym-of stream))
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    (if verbose
	(print-directory-verbose pathname all return-list)