X-Git-Url: https://git.distorted.org.uk/~mdw/lisp/blobdiff_plain/443fcfc494ed940c60d94c70e3391bf3c79c915f..813da880d2d77f04ea623f426d543d298528f967:/safely.lisp

diff --git a/safely.lisp b/safely.lisp
index 8cd0f9a..9b39518 100644
--- a/safely.lisp
+++ b/safely.lisp
@@ -1,7 +1,5 @@
 ;;; -*-lisp-*-
 ;;;
-;;; $Id$
-;;;
 ;;; Safely modify collections of files
 ;;;
 ;;; (c) 2005 Straylight/Edgeware
@@ -24,26 +22,32 @@
 ;;; Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 
 (defpackage #:safely
-  (:use #:common-lisp #:mdw.base)
-  (:export #:safely #:safely-close #:safely-delete-file
-	   #:safely-open-output-stream #:safely-bail #:safely-commit
-	   #:safely-writing))
+  (:use #:common-lisp #:mdw.base))
 (in-package #:safely)
 
 #+(or cmu sbcl)
 (eval-when (:compile-toplevel :execute)
   (import #+cmu '(ext:unix-namestring unix:unix-link)
-	  #+sbcl '(sb-int:unix-namestring)))
+	  #+sbcl '(sb-ext:native-namestring)))
+#+cmu
+(progn
+  (declaim (inline unix-namestring))
+  (defun native-namestring (pathname &key as-file)
+    (declare (ignore as-file))
+    (unix-namestring pathname nil)))
 
-(defstruct (safely (:predicate safelyp))
+(export '(safely safelyp make-safely))
+(defstruct (safely (:predicate safelyp) (:constructor make-safely ()))
   "Stores information about how to commit or undo safe writes."
   (streams nil)
   (trail nil))
 
+(export 'safely-close)
 (defun safely-close (safe stream)
   "Make sure that STREAM is closed when SAFE is finished."
   (push stream (safely-streams safe)))
 
+(export 'safely-delete-file)
 (defun safely-delete-file (safe file)
   "Delete FILE when SAFE is committed."
   (push `(:delete ,file) (safely-trail safe)))
@@ -88,6 +92,7 @@
 	(when ret
 	  (return (values new ret)))))))
 
+(export 'safely-open-output-stream)
 (defun safely-open-output-stream (safe file &rest open-args)
   "Create an output stream which will be named FILE when SAFE is committed.
    Other OPEN-ARGS are passed to open."
@@ -104,10 +109,26 @@
 	  (safely-trail safe))
     stream))
 
+#+clisp
+(progn
+  (ffi:def-call-out %rename (:name "rename")
+    (:language :stdc)
+    (:library "libc.so.6")
+    (:arguments (from ffi:c-string)
+		(to ffi:c-string))
+    (:return-type ffi:int)))
+
 (declaim (inline rename))
 (defun rename (old new)
-  #-clisp (rename-file old new)
-  #+clisp (posix:copy-file old new :method :rename))
+  #-clisp
+  (let ((target (make-pathname :directory '(:relative)
+			       :defaults new)))
+    (rename-file old target))
+
+  #+clisp
+  (let ((rc (%rename (namestring old) (namestring new))))
+    (when (= rc -1)
+      (error "Failed to rename ~S to ~S: ~A" old new (posix:strerror)))))
 
 (defun delete-file-without-moaning (file)
   "Delete the FILE, ignoring errors."
@@ -138,6 +159,7 @@
   (setf (safely-streams safe) nil)
   (setf (safely-trail safe) nil))
 
+(export 'safely-bail)
 (defun safely-bail (safe)
   "Abort the operations in SAFE, unwinding all the things that have been
    done.  Streams are closed, new files are removed."
@@ -158,20 +180,22 @@
   ;; Use link(2) where available.
   (generate-fresh-file-name file tag
 			    (lambda (name)
-			      (let ((from (unix-namestring file t))
-				    (to (unix-namestring name nil)))
+			      (let ((from (native-namestring file
+							     :as-file t))
+				    (to (native-namestring name
+							   :as-file t)))
 				(and from to
 				     (unix-link from to)))))
 
   #+clisp
   (generate-fresh-file-name file tag
 			    (lambda (name)
-			      (>= (unix:link (namestring file) 
-					     (namestring name))
-				  0)))
-
+			      (posix:copy-file (namestring file)
+					       (namestring name)
+					       :method :hardlink
+					       :if-exists nil)))
 
-  #-(or cmu sbcl)
+  #-(or cmu sbcl clisp)
   ;; Otherwise just copy the file contents and hope for the best.
   (with-open-file (input file :element-type :default)
     (multiple-value-bind
@@ -195,6 +219,7 @@
 		     (return copy))))))
 	(close output)))))
 
+(export 'safely-commit)
 (defun safely-commit (safe)
   "Commit SAFE.  The files deleted by safely-delete-file are deleted; the
    files created by safely-open-output-stream are renamed over the old
@@ -210,29 +235,30 @@
 	  (loop
 	    (unless trail
 	      (return))
-	      (let ((job (pop trail)))
-		(ecase (car job)
-		  (:shunt (destructuring-bind (tag new file) job
-			    (declare (ignore tag))
-			    (push `(:rmtmp ,new) revert)
-			    (if (probe-file file)
-				(let ((old (safe-copy file "old")))
-				  (push `(:rmtmp ,old) cleanup)
-				  (push `(:revert ,old ,file) revert))
-				(push `(:rmtmp ,file) revert))
-			    (rename new file)))
-		  (:delete (destructuring-bind (tag file) job
-			     (declare (ignore tag))
-			     (let ((old (safe-copy file "delete")))
-			       (push `(:revert ,old ,file) revert)
-			       (push `(:rmtmp ,old) cleanup)
-			       (delete-file file)))))))
+	    (let ((job (pop trail)))
+	      (ecase (car job)
+		(:shunt (destructuring-bind (tag new file) job
+			  (declare (ignore tag))
+			  (push `(:rmtmp ,new) revert)
+			  (if (probe-file file)
+			      (let ((old (safe-copy file "old")))
+				(push `(:rmtmp ,old) cleanup)
+				(push `(:revert ,old ,file) revert))
+			      (push `(:rmtmp ,file) revert))
+			  (rename new file)))
+		(:delete (destructuring-bind (tag file) job
+			   (declare (ignore tag))
+			   (let ((old (safe-copy file "delete")))
+			     (push `(:revert ,old ,file) revert)
+			     (push `(:rmtmp ,old) cleanup)
+			     (delete-file file)))))))
 	  (setf revert nil))
       (safely-unwind trail)
       (safely-unwind revert)
       (safely-unwind cleanup)
       (safely-reset safe))))
 
+;; The symbol `safely' is already exported.
 (defmacro safely ((safe &key) &body body)
   "Do stuff within the BODY safely.  If BODY completes without errors, the
    SAFE is committed; otherwise it's bailed."
@@ -245,6 +271,7 @@
        (when ,safe
 	 (safely-bail ,safe)))))
 
+(export 'safely-writing)
 (defmacro safely-writing ((stream file &rest open-args) &body body)
   "Simple macro for writing a single file safely.  STREAM is opened onto a
    temporary file, and if BODY completes, it is renamed to FILE."