safely.lisp: SAFE-COPY shouldn't make two copies under CLisp.

[lisp] / safely.lisp

diff --git a/safely.lisp b/safely.lisp
index 4830a99..9b4ab45 100644 (file)
--- a/safely.lisp
+++ b/safely.lisp
@@ -110,6 +110,13 @@
          (safely-trail safe))
     stream))
 
+(declaim (inline rename))
+(defun rename (old new)
+  (let ((target (make-pathname :directory '(:relative)
+                              :defaults new)))
+    #-clisp (rename-file old target)
+    #+clisp (rename-file old target :if-exists :overwrite)))
+
 (defun delete-file-without-moaning (file)
   "Delete the FILE, ignoring errors."
   (handler-case (delete-file file)
@@ -118,7 +125,7 @@
 (defun rename-file-without-moaning (old new)
   "Rename OLD to NEW, ignoring errors, and without doing any stupid name
    mangling."
-  (handler-case (rename-file old new)
+  (handler-case (rename old new)
     (file-error () nil)))
 
 (defun safely-unwind (trail)
@@ -166,7 +173,15 @@
                                (and from to
                                     (unix-link from to)))))
 
-  #-(or cmu sbcl)
+  #+clisp
+  (generate-fresh-file-name file tag
+                           (lambda (name)
+                             (posix:copy-file (namestring file)
+                                              (namestring name)
+                                              :method :hardlink
+                                              :if-exists nil)))
+
+  #-(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
@@ -205,23 +220,23 @@
          (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-file 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)