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

[lisp] / safely.lisp

diff --git a/safely.lisp b/safely.lisp
index 0a05f8b..9b4ab45 100644 (file)
--- a/safely.lisp
+++ b/safely.lisp
@@ -30,6 +30,17 @@
           #:safely-writing))
 (in-package #:safely)
 
+#+(or cmu sbcl)
+(eval-when (:compile-toplevel :execute)
+  (import #+cmu '(ext:unix-namestring unix:unix-link)
+         #+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))
   "Stores information about how to commit or undo safe writes."
   (streams nil)
@@ -99,6 +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)
@@ -107,7 +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)
@@ -136,19 +154,34 @@
   (safely-unwind (safely-trail safe))
   (safely-reset safe))
 
+#+sbcl
+(defun unix-link (from to)
+  (sb-unix::int-syscall ("link" sb-alien:c-string sb-alien:c-string)
+                       from to))
+
 (defun safe-copy (file tag)
   "Make a copy of the FILE.  Return the new name."
 
-  #+cmu
+  #+(or cmu sbcl)
   ;; Use link(2) where available.
   (generate-fresh-file-name file tag
                            (lambda (name)
-                             (let ((from (ext:unix-namestring file t))
-                                   (to (ext:unix-namestring name nil)))
+                             (let ((from (native-namestring file
+                                                            :as-file t))
+                                   (to (native-namestring name
+                                                          :as-file t)))
                                (and from to
-                                    (unix:unix-link from to)))))
+                                    (unix-link from to)))))
+
+  #+clisp
+  (generate-fresh-file-name file tag
+                           (lambda (name)
+                             (posix:copy-file (namestring file)
+                                              (namestring name)
+                                              :method :hardlink
+                                              :if-exists nil)))
 
-  #-cmu
+  #-(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
@@ -187,23 +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)
@@ -227,8 +260,7 @@
    temporary file, and if BODY completes, it is renamed to FILE."
   (with-gensyms safe
     `(safely (,safe)
-       (let ((,stream (apply #'safely-open-output-stream
-                            ,safe ,file ,open-args)))
+       (let ((,stream (safely-open-output-stream ,safe ,file ,@open-args)))
         ,@body))))
 
 ;;;----- That's all, folks --------------------------------------------------