From: Mark Wooding <mdw@distorted.org.uk>
Date: Sun, 17 Jul 2011 20:51:16 +0000 (+0100)
Subject: safely.lisp: More on the CLisp RENAME-FILE mess.
X-Git-Url: https://git.distorted.org.uk/~mdw/lisp/commitdiff_plain/9224720f63a3a3f810ce03dc4018e23a0c6d8492

safely.lisp: More on the CLisp RENAME-FILE mess.

The :IF-EXISTS option is only in very new versions of CLisp.  It turns
out that the bizarre double-pathname-merging bug in POSIX:COPY-FILE
doesn't cause trouble if the source is absolute (unsurprising, in
retrospect) so I could use TRUENAME to dig my way out of this mess; but
COPY-FILE will clobber the target file before looking to see whether the
source succeeds (unless persuaded otherwise with :IF-EXISTS, which only
works if RENAME-FILE understands that option).

Give up, and use rename(2) through the FFI.
---

diff --git a/safely.lisp b/safely.lisp
index 9b4ab45..0674429 100644
--- a/safely.lisp
+++ b/safely.lisp
@@ -110,12 +110,25 @@
 	  (safely-trail safe))
     stream))
 
+#+clisp
+(progn
+  (ffi:def-call-out %rename (:name "rename")
+    (:language :stdc)
+    (:arguments (from ffi:c-string)
+		(to ffi:c-string))
+    (:return-type ffi:int)))
+
 (declaim (inline rename))
 (defun rename (old new)
+  #-clisp
   (let ((target (make-pathname :directory '(:relative)
 			       :defaults new)))
-    #-clisp (rename-file old target)
-    #+clisp (rename-file old target :if-exists :overwrite)))
+    (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."