Re: Race-condition ? (was: "Preserve owner and group" on MSDOS/Windows)

[Richard M. Stallman]

How about this fix?

*** fileio.c    24 Jun 2005 15:43:20 -0400      1.547
--- fileio.c    25 Jun 2005 16:56:28 -0400      
***************
*** 2406,2412 ****
    return;
  }
  
! DEFUN ("copy-file", Fcopy_file, Scopy_file, 2, 5,
         "fCopy file: \nGCopy %s to file: \np\nP",
         doc: /* Copy FILE to NEWNAME.  Both args must be strings.
  If NEWNAME names a directory, copy FILE there.
--- 2406,2412 ----
    return;
  }
  
! DEFUN ("copy-file", Fcopy_file, Scopy_file, 2, 6,
         "fCopy file: \nGCopy %s to file: \np\nP",
         doc: /* Copy FILE to NEWNAME.  Both args must be strings.
  If NEWNAME names a directory, copy FILE there.
***************
*** 2426,2434 ****
  that means to get an error if the file already exists; never overwrite.
  If MUSTBENEW is neither nil nor `excl', that means ask for
  confirmation before overwriting, but do go ahead and overwrite the file
! if the user confirms.  */)
!   (file, newname, ok_if_already_exists, keep_time, mustbenew)
       Lisp_Object file, newname, ok_if_already_exists, keep_time, mustbenew;
  {
    int ifd, ofd, n;
    char buf[16 * 1024];
--- 2426,2438 ----
  that means to get an error if the file already exists; never overwrite.
  If MUSTBENEW is neither nil nor `excl', that means ask for
  confirmation before overwriting, but do go ahead and overwrite the file
! if the user confirms.
! 
! If PRESERVE-UID-GID is non-nil, we try to transfer the
! uid and gid of FILE to NEWNAME.  */)
!   (file, newname, ok_if_already_exists, keep_time, mustbenew, 
preserve_uid_gid)
       Lisp_Object file, newname, ok_if_already_exists, keep_time, mustbenew;
+      Lisp_Object preserve_uid_gid;
  {
    int ifd, ofd, n;
    char buf[16 * 1024];
***************
*** 2570,2575 ****
--- 2574,2599 ----
        report_file_error ("I/O error", Fcons (newname, Qnil));
    immediate_quit = 0;
  
+   /* Preserve the owner and group, if requested.  */
+   if (input_file_statable_p && ! NILP (preserve_uid_gid))
+     fchown (ofd, st.st_uid, st.st_gid);
+ 
+   if (input_file_statable_p)
+     {
+ #ifndef MSDOS
+       fchmod (ofd, st.st_mode & 07777);
+ #else /* MSDOS */
+ #if defined (__DJGPP__) && __DJGPP__ > 1
+       /* In DJGPP v2.0 and later, fstat usually returns true file mode bits,
+          and if it can't, it tells so.  Otherwise, under MSDOS we usually
+          get only the READ bit, which will make the copied file read-only,
+          so it's better not to chmod at all.  */
+       if ((_djstat_flags & _STFAIL_WRITEBIT) == 0)
+       chmod (SDATA (encoded_newname), st.st_mode & 07777);
+ #endif /* DJGPP version 2 or newer */
+ #endif /* MSDOS */
+     }
+ 
    /* Closing the output clobbers the file times on some systems.  */
    if (emacs_close (ofd) < 0)
      report_file_error ("I/O error", Fcons (newname, Qnil));
***************
*** 2587,2604 ****
                     Fcons (build_string ("Cannot set file date"),
                            Fcons (newname, Qnil)));
        }
- #ifndef MSDOS
-       chmod (SDATA (encoded_newname), st.st_mode & 07777);
- #else /* MSDOS */
- #if defined (__DJGPP__) && __DJGPP__ > 1
-       /* In DJGPP v2.0 and later, fstat usually returns true file mode bits,
-          and if it can't, it tells so.  Otherwise, under MSDOS we usually
-          get only the READ bit, which will make the copied file read-only,
-          so it's better not to chmod at all.  */
-       if ((_djstat_flags & _STFAIL_WRITEBIT) == 0)
-       chmod (SDATA (encoded_newname), st.st_mode & 07777);
- #endif /* DJGPP version 2 or newer */
- #endif /* MSDOS */
      }
  
    emacs_close (ifd);
--- 2611,2616 ----
***************
*** 2775,2781 ****
      {
        if (errno == EXDEV)
        {
-         struct stat data;
  #ifdef S_IFLNK
            symlink_target = Ffile_symlink_p (file);
            if (! NILP (symlink_target))
--- 2787,2792 ----
***************
*** 2783,2797 ****
                                   NILP (ok_if_already_exists) ? Qnil : Qt);
            else
  #endif
!             Fcopy_file (file, newname,
!                         /* We have already prompted if it was an integer,
!                            so don't have copy-file prompt again.  */
!                         NILP (ok_if_already_exists) ? Qnil : Qt,
!                       Qt, Qnil);
! 
!         /* Preserve owner and group, if possible (if we are root).  */
!         if (stat (SDATA (encoded_file), &data) >= 0)
!           chown (SDATA (encoded_file), data.st_uid, data.st_gid);
  
          Fdelete_file (file);
        }
--- 2794,2804 ----
                                   NILP (ok_if_already_exists) ? Qnil : Qt);
            else
  #endif
!           Fcopy_file (file, newname,
!                       /* We have already prompted if it was an integer,
!                          so don't have copy-file prompt again.  */
!                       NILP (ok_if_already_exists) ? Qnil : Qt,
!                       Qt, Qnil, Qt);
  
          Fdelete_file (file);
        }