Re: ld/emultempl/elf32.em trusts inode numbers even under Mingwin

[Zack Weinberg <zack at codesourcery dot com>]

"Dave Korn" <dave.korn@artimi.com> writes:

>> > It looks to me that mingw sets the st_dev field to the index of the
>> > DOS drive letter (excluding any skipped devices, so on my PC, A=1,
>> > C=2, etc...) and sets the st_ino to zero.
>> 
>> Okay.  That's mostly consistent with my observations, though I was
>> working out of Y: and I don't know why st_dev was zero... but there's
>> plenty weird about my Windows test box, so it could just be me.
>
>   Yeh.  What kind of drive is your Y:?  SMB or NFS remote, perhaps?
> That might make a difference.  Anyway, it seems like testing inode
> == 0 should be effective.  Or just disable the optimisation
> altogether for mingw.  I don't think there's any straightforward,
> quick, efficient way to tell if two files are the same in the
> general case.

It was indeed NFS remote.  I agree, testing inode == 0 ought to be
adequate.  Here's a revised patch.

zw

        * emultempl/elf32.em (gld${EMULATION_NAME}_stat_needed):
        Do not indicate a duplicate if st_ino is zero.

===================================================================
Index: ld/emultempl/elf32.em
--- ld/emultempl/elf32.em	3 Feb 2005 14:12:54 -0000	1.127
+++ ld/emultempl/elf32.em	8 Feb 2005 20:14:58 -0000
@@ -231,8 +231,16 @@ gld${EMULATION_NAME}_stat_needed (lang_i
       return;
     }
 
+  /* Some operating systems, e.g. Windows, do not provide a meaningful
+     st_ino; they always set it to zero.  (Windows _does_ provide a
+     meaningful st_dev.)  Do not indicate a duplicate library in that
+     case.  While there is no guarantee that a system that provides
+     meaningful inode numbers will never set st_ino to zero, that
+     inode number is reserved by all Unix file systems in common use
+     (UFS, ext2, etc.) so we need not worry about that possibility.  */
   if (st.st_dev == global_stat.st_dev
-      && st.st_ino == global_stat.st_ino)
+      && st.st_ino == global_stat.st_ino
+      && st.st_ino != 0)
     {
       global_found = TRUE;
       return;