.note.tag, readelf and dsynth version detection

[Romick]

I was probably lucky :) Of course, I could be wrong, but it seems to me
that these pieces are not "fields" of the same structure, these are fields
that belong to two records in the file. Is the order of these records
guaranteed?

I mean, it’s possible if I rebuild the world now, the linker will arrange
these records in a different order and everything will be fine, or maybe
not :)

On Mon, Jan 27, 2020 at 03:56:25PM -0800, Matthew Dillon wrote:
> That's ... weird.  the 'zero' and the 'version' fields are transposed.  Are you
> compiling in any special way?   I've tested -release and -master on a bunch of
> boxes and they all have the version in the right spot.
> 
> -Matt
> 
> On Mon, Jan 27, 2020 at 1:45 PM Romick <yellowrabbit2010 at gmail.com> wrote:
> 
>     Hello,
>     It seems that dsynth defines the system version based on the .note.tag(s)
>     in
>     /bin/sh and a necessary condition is that these entries follow in a
>     certain order.  On my system this is not so :)
> 
>     ==========
>     rabbit at fly ~% readelf -x .note.tag /bin/sh
> 
>     Hex dump of section '.note.tag':
>       0x00400218 0a000000 04000000 20000000 44726167 ........ ...Drag
>       0x00400228 6f6e466c 79000000 00000000 0a000000 onFly...........
>       0x00400238 04000000 01000000 44726167 6f6e466c ........DragonFl
>       0x00400248 79000000 e5a30700                   y.......
> 
>     rabbit at fly ~%
>     ==========
> 
>     === /usr/src/usr.bin/dsynth/config.c ===
>     struct NoteTag {
>             Elf_Note note;
>             char osname1[12];
>             int version;            /* e.g. 500702 -> 5.7 */
>             int x1;
>             int x2;
>             int x3;
>             char osname2[12];
>             int zero;
>     };
>     ========================================
> 
>     --
>       with best regards,   
>       Yellow Rabbit @yrabbit at mastodon.sdf.org
>       DragonFly 5.7-DEVELOPMENT x86_64
> 

-- 
  with best regards,    
  Yellow Rabbit @yrabbit at mastodon.sdf.org
  DragonFly 5.7-DEVELOPMENT x86_64
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