Re: HEADS-UP: Library version number bumps

On Wed, Sep 29, 2004 at 09:44:22AM -0700, Kris Kennaway wrote:
> 
> libncurses.so.5 in 5.x does not export many of the global variables
> exported by 4.x version of libncurses.so.5.  The missing symbols are:
> 
>     23: 0003e270     4 OBJECT  GLOBAL DEFAULT   12 SP
>    166: 0000ee58    26 FUNC    GLOBAL DEFAULT    9 _nc_tracebits
>    170: 00037c0e     2 OBJECT  GLOBAL DEFAULT   12 ospeed
>    175: 00037c2c     4 OBJECT  GLOBAL DEFAULT   12 TABSIZE
>    188: 00036870     4 OBJECT  GLOBAL DEFAULT   12 BC
>    247: 00037744     4 OBJECT  GLOBAL DEFAULT   12 COLOR_PAIRS
>    333: 00037c0c     1 OBJECT  GLOBAL DEFAULT   12 PC
>    370: 00037c1c     4 OBJECT  GLOBAL DEFAULT   12 cur_term
>    406: 00037540   512 OBJECT  GLOBAL DEFAULT   12 acs_map
>    434: 00037748     4 OBJECT  GLOBAL DEFAULT   12 COLORS
>    450: 0003e260     4 OBJECT  GLOBAL DEFAULT   12 stdscr
>    495: 00037c28     4 OBJECT  GLOBAL DEFAULT   12 COLS
>    498: 0003e268     4 OBJECT  GLOBAL DEFAULT   12 newscr
>    515: 0003e264     4 OBJECT  GLOBAL DEFAULT   12 curscr
>    528: 0003686c     4 OBJECT  GLOBAL DEFAULT   12 UP
>    545: 00037c24     4 OBJECT  GLOBAL DEFAULT   12 LINES

Something is going wrong with your script, since most of those are
well-defined symbols that are present in the normal and wide-character
libraries.  (None are functions, all are variables).

** If the script is blameless, then there's a change in the way the
** linker builds shared libraries (the point I was trying to establish).

The wide-character library uses a macro for acs_map (but then, we're not
talking about that ;-).

The only other one that is noticeable is the private _nc_tracebits
symbol (not the topic of this discussion, since applications that use
private symbols aren't supported by anyone that I recall).

> A 4.x binary that calls _nc_tracebits() will fail outright when run on
> 5.x, but this is a debugging function and not likely to be widely used
> in the real world, so that isn't a big deal.

_nc_tracebits is a variable, not a function.  You can't "call" it.

Also - checking the changelog - _nc_tracebits was not in ncurses 4.2
(it was introduced in late 1998).
 
> However, if a 4.x binary sets one of the other variables in the above
> list expecting it to have some effect on the library (or vice versa,
> i.e. expects to read the state of the library by accessing the
> globals), it will not behave the same way when run on 5.x.
> 
> If I'm mistaken about the implications (perhaps you can guarantee that
> the above will not happen), please let us know.
> 
> Kris



-- 
Thomas E. Dickey
http://invisible-island.net
ftp://invisible-island.net