Dealing with version-specific syntax

[André Pönitz]

On Wednesday 12 January 2011 20:27:50 ext Anton Ertl wrote:
> What I am trying to do: Get the disassembly for a specific address
> range.  And I try to do it with gdb.  The problem here ist that as far
> as I can tell, up to gdb-7.0 the way to do this is
> 
> disassemble 0x404E22 0x404E40
> 
> Starting from gdb-7.1, this syntax is invalid, and instead we have to
> use
> 
> disassemble 0x404E22,0x404E40
> 
> Unfortunately, this syntax does something else in gdb-7.0 and earlier
> (it disassembles whole functions).
> 
> Is there a good way inside gdb for deciding which syntax to use?
> Ideally, I would test if the space-separated syntax works, and use it
> if it does, and otherwise use the comma-syntax.  Or I might test for
> the gdb version and use the syntax depending on that.

That's unfortunately not necessarily a safe approach as gdb version strings 
can be virtually anything. Some distributors get really creative there ;-}

> If there is no easy way, we will probably take the approach of testing
> the gdb version outside of gdb.

You could decide what syntax to use in the same session before loading
a file:

  disassemble 0 1

will produce either

  Dump of assembler code from 0x0 to 0x1:
  0x00000000:     Cannot access memory at address 0x0

or

   A syntax error in expression, near `1'.

Andre'