[Libguestfs] Patchable build problems on OS X 10.10

[Richard W.M. Jones]

On Sat, Feb 07, 2015 at 02:51:53AM +0000, Margaret Lewicka wrote:
> On 6 February 2015 at 10:03, Richard W.M. Jones <rjones at redhat.com> wrote:
> [...]
> > Linux doesn't have getprogname.  One way around this is to add
> > getprogname to the list of functions in configure.ac AC_CHECK_FUNCS.
> > That will cause a macro to be defined which you can use like this:
> >
> >   #if HAVE_DECL_PROGRAM_INVOCATION_SHORT_NAME == 1
> >   #  define program_name program_invocation_short_name
> >   #elif HAVE_GETPROGNAME
> >   #  define program_name getprogname()
> >   #else
> >   #  define program_name "libguestfs"
> >   #endif
> 
> Unfortunately that still doesn't help the issue with gnulib, since it
> expects char *program_name to be set on non-Linux platforms.

I believe I understand the problem now.  The gnulib 'error' module
uses program_name.  As you say above on some platforms -- but not
Linux / glibc -- it references it as:

  extern char *program_name;

This means when you compile libguestfs on non-glibc (eg. Mac OS X)
gnulib requires program_name as an external reference, which we don't
provide.

Complicating this is that libguestfs defines a macro called
program_name, which prevents us from easily defining the required
external symbol.

Anyway, I have changed libguestfs to use the macro
guestfs___program_name which cannot conflict with anything:

  https://github.com/libguestfs/libguestfs/commit/5cafedaa45d5993c54bf1827426171d9e23d77ae

I'm not quite sure who/what gnulib is expecting to define
program_name.  While it would be possible to add the following to
libguestfs somewhere (in a .c file):

  #if /*compiling for Mac OS X*/
  char *program_name = "libguestfs";
  #endif

that could be a mistake if either Darwin itself or the main program
(not a library like libguestfs) is expected to define this symbol.  So
over to you to experiment!

Thanks,

Rich.

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