I am trying to get some information about a compiled GL shader program, in particular I need to get information about the Uniform Variables used.

The code I use is this:

  glGetProgramiv (program, GL_ACTIVE_UNIFORMS, &n_uniforms);
  fprintf (stderr, "%d uniforms:\n", n_uniforms);

  for (i = 0; i < n_uniforms; i++)
    {
      glGetActiveUniformName (program, i, 79, &namelen, name);
      name[namelen] = '\0';
      fprintf (stderr, "  %2d: %s\n", i, name);
    }

I get a segfault within glGetActiveUniformName, something is wrong here. The same code works fine with the NVidia proprietary drivers.

Some more information:

GL_VERSION   : 2.1 Mesa 10.3.2
GL_VENDOR    : Intel Open Source Technology Center
GL_RENDERER  : Mesa DRI Intel(R) Ironlake Mobile 
GLEW_VERSION : 1.10.0
GLSL VERSION : 1.20

This is using debian unstable with libgl1-mesa-glx:amd64, 10.3.2-1, amd64

Valgrind is not really helpful, even with debug symbols installed:

==27042== Process terminating with default action of signal 11 (SIGSEGV)
==27042==  Bad permissions for mapped region at address 0x0
==27042==    at 0x0: ???
==27042==    by 0x402BFF: main (shadertoy.c:458)
==27042==