Why I'm touchy about over-zealous API deprecation.

gistfile1.c

static S32 hasext( char const * which )
{
#ifdef TARGET_GL_CORE
  // GL Core deprecates glGetString(GL_EXTENSIONS)
  GLint i, num_exts;

  glGetIntegerv( GL_NUM_EXTENSIONS, &num_exts );
  for ( i = 0 ; i < num_exts ; i++ )
    if ( strcmp( which, (char const *) glGetStringi( GL_EXTENSIONS, i ) ) == 0 )
      return 1;

  return 0;
#else
  char const * exts = (char const *) glGetString( GL_EXTENSIONS );
  char const * where = strstr( exts, which );
  size_t len = strlen( which );

  if ( !where )
    return 0;

  return ( where == exts || *( where - 1 ) == ' ' ) && // starts with terminator
    ( where[ len ] == ' ' || where[ len ] == 0 ); // ends with terminator
#endif
}

static S32 Platform_Init()
{
#ifdef TARGET_GL_ES
  s_HasUnpackRowLength = hasext( "GL_EXT_unpack_subimage" );
#endif

  return 1;
}

static void update_texture_subrect( GLuint x0, GLuint y0, GLuint x1, GLuint y1, void const * buffer, GLsizei stride )
{
#ifdef GL_UNPACK_ROW_LENGTH
  if ( s_HasUnpackRowLength )
  {
    glPixelStorei( GL_UNPACK_ROW_LENGTH, stride );
    glTexSubImage2D( GL_TEXTURE_2D, 0, x0, y0, x1 - x0, y1 - y0, TEXFORMAT, GL_UNSIGNED_BYTE, (char *)buffer + y0*stride + x0 );
    glPixelStorei( GL_UNPACK_ROW_LENGTH, 0 );
  }
  else
#endif
  {
    // without unpack row length, have to upload strided textures line by line
    GLuint y;
    for ( y = y0 ; y < y1 ; y++ )
      glTexSubImage2D( GL_TEXTURE_2D, 0, x0, y, x1 - x0, 1, TEXFORMAT, GL_UNSIGNED_BYTE, (char *)Buffer + y*stride + x0 );
  }
}