Re: Darwin Port

I did some browsing around the Mac documentation, and I came across 
some articles on Umbrella Frameworks, which is another way of saying 
"frameworks within frameworks." The nifty thing about these is that 
when the dynamic linker cannot find a symbol in the base framework, it 
looks in its child frameworks for the symbols.  This takes care of a 
lot of problems the dynamic linker has given me about certain symbols 
it expected to find in libGL.dylib (specifically gll_noop and 
gll_pkey).  In order to implement this, though, we have to create a 
temporary framework file structure.  The following is a list of the 
folders I used to test this out:

/private/tmp/OpenGL.framework
cwaters% ls -lR
  Frameworks -> Versions/Current/Frameworks
  Headers -> Versions/Current/Headers
  Libraries -> Versions/Current/Libraries
  OpenGL -> Versions/Current/OpenGL
  Resources -> Versions/Current/Resources
  Versions

./Versions:
  A
  Current -> A

./Versions/A:
  Frameworks
  Headers -> 
/System/Library/Frameworks/OpenGL.framework/Versions/A/Headers
  Libraries
  OpenGL -> /cr/lib/Darwin/libcrfaker.dylib
  Resources -> 
/System/Library/Frameworks/OpenGL.framework/Versions/A/Resources

./Versions/A/Frameworks:
  NOpenGL.framework -> /System/Library/Frameworks/OpenGL.framework

./Versions/A/Libraries:
  libGL.dylib -> /cr/lib/Darwin/libcrfaker.dylib

After I made all the folders and symbolic links, I preappeneded "/tmp" 
to DYLD_FRAMEWORK_PATH (in app_faker.c)
I wouldn't say it worked sucessfully, since the program itself crashed 
after creating/setting the context, but I would say that it -worked-, 
in the sense that the faker's CGL functions were actually called.

Attached is a diff between the HEAD app_faker.c and the app_faker.c 
with the implementation I wrote for this purpose.

  -Chris Waters



On Jun 23, 2004, at 2:11 PM, Christopher Waters wrote:

> Attached is the "change log" I made.  The tarballed code can be found 
> at: http://www.cse.msstate.edu/~crw7/vis/cr-1.1.tar.gz
> I restarted off of HEAD yesterday morning, so it should be up to date.
>
> I got most of my ideas for all of this (using AGL in spus and CGL in 
> faker; defining SPU before including arch.mk; etc) from Jorge's 
> "Darwin Patch" mails.
> Everything builds fine, but then goes downhill when trying to run the 
> app faker :(
>
> There seems to be some trick in "tricking" the dynamic linker, too... 
> forcing a flat namspace and then inserting the faker library only 
> worked until you tried to call functions in the actual opengl library.
>
>  -Chris Waters
>
> <Darwin_work.rtf>

55a56,57
> #elif defined(DARWIN)
> #define OPENGL_CLIENT_LIB "libcrfaker.dylib"
65a68,69
> #elif defined(DARWIN)
> #define SYSTEM_LIB_DIR "/System/Libraries/Frameworks/OpenGL.framework/Libraries"
72a77,78
> #elif defined(DARWIN)
> 	"libGL.dylib"
485a492,543
> #ifdef DARWIN
> #define TEMP_FRAMEWORK_NAME "OpenGL.framework"
> #define SYSTEM_GL_PATH		"/System/Library/Frameworks/OpenGL.framework"
> 
> #define MAKEADD_DIR(n)  ( mkdir((n),0777), add_dir_to_temp_list((n)) )
> 
> static void make_temp_framework( const char *dir ) {
> 	char name[1024];
> 
> 	(void) libgl_names;
> 
> 	crStrcpy( name, dir );
> 	crStrcat( name, "/" TEMP_FRAMEWORK_NAME );
> 	MAKEADD_DIR( name );
> 
> 	crStrcat( name, "/Versions" );
> 	MAKEADD_DIR( name );
> 
> 	crStrcat( name, "/A" );
> 	MAKEADD_DIR( name );
> 
> 	make_temp_link( name, "Current", "A" );
> 
> 	crStrcat( name, "/Frameworks" );
> 	MAKEADD_DIR( name );
> 
> 	crStrcpy( name, dir );
> 	crStrcat( name, "/" TEMP_FRAMEWORK_NAME "/Versions/A/Libraries" );
> 	MAKEADD_DIR( name );
> 
> 	crStrcpy( name, dir );
> 	crStrcat( name, "/" TEMP_FRAMEWORK_NAME );
> 
> 	make_temp_link( name, "Frameworks", "Versions/Current/Frameworks" );
> 	make_temp_link( name, "Headers", "Versions/Current/Headers" );
> 	make_temp_link( name, "Libraries", "Versions/Current/Libraries" );
> 	make_temp_link( name, "OpenGL", "Versions/Current/OpenGL" );
> 	make_temp_link( name, "Resources", "Versions/Current/Resources" );
> 
> 	crStrcat( name, "/Versions/A" );
> 	make_temp_link( name, "Headers", SYSTEM_GL_PATH "/Headers" );
> 	make_temp_link( name, "OpenGL", cr_lib );
> 	make_temp_link( name, "Resources", SYSTEM_GL_PATH "/Resources" );
> 
> 	/* these are the most important parts */
> 	make_temp_link( name, "Frameworks/NOpenGL.framework", SYSTEM_GL_PATH );
> 
> 	crStrcat( name, "/Libraries" );
> 	make_temp_link( name, "libGL.dylib", cr_lib );
> }
> #endif
> 
545a604,606
> #ifdef DARWIN
> 	make_temp_framework( tmpdir );
> #else
566a628
> #endif
569a632,633
> #elif defined(DARWIN)
> 	prefix_env_var( tmpdir, "DYLD_FRAMEWORK_PATH" );