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how to create ".dylib"s for Mac OS X?

BlitzMax Forums/BlitzMax Programming/how to create ".dylib"s for Mac OS X?

Rozek(Posted 2008) [#1]
Good morning!

I'll soon have to decide whether to use BlitzMAX or PureBasic for my developments. The most important aspect will be whether I will be able to produce dynamically loadable libraries for all supported platforms (i.e., DLLs, DyLibs, Shared Objects)

I would really prefer to use BlitzMAX, but

- I managed to build and use a DLL under Windows (XP)
- when I try the same under Mac OS X, the application crashes
- I have not yet tried the same under Linux (as Mac OS X is more important)

Has anybody managed to build DyLibs and Shared Objects?

Here is my approach for Mac OS X:

- the library (DLLTest_DLL.bmx):

strict

framework brl.blitz


function DoubleIt:int (Value:int)
' GCEnter()
  return 2*Value
end function


- the definition file (DLLTest_DLL.def, bmk did not complain - it might therefore be correct)

EXPORTS

DoubleIt=bb_DoubleIt


- the command to build the library

/Applications/BlitzMax/bin/bmk makelib DLLTest_DLL.bmx


- the test program (DLLTest.bmx)

Strict

Framework brl.blitz

Extern "C"  ' see /usr/include/dlfcn.h, POSIX part only
  function dlclose:byte ptr (Handle:byte ptr)
  function dlerror$z        ()
  function  dlopen:byte ptr (Path$z, Mode:int)
  function   dlsym:byte ptr (Handle:byte ptr, Symbol$z)
End Extern


Const RTLD_LAZY         = $01 ' lazy function call binding
Const RTLD_NOW          = $02 ' immediate function call binding
Const RTLD_LOCAL        = $04
Const RTLD_GLOBAL       = $08



Local Library:Byte Ptr = dlopen("DLLTest_DLL", RTLD_GLOBAL | RTLD_NOW)
If (Not Library) Then
  WriteStdout "Library could not be loaded~n"
  Throw "library not found"
Else
  WriteStdout "Library loaded~n"
End If

WriteStdout "dlerror() = " + dlerror() + "~n"


Local DoubleIt:Int (Value:Int)
DoubleIt = dlsym(Library,"DoubleIt")
If (Not DoubleIt) Then
  WriteStdout "unable to obtain symbol 'DoubleIt'~n"
End If

WriteStdout "DoubleIt(10) = " + DoubleIt(10)
WriteStdout "Yippee!~n"

dlclose(Library)


This test is a modification of what I found in this forum and by looking into the file "/usr/include/dlfcn.h"

If I start the test, the application crashes and I get the following dump



Does anybody have a clue what is going wrong here?

Thanks in advance for any help!


Rozek(Posted 2008) [#2]
There is another strange problem:

somebody in this forum mentioned the use of "GCEnter()" whithin the DLL functions in order to let the built-in garbage collector run properly.

Under Win32, I am able to build a DLL which calls this function - under Mac OS X, I am not. Here is the linker error message:



Does anybody have an idea why?


MacSven(Posted 2008) [#3]
Use dll‘s on MacOS X????? Is this possible!!!!!!!


GaryV(Posted 2008) [#4]
Use dll‘s on MacOS X????? Is this possible!!!!!!!
No.


plash(Posted 2008) [#5]
@MacSven: No, but using the equivalent (a MacOS shared library - a .dylib) is possible.


Brucey(Posted 2008) [#6]
Has anybody managed to build DyLibs and Shared Objects?

I've tried to build a screensaver framework... no joy - doesn't like the non-relocatable assembler which BlitzMax creates. (well, that's what the error complains about).

It's possible that a dynamic library *may* work, but I have not tried it yet - no need.


plash(Posted 2008) [#7]
It's possible that a dynamic library *may* work, but I have not tried it yet - no need.
Ah, so a dylib and a shared object/library are two different things..


Rozek(Posted 2008) [#8]
Hello!

Thanks for all your answers.

I've (almost immediately) managed to produce a .dylib using the free XCode development system - but I will have to code in C (or C++) then, which I would like to avoid.

But, since PureBasic is currently unable to build .dylibs as well, it seems as if I would have to continue with C.

Is there any chance that BlitzMAX could "learn" how to produce .dylibs? (compiler/assembler flag, injecting an intermediate (C/C++) code into XCode, or some other weird but automatable solution?)

Thanks in advance for any answers.


ImaginaryHuman(Posted 2008) [#9]
Brucey, you tried screensavers that support blitzmax code on the mac? How did that go in general? I tried it too but all that objective c framework stuff is not my forte.


Rozek(Posted 2009) [#10]
Hello!

I just tested BlitzMax 1.33rc5 - with the same results as before... :-(

Actually, this means that it is impossible to produce .dylibs for MacOS X with BlitzMax


ImaginaryHuman(Posted 2009) [#11]
If it's impossible then why would the feature be in there?


Rozek(Posted 2010) [#12]
Hello again (after quite a while)

I just tried to use the current version of BlitzMAX (i.e. 1.37) to create and load a .dylib - and failed again!

Using the approach mentioned above

- the DLLTest is able to load the ".dylib" (it claims so, at least) but never finds the exported symbol
- the DLLTest crashes on the invokation of "dlclose"

Has anybody else found a way to create DLLs/DyLibs/SOs? (i.e. dynamically loadable libraries an any supported platform)