I am still testing which setup gives me reliable shared D libraries which can be used from C.

Here is my latest test:

* test.d:
import std.stdio;
extern (C) {
  void hiD() {
    writeln("hi from D lib");
  }
}

* main.c
#include <stdio.h>
#include <dlfcn.h>
#include <stdlib.h>
void main() {
    void (*hiD)(void);
    void* handle = dlopen("./libtest.so", RTLD_LAZY);
    if (handle == NULL) {
        printf("%s\n", dlerror());
        exit(1);
    }	
    hiD = dlsym(handle, "hiD");
    if (hiD != NULL) {
        hiD();
    } else {
        printf("hiD is null\n");
    }
    dlclose(handle);
}

* Makefile
#!/bin/bash
test:
	#gdc-4.6 -g -c test.d -fPIC -o test.o
	#gdc-4.6 -shared -o libtest.so -fPIC test.o -lc -nostartfiles
	dmd -g -c test.d -fPIC
	ld -shared -o libtest.so test.o -lrt -lphobos2 -lpthread
	gcc -g main.c -ldl -lpthread
	./a.out
clean:
	rm -rf *.so *.o *.out

With this setup I get

  ./libtest.so: undefined symbol: _deh_beg

With a fake main method added I get

  make: *** [test] Segmentation fault

This is what I get from gdb

  Program received signal SIGSEGV, Segmentation fault.
  0xb7fd1ed3 in std.stdio.__T7writelnTAyaZ.writeln() (_param_0=...) at   /usr/include/d/dmd/phobos/std/stdio.d:1550
  1550	    enforce(fprintf(.stdout.p.handle, "%.*s\n",

Event with the following startup hooks

extern(C) {

  void gc_init();
  void gc_term();

  void _init() {
    gc_init();
  }

  void _fini() {
    gc_term();
  }

}

I get the same error. I am using dmd 2.058 on Ubuntu 11.10 (32 bit)

With gdc I get different errors, but it seems even more difficult to get it working.

Does anyone know what is missing to get proper shared library support working on Linux?

On 2012-04-08 10:45, "Timo Westkämper" <timo.westkamper@gmail.com>" wrote:
> I am still testing which setup gives me reliable shared D libraries
> which can be used from C.
>
> Here is my latest test:
>
> * test.d:
> import std.stdio;
> extern (C) {
> void hiD() {
> writeln("hi from D lib");
> }
> }
>
> * main.c
> #include <stdio.h>
> #include <dlfcn.h>
> #include <stdlib.h>
> void main() {
> void (*hiD)(void);
> void* handle = dlopen("./libtest.so", RTLD_LAZY);
> if (handle == NULL) {
> printf("%s\n", dlerror());
> exit(1);
> }
> hiD = dlsym(handle, "hiD");
> if (hiD != NULL) {
> hiD();
> } else {
> printf("hiD is null\n");
> }
> dlclose(handle);
> }
>
> * Makefile
> #!/bin/bash
> test:
> #gdc-4.6 -g -c test.d -fPIC -o test.o
> #gdc-4.6 -shared -o libtest.so -fPIC test.o -lc -nostartfiles
> dmd -g -c test.d -fPIC
> ld -shared -o libtest.so test.o -lrt -lphobos2 -lpthread
> gcc -g main.c -ldl -lpthread
> ./a.out
> clean:
> rm -rf *.so *.o *.out
>
> With this setup I get
>
> ./libtest.so: undefined symbol: _deh_beg
>
> With a fake main method added I get
>
> make: *** [test] Segmentation fault
>
> This is what I get from gdb
>
> Program received signal SIGSEGV, Segmentation fault.
> 0xb7fd1ed3 in std.stdio.__T7writelnTAyaZ.writeln() (_param_0=...) at
> /usr/include/d/dmd/phobos/std/stdio.d:1550
> 1550 enforce(fprintf(.stdout.p.handle, "%.*s\n",
>
> Event with the following startup hooks
>
> extern(C) {
>
> void gc_init();
> void gc_term();
>
> void _init() {
> gc_init();
> }
>
> void _fini() {
> gc_term();
> }
>
> }
>
> I get the same error. I am using dmd 2.058 on Ubuntu 11.10 (32 bit)
>
> With gdc I get different errors, but it seems even more difficult to get
> it working.
>
> Does anyone know what is missing to get proper shared library support
> working on Linux?

This is what I can think of for now:

* Proper initialization of TLS data
* Setting up exception handling tables
* Setting up module info

-- 
/Jacob Carlborg

On 04/08/2012 03:45 AM, "Timo Westkämper" <timo.westkamper@gmail.com>" wrote:
>
> extern(C) {
>
> void gc_init();
> void gc_term();
>
> void _init() {
> gc_init();
> }
>
> void _fini() {
> gc_term();
> }
>
> }

I think you want rt_init and rt_term here.

I'm interessting in the same stuff. I've a question to _tlsend and _tlsstart. What are they used for? My disputable presumption was that they point to the begin of TLS segment.


What is _deh_begin and _deh_end used for?

On Sunday, 8 April 2012 at 14:52:55 UTC, Ellery Newcomer wrote:
> On 04/08/2012 03:45 AM, "Timo Westkämper" <timo.westkamper@gmail.com>" wrote:
>>
>> extern(C) {
>>
>> void gc_init();
>> void gc_term();
>>
>> void _init() {
>> gc_init();
>> }
>>
>> void _fini() {
>> gc_term();
>> }
>>
>> }
>
> I think you want rt_init and rt_term here.

I got now the simple example working:

* Makefile:
#!/bin/bash
test:
	dmd -lib -g -c test.d -fPIC
	ld -shared -o libtest.so test.a -lrt -lphobos2 -lpthread
	gcc -g main.c -ldl -lpthread
	./a.out
clean:
	rm -rf *.a *.so *.o *.out

* test.d:
import std.stdio;
extern (C) void hiD() {
  writeln("hi from D lib");
}

Compiling as lib did the track and added the missing parts.

I will now advance with more complex examples.

On 2012-04-08 17:53, mta`chrono wrote:
> I'm interessting in the same stuff. I've a question to _tlsend and
> _tlsstart. What are they used for? My disputable presumption was that
> they point to the begin of TLS segment.

Yes, exactly, the start and end of the TLS segment.

> What is _deh_begin and _deh_end used for?

That would be start and end of the segment containing the exception handling tables.

-- 
/Jacob Carlborg

Does someone know why the lib (.a) packaging instead of objects (.o) works better in this case?

On Sunday, 8 April 2012 at 17:59:28 UTC, Timo Westkämper wrote:
> Does someone know why the lib (.a) packaging instead of objects (.o) works better in this case?

Didn't work after all with -lib. I mixed up outputs.

Well, if you're really hankering for a shared lib, try ldc. I have gotten it to compile working shared libs in the past.

On 04/09/2012 01:24 AM, "Timo Westkämper" <timo.westkamper@gmail.com>" wrote:
> On Sunday, 8 April 2012 at 17:59:28 UTC, Timo Westkämper wrote:
>> Does someone know why the lib (.a) packaging instead of objects (.o)
>> works better in this case?
>
> Didn't work after all with -lib. I mixed up outputs.

On Monday, 9 April 2012 at 15:14:45 UTC, Ellery Newcomer wrote:
> Well, if you're really hankering for a shared lib, try ldc. I have gotten it to compile working shared libs in the past.
>
> On 04/09/2012 01:24 AM, "Timo Westkämper" <timo.westkamper@gmail.com>" wrote:
>> On Sunday, 8 April 2012 at 17:59:28 UTC, Timo Westkämper wrote:
>>> Does someone know why the lib (.a) packaging instead of objects (.o)
>>> works better in this case?
>>
>> Didn't work after all with -lib. I mixed up outputs.

Thanks, I might switch to ldc, if dmd and gdc fail here.

I found this tls.S script in the druntime sources (src/rt/tls.S). Do you think it could be included in the library to make tls initialization work?

#if linux

/* The memory between the addresses of _tlsstart and _tlsend is the storage for
 * thread-local data in D 2.0.  Both of these rely on the default linker script
 * of:
 *      .tdata : { *(.tdata .tdata.* .gnu.linkonce.td.*) }
 *      .tbss  : { *(.tbss .tbss.* .gnu.linkonce.tb.*) *(.tcommon) }
 * to group the sections in that order.
 *
 * Sadly, this does not work because ld orders .tdata after .tdata.*, despite
 * what the linker script says.
 */

.file "tls.S"

.globl _tlsstart
    .section .tdata,"awT",@progbits
    .align 4
    .type   _tlsstart, @object
    .size   _tlsstart, 4
_tlsstart:
    .long   3

.globl _tlsend
    .section .tcommon,"awT",@nobits
    .align 4
    .type   _tlsend, @object
    .size   _tlsend, 4
_tlsend:
    .zero   4

#endif


I will see if I can copy the exception handling parts from the D main wrapping code.

As a temporary solution I did this

extern(C) void _deh_beg() { }
extern(C) void _deh_end() { }