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digitalmars.D.learn - Why does object creation give segmentation fault in DLL?

reply "Tolga Cakiroglu" <tcak pcak.com> writes:
I have written a DLL file in Linux (x86_64). It is as below:

File: lib.dll
=====================
class A{}

extern(C) void foo(){
	Object obj = new Object();   // test 1

	A objA = new A();  // test 2

	char[] c = new char[ 1024 ];   // test 3
}


Compilation code is below:
	dmd -c lib.d -fPIC -debug
	gcc --shared lib.o -o lib.so


Output of programme is like that:
library is loaded now
foo() function is found
unloading libdll.so
Segmentation fault (core dumped)


Situation is that if either only the `test 1` or `test 3` code is 
available in the function, there is no error at all. But once I 
use `test 2` code, it starts giving segmentation fault. Please 
notice that both `test 1` and `test 2` are creating an object 
already. And all of them allocates memory with `new` keyword. But 
only the `test 2` fails. Why is this happening?
Feb 22 2014
parent reply "evilrat" <evilrat666 gmail.com> writes:
On Saturday, 22 February 2014 at 09:09:42 UTC, Tolga Cakiroglu 
wrote:

 I have written a DLL file in Linux (x86_64). It is as below:

 File: lib.dll
 =====================
 class A{}

 extern(C) void foo(){
 	Object obj = new Object();   // test 1

 	A objA = new A();  // test 2

 	char[] c = new char[ 1024 ];   // test 3
 }


 Compilation code is below:
 	dmd -c lib.d -fPIC -debug
 	gcc --shared lib.o -o lib.so


 Output of programme is like that:
 library is loaded now
 foo() function is found
 unloading libdll.so
 Segmentation fault (core dumped)


 Situation is that if either only the `test 1` or `test 3` code 
 is available in the function, there is no error at all. But 
 once I use `test 2` code, it starts giving segmentation fault. 
 Please notice that both `test 1` and `test 2` are creating an 
 object already. And all of them allocates memory with `new` 
 keyword. But only the `test 2` fails. Why is this happening?


you should init runtime in library and set gc proxy for it(if 
implemented on linux, otherwise you would have two gc's running 
simultaneously)

so add following methods to your lib.


// lib side
void initRT()
{
import core.runtime();
Runtime.initilize();
}

extern(C) void  gc_setProxy(void* p);
void setGCProxy(void* gc)
{
gc_setProxy(gc);
}

// executable side

extern(C) void* gc_getProxy();

void main()
{
// load lib here
initRT();
setGCProxy(gc_getProxy());
// do stuff here...
}
Feb 22 2014
parent "Tolga Cakiroglu" <tcak pcak.com> writes:
On Saturday, 22 February 2014 at 11:08:41 UTC, evilrat wrote:

 On Saturday, 22 February 2014 at 09:09:42 UTC, Tolga Cakiroglu 
 wrote:

 I have written a DLL file in Linux (x86_64). It is as below:

 File: lib.dll
 =====================
 class A{}

 extern(C) void foo(){
 	Object obj = new Object();   // test 1

 	A objA = new A();  // test 2

 	char[] c = new char[ 1024 ];   // test 3
 }


 Compilation code is below:
 	dmd -c lib.d -fPIC -debug
 	gcc --shared lib.o -o lib.so


 Output of programme is like that:
 library is loaded now
 foo() function is found
 unloading libdll.so
 Segmentation fault (core dumped)


 Situation is that if either only the `test 1` or `test 3` code 
 is available in the function, there is no error at all. But 
 once I use `test 2` code, it starts giving segmentation fault. 
 Please notice that both `test 1` and `test 2` are creating an 
 object already. And all of them allocates memory with `new` 
 keyword. But only the `test 2` fails. Why is this happening?


 you should init runtime in library and set gc proxy for it(if 
 implemented on linux, otherwise you would have two gc's running 
 simultaneously)

 so add following methods to your lib.


 // lib side
 void initRT()
 {
 import core.runtime();
 Runtime.initilize();
 }

 extern(C) void  gc_setProxy(void* p);
 void setGCProxy(void* gc)
 {
 gc_setProxy(gc);
 }

 // executable side

 extern(C) void* gc_getProxy();

 void main()
 {
 // load lib here
 initRT();
 setGCProxy(gc_getProxy());
 // do stuff here...
 }


After doing these, even without `test 2` segmentation fault 
started coming. I actually do not want to share GC between them 
right now.
Feb 22 2014