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digitalmars.D.learn - The module 'foo' is already defined in 'libmylib.so'

reply Timothee Cour via Digitalmars-d-learn <digitalmars-d-learn puremagic.com> writes:
I want to update a library with new symbols (ie partial recompilation):

libmylib.so : compiled from bar.d and foo.d

now update the file foo.d

dmd -c -fPIC foo.d -offoo.o

clang++ -o libmylib_update.so foo.o -shared -Wl,-lmylib

When trying to dlopen libmylib_update.so from C++ it fails with:
The module 'foo' is already defined in 'libmylib.so'

(it somehow works when the dlopen is called from D)

How would I achieve that?
Dec 01 2016
parent reply Nicholas Wilson <iamthewilsonator hotmail.com> writes:
On Thursday, 1 December 2016 at 22:05:06 UTC, Timothee Cour wrote:

 I want to update a library with new symbols (ie partial 
 recompilation):

 libmylib.so : compiled from bar.d and foo.d

 now update the file foo.d

 dmd -c -fPIC foo.d -offoo.o

 clang++ -o libmylib_update.so foo.o -shared -Wl,-lmylib

 When trying to dlopen libmylib_update.so from C++ it fails 
 with: The module 'foo' is already defined in 'libmylib.so'

 (it somehow works when the dlopen is called from D)

 How would I achieve that?


Have a look at what `trace -E d_executable args` and `trace -E 
c++_executable args`
print on startup and grep for dlopen calls and the like.
Dec 01 2016
parent reply timotheecour <timothee.cour2 gmail.com> writes:
 Have a look at what `trace -E d_executable args` and `trace -E 
 c++_executable args`
 print on startup and grep for dlopen calls and the like.


do you mean strace?
I have trace on OSX but I'm asking for linux.
Dec 09 2016
parent timotheecour <timothee.cour2 gmail.com> writes:
On Saturday, 10 December 2016 at 02:39:33 UTC, timotheecour wrote:

 Have a look at what `trace -E d_executable args` and `trace -E 
 c++_executable args`
 print on startup and grep for dlopen calls and the like.


 do you mean strace?
 I have trace on OSX but I'm asking for linux.


Looking at the code for $checkModuleCollisions in druntime 
[src/rt/sections_elf_shared.d:859]:

```
  * Check for module collisions. A module in a shared library 
collides
  * with an existing module if it's ModuleInfo is interposed 
(search
  * symbol interposition) by another DSO.  Therefor two modules 
with the
  * same name do not collide if their DSOs are in separate symbol 
resolution
  * chains.
```

Not exactly sure what that means nor how to fix my issue:

```
void some_fun(){
   handle=dlopen2("path/liblib.so", RTLD_LAZY | RTLD_LOCAL);
   // error: The module 'foo' is already defined in 'libmylib.so'
}
```

How would I modify the code to avoid this?
Dec 09 2016