1. Errors using multiple euphoria shared libraries

  • Posted by raseu May 24, 2012
  • 1012 views

eui Linux Version (Linux Ubuntu)

Euphoria Interpreter v4.1.0 development
32-bit Linux, Using System Memory
Revision Date: unknown, Id: 0:unknown

eui windows Version

Euphoria Interpreter v4.1.0 development
32-bit Windows, Using System Memory
Revision Date: unknown, Id: 0:unknown

Using the above version of euphoria under linux, there are issues regarding the
execution of exported routines when multiple euphoria libraries are loaded
within a program.

Given the following two programs compiled as euphoria shared libraries

--// compile as shared library 
--// 
--// $ euc -so lib1.e 
include std/os.e 
 
export procedure lib1_export() 
   printf(1, "inside lib1_export()\n") 
end procedure

and

--// compile as shared library 
--// 
--// $ euc -so lib2.e 
include std/os.e 
 
export procedure lib2_export() 
   printf(1, "inside lib2_export()\n") 
end procedure

and the following test program 

--// run 
--// 
--// $ eui test.ex 
include std/dll.e 
include std/machine.e 
 
ifdef WINDOWS then 
   constant lib1 = open_dll("lib1.dll") 
   constant lib2 = open_dll("lib2.dll") 
elsedef 
   constant lib1 = open_dll("lib1.so") 
   constant lib2 = open_dll("lib2.so") 
end ifdef 
 
   constant lib1_export = define_c_proc(lib1, "lib1_export", {}) 
   constant lib2_export = define_c_proc(lib2, "lib2_export", {}) 
 
   ? { lib1, lib2, lib1_export, lib2_export } 
 
   c_proc(lib1_export, {}) 
   c_proc(lib2_export, {})

Windows provides the following output as expected

{7733248,31588352,28,29}
inside lib1_export()
inside lib2_export()

Linux provides the following undesired output

{139554136,139234544,19,20}
inside lib1_export()
inside lib1_export()

Is this a euphoria issue under linux?, or an issue with the way
linux loads shared libraries with all symbols exported as default?

I am guessing that because both shared libraries under linux share
a lot of underlying euphoria library routines that the system cannot
resolve linkage definitions correctly?

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2. Re: Errors using multiple euphoria shared libraries

  • Posted by mattlewis (admin) May 24, 2012
  • 984 views
raseu said...

Is this a euphoria issue under linux?, or an issue with the way
linux loads shared libraries with all symbols exported as default?

I am guessing that because both shared libraries under linux share
a lot of underlying euphoria library routines that the system cannot
resolve linkage definitions correctly?

It does not appear to be a euphoria interpreter issue. I wrote some C code to test: 

// lib1.h 
void lib1_export(); 
 
// lib2.h 
void lib2_export(); 
 
// lib.c 
// gcc lib.c -l1 -l2 -o test 
#include "lib1.h" 
#include "lib2.h" 
 
int main(){ 
	lib1_export(); 
	lib2_export(); 
	return 0; 
}

I get the same result. If I switch the linking order libraries, then both calls go to lib2. I added define_c_var() calls to see what was being reported for lib1_export and lib2_export, and the pointers returned were different, however the memory pointed to was identical (a jump table?).

Also: 

$ nm lib1.so | grep lib 
0000000000011d20 T _1lib1_export 
0000000000016ae0 T _3std_library_address 
0000000000011d20 T lib1_export 
 
$ nm lib2.so | grep lib 
0000000000011d20 T _1lib2_export 
0000000000016ae0 T _3std_library_address 
0000000000011d20 T lib2_export

I guess that they aren't being relocated properly when linked. I built simple shared libs from source: 

// lib1.c 
 gcc -shared -fPIC lib1.c -o lib1.so 
#include <stdio.h> 
 
void _1lib1_export(){ 
	puts("inside C lib1_export"); 
} 
void lib1_export() __attribute__ ((alias ("_1lib1_export"))); 
 
// lib2.c 
//  gcc -shared -fPIC lib2.c -o lib2.so 
#include <stdio.h> 
 
void _1lib1_export(){ 
	puts("inside C lib1_export"); 
} 
void lib1_export() __attribute__ ((alias ("_1lib1_export")));

Those worked as expected, so I'm not sure why the euphoria translated libraries aren't working...

Matt

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