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/* dl_dlopen.xs
*
* Platform: SunOS/Solaris, possibly others which use dlopen.
* Author: Paul Marquess (pmarquess@bfsec.bt.co.uk)
* Created: 10th July 1994
*
* Modified:
* 15th July 1994 - Added code to explicitly save any error messages.
* 3rd August 1994 - Upgraded to v3 spec.
* 9th August 1994 - Changed to use IV
* 10th August 1994 - Tim Bunce: Added RTLD_LAZY, switchable debugging,
* basic FreeBSD support, removed ClearError
*
*/
/* Porting notes:
Definition of Sunos dynamic Linking functions
=============================================
In order to make this implementation easier to understand here is a
quick definition of the SunOS Dynamic Linking functions which are
used here.
dlopen
------
void *
dlopen(path, mode)
char * path;
int mode;
This function takes the name of a dynamic object file and returns
a descriptor which can be used by dlsym later. It returns NULL on
error.
The mode parameter must be set to 1 for Solaris 1 and to
RTLD_LAZY on Solaris 2.
dlsym
------
void *
dlsym(handle, symbol)
void * handle;
char * symbol;
Takes the handle returned from dlopen and the name of a symbol to
get the address of. If the symbol was found a pointer is
returned. It returns NULL on error. If DL_PREPEND_UNDERSCORE is
defined an underscore will be added to the start of symbol. This
is required on some platforms (freebsd).
dlerror
------
char * dlerror()
Returns a null-terminated string which describes the last error
that occurred with either dlopen or dlsym. After each call to
dlerror the error message will be reset to a null pointer. The
SaveError function is used to save the error as soo as it happens.
Return Types
============
In this implementation the two functions, dl_load_file &
dl_find_symbol, return void *. This is because the underlying SunOS
dynamic linker calls also return void *. This is not necessarily
the case for all architectures. For example, some implementation
will want to return a char * for dl_load_file.
If void * is not appropriate for your architecture, you will have to
change the void * to whatever you require. If you are not certain of
how Perl handles C data types, I suggest you start by consulting
Dean Roerich's Perl 5 API document. Also, have a look in the typemap
file (in the ext directory) for a fairly comprehensive list of types
that are already supported. If you are completely stuck, I suggest you
post a message to perl5-porters, comp.lang.perl or if you are really
desperate to me.
Remember when you are making any changes that the return value from
dl_load_file is used as a parameter in the dl_find_symbol
function. Also the return value from find_symbol is used as a parameter
to install_xsub.
Dealing with Error Messages
============================
In order to make the handling of dynamic linking errors as generic as
possible you should store any error messages associated with your
implementation with the StoreError function.
In the case of SunOS the function dlerror returns the error message
associated with the last dynamic link error. As the SunOS dynamic
linker functions dlopen & dlsym both return NULL on error every call
to a SunOS dynamic link routine is coded like this
RETVAL = dlopen(filename, 1) ;
if (RETVAL == NULL)
SaveError("%s",dlerror()) ;
Note that SaveError() takes a printf format string. Use a "%s" as
the first parameter if the error may contain and % characters.
*/
#include "EXTERN.h"
#include "perl.h"
#include "XSUB.h"
#ifdef I_DLFCN
#include <dlfcn.h> /* the dynamic linker include file for Sunos/Solaris */
#else
#include <nlist.h>
#include <link.h>
#endif
#ifndef HAS_DLERROR
#define dlerror() "Unknown error - dlerror() not implemented"
#endif
#include "dlutils.c" /* SaveError() etc */
static void
dl_private_init()
{
(void)dl_generic_private_init();
}
MODULE = DynaLoader PACKAGE = DynaLoader
BOOT:
(void)dl_private_init();
void *
dl_load_file(filename)
char * filename
CODE:
int mode = 1; /* Solaris 1 */
#ifdef RTLD_LAZY
mode = RTLD_LAZY; /* Solaris 2 */
#endif
DLDEBUG(1,fprintf(stderr,"dl_load_file(%s):\n", filename));
RETVAL = dlopen(filename, mode) ;
DLDEBUG(2,fprintf(stderr," libref=%x\n", RETVAL));
ST(0) = sv_newmortal() ;
if (RETVAL == NULL)
SaveError("%s",dlerror()) ;
else
sv_setiv( ST(0), (IV)RETVAL);
void *
dl_find_symbol(libhandle, symbolname)
void * libhandle
char * symbolname
CODE:
#ifdef DLSYM_NEEDS_UNDERSCORE
char symbolname_buf[1024];
symbolname = dl_add_underscore(symbolname, symbolname_buf);
#endif
DLDEBUG(2,fprintf(stderr,"dl_find_symbol(handle=%x, symbol=%s)\n",
libhandle, symbolname));
RETVAL = dlsym(libhandle, symbolname);
DLDEBUG(2,fprintf(stderr," symbolref = %x\n", RETVAL));
ST(0) = sv_newmortal() ;
if (RETVAL == NULL)
SaveError("%s",dlerror()) ;
else
sv_setiv( ST(0), (IV)RETVAL);
void
dl_undef_symbols()
PPCODE:
# These functions should not need changing on any platform:
void
dl_install_xsub(perl_name, symref, filename="$Package")
char * perl_name
void * symref
char * filename
CODE:
DLDEBUG(2,fprintf(stderr,"dl_install_xsub(name=%s, symref=%x)\n",
perl_name, symref));
ST(0)=sv_2mortal(newRV((SV*)newXS(perl_name, (void(*)())symref, filename)));
char *
dl_error()
CODE:
RETVAL = LastError ;
OUTPUT:
RETVAL
# end.
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