/*
    Copyright (C) 2010 Andreas Baumann <abaumann@yahoo.com>

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include "library/loader.h"
#include "port/sys_internal.h"
#include "port/unused.h"

#include "port/stdlib.h"		/* for malloc, free */
#include "port/stdio.h"			/* for snprintf */
#include "port/gettext.h"		/* for i18n */
#include "port/string.h"		/* for strncpy */

#ifdef HAVE_DLFCN
#include <dlfcn.h>                      /* for dlopen. dlclose functions */
#endif

#define INTERNAL_ERRBUF_SIZE 256

struct wolf_library_t {
	void *handle;				/**< the OS handle for the library */
	char errbuf[INTERNAL_ERRBUF_SIZE];	/**< internal buffer to hold the error message
						 *   we get with dlerror */
};

wolf_library_p wolf_library_load( const char *name, wolf_error_t *error ) {
	wolf_library_p l;
	int flags = 0;

	l = (struct wolf_library_t *)malloc( sizeof ( struct wolf_library_t ) );
	if( l == NULL ) {
		*error = WOLF_ERR_OUT_OF_MEMORY;
		return NULL;
	}

#if defined HAVE_DLFCN
	/* TODO: Apache has a flags variable and a direct parameter version, find out why..
	 * also make up our mind how many flags we should "leak" to the application layer
	 */
	flags = RTLD_NOW | RTLD_LOCAL;

	l->handle = dlopen( name, flags );
	if( l->handle == NULL ) {
		strncpy( l->errbuf, dlerror( ), INTERNAL_ERRBUF_SIZE );
		*error = WOLF_ERR_INTERNAL;
		return l;
	}
#else
#error Not using DLFCN as shared loader. Port first!
#endif

	*error = WOLF_OK;
	return l;
}

wolf_error_t wolf_library_unload( wolf_library_p l ) {
	int res = 0;

	if( l == NULL || l->handle == NULL ) {
		return WOLF_ERR_INVALID_STATE;
	}

	res = dlclose( l->handle );
	if( res != 0 ) {
		strncpy( l->errbuf, dlerror( ), INTERNAL_ERRBUF_SIZE );
		return WOLF_ERR_INTERNAL;
	}

	free( l );
	l = NULL;

	return WOLF_OK;
}

char *wolf_library_errmsg( const wolf_error_t error, const wolf_library_p library, char *buf, size_t buflen ) {
	(void)wolf_error_msg( error, buf, buflen );
	strncat( buf, " - ", buflen - strlen( buf ) );
	if( error == WOLF_ERR_INTERNAL ) {
		strncat( buf, library->errbuf, buflen - strlen( buf ) );
	}

	return buf;
}

void *wolf_library_get( const wolf_library_p l, const char *name, wolf_error_t *error ) {
	void *ret;

	ret = dlsym( l->handle, name );

	*error = WOLF_OK;	
	return ret;
}