angrymlocker.c

/*
 * Copyright (c) 2011 by Stiletto <blasux@blasux.ru>.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * Except as contained in this notice, the name of the copyright holder(s)
 * and author(s) shall not be used in advertising or otherwise to promote
 * the sale, use or other dealings in this Software without prior written
 * authorization from the copyright holder(s) and author(s).
 */

#include <sys/mman.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void __attribute__ ((constructor)) my_load(void);
void __attribute__ ((destructor)) my_unload(void);

static int debug_enabled;

// Called when the library is loaded and before dlopen() returns
void my_load(void)
{
    char* env_debug = getenv("ANGRYMLOCKER_DEBUG");
    char* env_reset = getenv("ANGRYMLOCKER_RESETENV");
    debug_enabled = env_debug && !strcmp(env_debug,"1");

    if ( env_reset && !strcmp(env_debug,"1")) {
	unsetenv("ANGRYMLOCKER_DEBUG");
	unsetenv("ANGRYMLOCKER_RESETENV");
	unsetenv("LD_PRELOAD");
    }

    int res = mlockall(MCL_CURRENT | MCL_FUTURE);
    if (debug_enabled) {
	if (!res)
	    fprintf(stderr,"mlock()'ed entire process's address space.\n");
        else
	    perror("mlockall()");
    }
}

// Called when the library is unloaded and before dlclose()
// returns
void my_unload(void)
{
    int res = munlockall();
    if (debug_enabled) {
	if (!res)
	    fprintf(stderr,"munlock()'ed entire process's address space.\n");
        else
	    perror("munlockall()");
    }
}