/*
 * Copyright (c) 2004 Teodor Sigaev <teodor@sigaev.ru>
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *        notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *        notice, this list of conditions and the following disclaimer in the
 *        documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the author nor the names of any co-contributors
 *        may be used to endorse or promote products derived from this software
 *        without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY CONTRIBUTORS ``AS IS'' AND ANY EXPRESS
 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER
 * IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN
 * IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h> 
#include <sys/ipc.h>
#include <sys/sem.h>
#include <sys/shm.h>
#include <errno.h>

#include "tlog.h"
#include "shmem.h"

#define KEY 101
#define PATH	"/bin"

void *
attachSharedMemory(int key, char *path, int size, int rdonly) {
	key_t shm_key;
	int shm_id, flags=0;
	void *shm;

	if ( size>0 && rdonly )
		return NULL;

	shm_key = ftok( (path) ? path : PATH, (key) ? key : KEY);    /* Get IPC key */
	if ((int) shm_key == -1) 
		tlog(TL_CRIT|TL_EXIT, "Ftok error: %s", strerror(errno));

	if (size > 0) 
		flags = IPC_CREAT | IPC_EXCL | 0644;

	shm_id = shmget(shm_key, size, flags); /* Get SHM segment */
	if (shm_id == -1) {
		if ( errno == EEXIST || errno == ENOENT )
			return NULL;
		else
			 tlog(TL_CRIT|TL_EXIT, "shmget error: %s", strerror(errno));
	}

	flags = ( rdonly ) ? SHM_RDONLY : 0;

	shm = shmat(shm_id, 0, flags);      /* Attach SHM segment */
	if ( shm == (void*)-1 )
		tlog(TL_CRIT|TL_EXIT, "shmat error: %s", strerror(errno));
 
	return shm;
}
 
void 
detachSharedMemory(void *shm) {
	if ( shmdt(shm) == -1 )
		tlog(TL_CRIT, "shmdt error: %s", strerror(errno));
}

int
attachSemaphore(int key, char *path) {
	key_t shm_key;
	int sem_id;

	shm_key = ftok( (path) ? path : PATH, (key) ? key : KEY);    /* Get IPC key */
	if ((int) shm_key == -1)
		tlog(TL_CRIT|TL_EXIT, "Ftok error: %s", strerror(errno));

	sem_id = semget(shm_key, 1, 0);
	if ( sem_id == -1 ) {
		if ( errno == ENOENT ) { /* not exists */
			sem_id = semget(shm_key, 1, IPC_CREAT | IPC_EXCL | 0644);
			if ( sem_id == -1 )
				tlog(TL_CRIT|TL_EXIT, "semget error: %s", strerror(errno));
			if ( semctl( sem_id, 0, SETVAL, 1 ) == -1 )
				tlog(TL_CRIT|TL_EXIT, "sysctl error: %s", strerror(errno));
		} else 
			tlog(TL_CRIT|TL_EXIT, "semget error: %s", strerror(errno));
	}
	return sem_id;
}

void releaseSemaphore(int sem_id) {
	struct sembuf sem;

	sem.sem_num = 0;
	sem.sem_flg = 0;
	sem.sem_op =  1;

	if (semop(sem_id, &sem, 1) == -1) 
		tlog(TL_CRIT|TL_EXIT, "semop error: %s", strerror(errno));
}
	
void lockSemaphore(int sem_id) {
	struct sembuf sem;

	sem.sem_num = 0;
	sem.sem_flg = 0;
	sem.sem_op = -1;

	if (semop(sem_id, &sem, 1) == -1) 
		tlog(TL_CRIT|TL_EXIT, "semop error: %s", strerror(errno));
}