C_och_UNIX/Lab4/dbserver.c

#include "db.h"

void Kill_Process() {
	kill(0, SIGTERM);
	exit(0);
}

void P(char *lockfile) { /* Proberen */  	
   int tempfd;
   while((tempfd = creat(lockfile, 0)) < 0); /* Försök skapa låsfilen */
   close(tempfd);
}

void V(char *lockfile) { /* Verhogen */
	unlink(lockfile);
}

printsin(struct sockaddr_in *sin, char *m1, char *m2 ) {
	struct hostent *gethostbyaddr(), *h;
	printf ("%s %s\n", m1, m2);
	printf ("Family %d addr %x port %d\n", sin -> sin_family,
	ntohl(sin -> sin_addr.s_addr), ntohs(sin -> sin_port));
	h = gethostbyaddr((char *)&sin->sin_addr, sizeof(int), AF_INET);
	printf ("Symbolic host name <%s>\n",h->h_name);
}

void doAdd(msg *myMsg) {
	int fd, i=0;
  	printf("Adding %s\n", myMsg->name);
	
	P(READLOCK);
	if((fd = open(FILENAME, O_CREAT|O_WRONLY|O_APPEND, PERMS)) < 0) {
		myMsg->op = NACK; /* Return error to client */
		exit(1);
	}
	write(fd, &myMsg->nr, NRSIZE);
	write(fd, &myMsg->name, NAMESIZE);	

	if((close(fd)) < 0) {
		myMsg->op = NACK;
		V(READLOCK);
		return;
	}
	myMsg->op = ACK;
	V(READLOCK);
}

void doDel(msg *myMsg) {
	int i=0, j=0, file, temp;
	struct stat st1;
	struct stat st2;	
	long a, b;
	char c, nr[NRSIZE], name[NAMESIZE];
	
	P(READLOCK);
	P(WRITELOCK);
	if((file = open(FILENAME, O_RDONLY)) < 0) {
		myMsg->op = NACK;
		return;
	}
	if((temp = open(TMPFILE, O_RDWR|O_CREAT|O_TRUNC, PERMS)) < 0) {
		myMsg->op = NACK;
		return;
	}
	
	while(read(file, nr, NRSIZE) > 0) {
		read(file, name, NAMESIZE);
		if(strcmp(nr, myMsg->nr) != 0) {
			write(temp, nr, NRSIZE);
			write(temp, name, NAMESIZE);
		}
	}
	fstat(file, &st1);
	a = st1.st_size;
	fstat(temp, &st2);
	b = st2.st_size;
	
	if((close(file)) < 0) {
		myMsg->op = NACK;
		return;
	}
	if((close(temp)) < 0) {
		myMsg->op = NACK;
		return;
	}
	if((temp = open(TMPFILE, O_RDONLY)) < 0) {
		myMsg->op = NACK;
		return;
	}
	if((file = open(FILENAME, O_RDWR|O_CREAT|O_TRUNC, PERMS)) < 0) {
		myMsg->op = NACK;
		return;
	}
		
	while(read(temp, &c ,1) > 0){
		write(file, &c, 1);
	}
	if((close(file)) < 0) {
		myMsg->op = NACK;
		return;
	}
	if((close(temp)) < 0) {
		myMsg->op = NACK;
		return;
	}
	if((unlink(TMPFILE)) < 0) {
		myMsg->op = NACK;
		return;
	}
	V(WRITELOCK);
	V(READLOCK);
	
	if(a == b) {
		myMsg->op = NACK;
		return;
	}
	myMsg->op = ACK;
}

void doFindNumber(msg *myMsg) {
	int file;
	char nr[NRSIZE], name[NAMESIZE];	
	
	P(READLOCK);
	if((file = open(FILENAME, O_RDONLY)) < 0) {
		myMsg->op = NACK;
		return;
	}
	
	while(read(file, nr, NRSIZE) > 0){
		read(file, name, NAMESIZE);
		if(strcmp(name, myMsg->name) == 0) {
			myMsg->op = PRN;
			strcpy(myMsg->nr, nr);
			V(READLOCK);
			return;
		}
	}
	myMsg->op = NACK;
   close(file);
   V(READLOCK);
   return;
}

void doFindName(msg *myMsg) {
	int file;
	char nr[NRSIZE], name[NAMESIZE];	
	
	P(READLOCK);
	if((file = open(FILENAME, O_RDONLY)) < 0) {
		myMsg->op = NACK;
		return;
	}
	
	while(read(file, nr, NRSIZE) > 0){
		read(file, name, NAMESIZE);
		printf("\n nr=%s, myMsg->nr=%s",nr, myMsg->nr);
		if(strcmp(nr, myMsg->nr) == 0) {
			myMsg->op = PRN;
			strcpy(myMsg->name, name);
			V(READLOCK);
			return;
		}
	}
   close(file);
   V(READLOCK);	
	myMsg->op = NACK;
}

void doExit(msg *myMsg, int data_sockfd) {
	printf("Quitting...\n");
	close(data_sockfd);
	exit(0);
}

main() {
	int listener, childpid, data_sockfd, status, client_length, length;
	msg myMsg;
	struct sockaddr_in srvr_addr, client_addr;
	signal(SIGCHLD, SIG_IGN);
	signal(SIGINT, Kill_Process);
	/*signal(SIGTERM, Kill_Process);*/

	if((listener = socket( AF_INET, SOCK_STREAM, 0 )) < 0 ) {
		perror("server: can't open stream socket");
		exit(0);
	}
	bzero((char *) &srvr_addr, sizeof(srvr_addr));
	srvr_addr.sin_family = AF_INET;
	srvr_addr.sin_addr.s_addr = htons(INADDR_ANY);
	srvr_addr.sin_port = 27015;

	if(bind(listener, (struct sockaddr *)&srvr_addr, sizeof(srvr_addr)) < 0) {
		perror("server: can't bind local address");
		exit(0);
	}
	/* Print out the port number assigned to this process by bind(). */
	length = sizeof(srvr_addr);
	
	if(getsockname(listener, (struct sockaddr *)&srvr_addr, &length) < 0) {
		perror("server: can't get sockname");
		exit(0);
	}
	printf("Port number %d\n", ntohs(srvr_addr.sin_port));
	listen(listener,10);
	
	for(;;) {
		/* Wait for a connection from a client process */
		client_length = sizeof(client_addr);
		if ((data_sockfd=accept(listener,
	       (struct sockaddr *)&client_addr, &length)) < 0) {
			perror("server: accept error");
			exit(0);
		}

		printsin(&client_addr,"\nRSTREAM", "accepted connection from");
		if((childpid = fork()) < 0) {
			perror("server: fork error");
			exit(0);
		}
		else if(childpid == 0) { /* Child process */	
			close(listener);
			while(1) {	
				read(data_sockfd, &myMsg, sizeof(myMsg));

				switch(myMsg.op) {
					case 1: 	doAdd(&myMsg);
							  	write(data_sockfd, &myMsg, sizeof(myMsg));
							  	break;
					case 2: 	doDel(&myMsg);
							 	write(data_sockfd, &myMsg, sizeof(myMsg));
								break;
					case 3:	doFindNumber(&myMsg);
							 	write(data_sockfd, &myMsg, sizeof(myMsg));
								break;
					case 4:	doFindName(&myMsg);
							 	write(data_sockfd, &myMsg, sizeof(myMsg));
								break;																
					case 5: 	doExit(&myMsg, data_sockfd);
										
					default: break;
				}
				myMsg.op = ACK; /* töm struktens op så den inte är kvar till switchen */
			}
		}
	}
}