Thread: warning problem: passing argument 2 of ‘signal’ from incompatible pointer type

hello,
I am trying for watch syn packet on my network. After compile my program getting this problem

warning: passing argument 2 of ‘signal’ from incompatible pointer type

Actually i used header file #include <linux.h> then getting this warning here

Code:

int slickPing(amount,sock,dest)
int amount,sock;
char *dest;
{

	int alarmHandler();
	unsigned nameResolve(char *);
	
	register int retcode,j=0;
	struct icmphdr *icmp;
	struct sockaddr_in sin;
	unsigned char sendICMPpak[MAXPAK]={0};
	unsigned short pakID=getpid()&0xffff;

	struct ippkt{
   		struct iphdr ip;
   		struct icmphdr icmp;
   		char buffer[MAXPAK];
	}pkt;

	bzero((char *)&sin,sizeof(sin));
	sin.sin_family=AF_INET;
	sin.sin_addr.s_addr=nameResolve(dest);

		/* ICMP Packet assembly  */
	/* We let the kernel create our IP header as it is legit */

	icmp=(struct icmphdr *)sendICMPpak;
	icmp->type=ICMP_ECHO;			/* Requesting an Echo */
	icmp->code=0;				/* 0 for ICMP ECHO/ECHO_REPLY */
	icmp->un.echo.id=pakID;			/* To identify upon return */	
	icmp->un.echo.sequence=0;		/* Not used for us */
	icmp->checksum=in_cksum((unsigned short *)icmp,64);

	fprintf(stderr,"sending ICMP_ECHO packets: ");
	for(;j<amount;j++){
		usleep(ICMPSLEEP);		/* For good measure */
		retcode=sendto(sock,sendICMPpak,64,0,(struct sockaddr *)&sin,sizeof(sin));
		if(retcode<0||retcode!=64)
			if(retcode<0){
				perror("ICMP sendto err");
				exit(1);
			}
			else fprintf(stderr,"Only wrote %d bytes",retcode);
		else fprintf(stderr,".");
	}
	HANDLERCODE=1;
	signal(SIGALRM,alarmHandler);	/* catch the ALARM and handle it */
	fprintf(stderr,"\nSetting alarm timeout for 10 seconds...\n");
	alarm(10);	/* ALARM is set b/c read() will block forever if no */
	while(1){	/* packets arrive...   (which is what we want....)  */
		read(sock,(struct ippkt *)&pkt,MAXPAK-1);
  		if(pkt.icmp.type==ICMP_ECHOREPLY&&icmp->un.echo.id==pakID){
			if(!HANDLERCODE)return(0);
			return(1);
		}
  	}	
}


/* 
 *	SIGALRM signal handler.  Souper simple.
 */ 
int alarmHandler(){

	HANDLERCODE=0;		/* shame on me for using global vars */
	alarm(0);
	signal(SIGALRM,SIG_DFL);
	return(0);
}

but i thought may be header file should be #include <linux/signal.h> then getting this problem

Code:

In file included from /usr/include/asm/signal.h:7,
                 from /usr/include/linux/signal.h:4,
                 from neptune.c:67:
/usr/include/asm-i386/signal.h:13: error: conflicting types for ‘sigset_t’
/usr/include/sys/select.h:38: error: previous declaration of ‘sigset_t’ was here

I checked all the path signal.h. all in the right place.
please help me for solve this problem.

According to man signal, the second parameter of signal should be a pointer-to-function-returning-void-taking-int, while you have pointer-to-function-returning-int-taking-void, which is not the same thing.