trying putting newlines in the strings like this: 

   "receive overflow\n" 

----- Original Message ----- 
From: "Edward King" <> 
Sent: Monday, January 5, 2009 2:29:23 AM GMT -05:00 US/Canada Eastern 
Subject: why printf() don't work? 

I use FreeBSD7.0,and use signal,like follows: signal(SIGHUP,sig_hup); 
signal(SIGIO,sig_io); when I run call following code,it can run,but I find a 
puzzled question,it should print some information,such as printf("execute 
main()") will print execute main(),but in fact,printf fuction print none!!! Why 
printf function do not go work? my code is follows: #include "sys/ioctl.h" 
#include "unp.h" static int sockfd; #define QSIZE 8 #define MAXDG 4096 typedef 
struct{ void *dg_data; size_t dg_len; struct sockaddr *dg_sa; socklen_t 
dg_salen; }DG; static DG dg[QSIZE]; static long cntread[QSIZE+1]; static int 
iget; static int iput; static int nqueue; static socklen_t clilen; static void 
sig_io(int); static void sig_hup(int); int main(int argc,char **argv){ 
printf("execute main()"); int sockfd; struct sockaddr_in servaddr,cliaddr; 
sockfd=socket(AF_INET,SOCK_DGRAM,0); bzero(&servaddr,sizeof(servaddr)); 
servaddr.sin_family=AF_INET; servaddr.sin_addr.s_addr=htonl(INADDR_ANY); 
servaddr.sin_port=htons(SERV_PORT); bind(sockfd,(SA 
*)&servaddr,sizeof(servaddr)); dg_echo(sockfd,(SA *)&cliaddr,sizeof(cliaddr)); 
} void dg_echo(int sockfd_arg,SA *pcliaddr,socklen_t clilen_arg){ 
printf("called dg_echo"); int i; const int on=1; sigset_t 
zeromask,newmask,oldmask; sockfd=sockfd_arg; clilen=clilen_arg; for(i=0;i 
=QSIZE) iget=0; sigprocmask(SIG_BLOCK,&newmask,&oldmask); nqueue--; } } static 
void sig_io(int signo){ printf("sig_io called"); ssize_t len; int nread; DG 
*ptr; for(nread=0;;){ if(nqueue>=QSIZE) err_quit("receive overflow"); 
ptr=&dg[iput]; ptr->dg_salen=clilen; 
len=recvfrom(sockfd,ptr->dg_data,MAXDG,0,ptr->dg_sa,&ptr->dg_salen); if(len<0){ 
if(errno==EWOULDBLOCK) break; else err_sys("recvfrom error"); } 
ptr->dg_len=len; nread++; nqueue++; if(++iput>=QSIZE) iput=0; } 
cntread[nread]++; } static void sig_hup(int signo){ printf("sig_hup called"); 
int i; for(i=0;i<=QSIZE;i++) printf("cntread[%d]=%ld\n",i,cntread[i]); } 
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