Linux: FIFO problem

zak100 · 07-25-2010, 01:29 PM

Hi,
I have written following program. Its not working. Can somebody guide me with this?

Code:

  
//Reader
#include <fcntrl.h>
#include <stdio.h>
#define MSGSIZE 10
main(){
int fd, len;
char msgbuf[MSGSIZE+1];
if((fd=open("testfile",O_RDWR))<0)
perror("pipe open failed");
for(;;){
len=read(fd, msgbuf, MSGSIZE+1);
msgbuf[len]='\0';
printf("msg received =%s\n", msgbuf);
}}

//Writer
#include <fcntrl.h>
#include <stdio.h>
#define MSGSIZE 10
main(){
main(argc, argv)
int argc, char *argv[];{
int fd, j, nwrite, len;
char msgbuf[MSGSIZE];
if(argc <2) { printf("Error"); exit(-1);
}
if((fd=open("testfile", O_WRONLY))<0)
perror("fifo open failed");
for(j=1; j<argc;++j){
strcpy(msgbuf,argv[j]);
len=strlen(msgbuf);
if((nwrite=write(fd, msgbuf, len))<=0)
perror("message write failed");
}
exit(0);
}

I have first created the FIFO

Code:

  
$/bin/mknod testfile p

I am not getting three messages printed by Reader. Also terminal is behaving abnormally.

Can somebody plz help me with problem? There is no compilation error.

Zulfi.

zirias · 07-25-2010, 01:46 PM

This MAY sound a little rude, but after all, we're all lazy, so ... post a decently formatted version, please.

Oh and .. just a quick notice .. if you define the buffer being "MSGSIZE+1" bytes and you want the last byte be a null-byte ... you should only read a maximum of "MSGSIZE" bytes, not "MSGSIZE+1"

zak100 · 07-25-2010, 11:46 PM

[CODE]
//Reader
#include <fcntrl.h>
#include <stdio.h>
#define MSGSIZE 10
main(){
int fd, len;
char msgbuf[MSGSIZE+1];
if((fd=open("testfile",O_RDWR))<0)
perror("pipe open failed");
for(;

{
len=read(fd, msgbuf, MSGSIZE+1);
msgbuf[len]='\0';
printf("msg received =%s\n", msgbuf);
}
}

//Writer
#include <fcntrl.h>
#include <stdio.h>
#define MSGSIZE 10
main(argc, argv)
int argc, char *argv[];
{
int fd, j, nwrite, len;
char msgbuf[MSGSIZE];
if(argc <2) {
printf("Error");
exit(-1);
}
if((fd=open("testfile", O_WRONLY))<0)
perror("fifo open failed");
for(j=1; j<argc;++j){
strcpy(msgbuf,argv[j]);
len=strlen(msgbuf);
if((nwrite=write(fd, msgbuf, len))<=0)
perror("message write failed");
}
exit(0);
}

[\CODE]

I hope now its in proper format.
Plz help me with this.
Zulfi.

zak100 · 08-09-2010, 01:34 PM

Kindly provide me help with this.

Zulfi.

Sergei Steshenko · 08-09-2010, 01:38 PM

Quote:

Originally Posted by zak100

[CODE]
//Reader
#include <fcntrl.h>
#include <stdio.h>
#define MSGSIZE 10
main(){
int fd, len;
char msgbuf[MSGSIZE+1];
if((fd=open("testfile",O_RDWR))<0)
perror("pipe open failed");
for(;

{
len=read(fd, msgbuf, MSGSIZE+1);
msgbuf[len]='\0';
printf("msg received =%s\n", msgbuf);
}
}

//Writer
#include <fcntrl.h>
#include <stdio.h>
#define MSGSIZE 10
main(argc, argv)
int argc, char *argv[];
{
int fd, j, nwrite, len;
char msgbuf[MSGSIZE];
if(argc <2) {
printf("Error");
exit(-1);
}
if((fd=open("testfile", O_WRONLY))<0)
perror("fifo open failed");
for(j=1; j<argc;++j){
strcpy(msgbuf,argv[j]);
len=strlen(msgbuf);
if((nwrite=write(fd, msgbuf, len))<=0)
perror("message write failed");
}
exit(0);
}

[\CODE]

I hope now its in proper format.
Plz help me with this.
Zulfi.

No, it isn't - in the last tag you used backslash instead of forward slash.