Can't make a named Pipe - c

Question

I'm trying to make a program that uses the FIFO in C under Linux, here the code :
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#define TFIFO "tfifo"
#define BUFFLEN 100
#define MODE (S_IWUSR|S_IRUSR | S_IWGRP | S_IRGRP| S_IROTH|S_IWOTH)
int main (){
pid_t npid;
size_t anz;
int fds;
char* fifo_name = TFIFO;
char msgbuf[BUFFLEN] ="\0";
if( mkfifo(fifo_name,MODE)<0){
printf(" Couldn't make the fifo \n");
return -1;
}
npid = fork();
if( npid > 0){
printf( "Parent process \n");
if((fds = open(fifo_name,O_WRONLY))== -1 ){
printf(" Couldn't write in the fifo \n" );
return -1;
}
printf( " Parent Process: waiting for the message \n ");
fflush(stdin);
scanf("%[^\n]",msgbuf);
anz = strlen(msgbuf)+1;
write(fds,msgbuf,anz);
printf(" Parent process : EXIT \n ");
}else {
if(fds = open(fifo_name,O_RDONLY) ==-1){
printf("Couldn't open the fifo for reading \n");
return -1 ;
}
printf(" Child process received : \n ");
if(( anz = read(fds,msgbuf,sizeof(msgbuf)))!=-1){
printf(" %s \n",msgbuf);
remove(fifo_name);
printf(" Exit the child process \n");
}
else {
printf( " DIGGA FATLAE ERROR \n ");
}
}
}
when I run the proram, it stops in mkfifo it return a negativ return value ?? I don't get why ? any idea ?
thanks in advance !

Answer 1

You can get the error number this way:
#include <errno.h>
...
if (mkfifo(fifo_name, MODE) < 0) {
printf("Couldn't make the fifo, error = %d\n", errno);
return -1;
}
You can also get a text description for the error by using strerror().
#include <errno.h>
#include <string.h>
...
if (mkfifo(fifo_name, MODE) < 0) {
printf("Couldn't make the fifo, %s\n", strerror(errno));
return -1;
}
Important: always read errno before any other library call! Subsequent calls may change it.