fifo.c

/**
 * desc: Fifo example, writes and reads depending on invocation name
 * compile: gcc -o fifo-read fifo.c; ln -svf fifo-read fifo-write
 */
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>

#define BUF_LEN 256
static char buf[BUF_LEN];

#define FIFO "MyFifo"

int main(int argc, char **argv)
{
        int pipe_fd;
        int rval;
        int n;
        fd_set rfds;

        rval = mkfifo(FIFO, 0777);

        if (rval != 0)
                fprintf(stderr, "Cannot create fifo ERROR: %s\n", strerror(errno));


        if (!strncmp("fifo-read", argv[0], 9)) {
                do  {
                        puts("read");
                        pipe_fd = open(FIFO, S_IRUSR);
                        if (pipe_fd < 0) {
                                fprintf(stderr, "Cannot open fifo\n");
                                exit(EXIT_FAILURE);
                        }
                        while ((n = read(pipe_fd, buf, BUF_LEN)) > 0) {

                                printf("\"%*s\"\n", n, buf);
                        }
                        close(pipe_fd);
                } while (1);
        } else if (!strncmp("fifo-write", argv[0], 10)) {
                do {
                        puts("read");
                        pipe_fd = open(FIFO, S_IWUSR);
                        if (pipe_fd < 0) {
                                fprintf(stderr, "Cannot open fifo\n");
                                exit(EXIT_FAILURE);
                        }
                        while ((n = read(0, buf, BUF_LEN)) > 0) { /* 0 == stdin */
                                write(pipe_fd, buf, n);
                        }

                        close(pipe_fd);
                } while (1);
        } else {
                fprintf(stderr, "Wrong program name, use fifo-write or fifo-read instead\n");
                return 0;
        }

        return 0;
}