read_fifo.c

UNIX/Linux环境下使用有名管道(FIFO)的例子。

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>

#define BUFFER_SIZE	1024

int main(int argc, char **argv)
{
  int fd;

  if (argc < 2)
  {
    fprintf(stdout, "Usage: %s <filename>\n", argv[0]);
    exit(1);
  }

  //int open(const char *path, int oflag, ...);
  if ((fd = open(argv[1], O_RDONLY)) < 0)
  {
    fprintf(stderr, "open fifo %s for reading failed: %s\n", argv[1], strerror(errno));
    exit(1);
  }

  fprintf(stdout, "open fifo %s for reading successed.\n", argv[0]);

  char buffer[BUFFER_SIZE];
  ssize_t n;

  while (1)
  {
  again:
    //ssize_t read(int fd, void *buf, size_t count);
    if ((n = read(fd, buffer, BUFFER_SIZE)) < 0)
    {
      if (errno == EINTR)
      {
	goto again;
      }
      else
      {
	fprintf(stderr, "read failed on %s: %s\n", argv[1], strerror(errno));
	exit(1);
      }
    }
    else if (n == 0)
    {
      fprintf(stderr, "peer closed fifo.\n");
      break;
    }
    else
    {
      buffer[n] = '\0';
      fprintf(stdout, "read %d bytes from fifo: %s\n", n, buffer);
    }
  }

  return 0;
}