info.c

CD驱动器实现的源代码

/*
 * 代码清单3: info.c
 */
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/cdrom.h>

/* CD驱动器对应的设备文件 */
#define DEVICE "/dev/cdrom"

int main() 
{
  int fd;
  int status;
  int track;
  struct cdrom_tochdr header;	/* TOC头部 */
  struct cdrom_tocentry entry;	/* TOC条目 */

  /* 打开设备 */
  fd = open(DEVICE, O_RDONLY);
  if (fd < 0) {
    perror("unable to open " DEVICE);
    exit(1);
  }

  /* 计算音轨数目 */
  status = ioctl(fd, CDROMREADTOCHDR, &header);
  if (status != 0) {
    perror("CDROMREADTOCHDR ioctl failed");
    exit(1);
  }

  /* 输出CD中各条音轨的信息 */
  for (track = 1; track <= header.cdth_trk1; track ++) {
    entry.cdte_track = track;
    entry.cdte_format = CDROM_MSF; /* 采用MSF格式地址 */
    status = ioctl(fd, CDROMREADTOCENTRY, &entry);
    if (status != 0) {
      perror("CDROMREADTOCENTRY ioctl failed");
      exit(1);
    }
    printf("Track%02d: %5d %02d:%02d.%03d %c \n", 
           track, entry.cdte_track,
           entry.cdte_addr.msf.minute,
           entry.cdte_addr.msf.second,
           entry.cdte_addr.msf.frame,
           (entry.cdte_ctrl & CDROM_DATA_TRACK) ? 'D' : 'A');
  }
    
  /* 输出起始(leadout)音轨的信息 */
  entry.cdte_track = CDROM_LEADOUT;
  status = ioctl(fd, CDROMREADTOCENTRY, &entry);
  if (status != 0) {
    perror("CDROMREADTOCENTRY ioctl failed");
    exit(1);
  }
  printf("Track leadout: %02d:%02d.%03d \n", 
         entry.cdte_addr.msf.minute,
         entry.cdte_addr.msf.second,
         entry.cdte_addr.msf.frame);

  /* 关闭设备 */
  status = close(fd);
  if (status != 0) {
    perror("unable to close " DEVICE);
    exit(1);
  }

  return 0;
}