学步园

  1 /* by hugang at 6/8 9:40 */
  2 /* mod by jevan at 31/8 11:56 */
  3 /* read some disk a sector */
  4 #include <stdio.h>
  5 #include <errno.h>
  6 #include <unistd.h>
  7 #include <sys/types.h>
  8 #include <sys/stat.h>
  9 #include <fcntl.h>
 10 
 11 #include <linux/fs.h>
 12 
 13 int
 14 get_disk_sector (int fd)
 15 {
 16   int sectorsize;
 17 
 18   ioctl (fd, BLKSSZGET, &sectorsize);
 19 
 20   return sectorsize;
 21 }
 22 
 23 /** 
 24 * read_disk_sector: 
 25 * @dev: raw disk FILE * 
 26 * @sector: 
 27 * return is the disk sectorsize 
 28 * */
 29 extern int errno;
 30 int
 31 read_disk_sector (int fd, unsigned long sector, char **p)
 32 {
 33   int sectorsize;
 34   FILE *fp;
 35 
 36 /* get disk sector size */
 37   sectorsize = get_disk_sector (fd);
 38   if (sectorsize == 0)
 39     {
 40       fprintf (stderr, "get disk sector size failed\n");
 41       return (-1);
 42     }
 43 
 44 /* seek it */
 45   lseek (fd, 0, SEEK_SET);
 46   if (lseek (fd, (sectorsize * sector), SEEK_CUR) == -1)
 47     {
 48       fprintf (stderr, "seek to %d failed\n", sectorsize * sector);
 49       return (-1);
 50     }
 51 /* read it */
 52   *p = (char *) malloc (sectorsize);
 53   if (*p == NULL)
 54     {
 55       fprintf (stderr, "malloc memory failed\n");
 56       return (-1);
 57     }
 58 
 59   return read (fd, *p, sectorsize);
 60 }
 61 
 62 /* dump data for display */
 63 void
 64 dump_disk_sector (char *p, int size)
 65 {
 66   int i;
 67   for (i = 0; i < size; i++)
 68     {
 69       if (i % 16 == 0 && i != 0)
 70     printf ("\n");
 71       printf ("%2x ",/* (unsigned int) p & 0xff*/(unsigned char)*p++);
 72     }
 73 
 74   printf ("\n");
 75   return;
 76 }
 77 
 78 int
 79 main (int argc,char* argv[])
 80 {
 81   char *d;
 82   int size;
 83   int fd;
 84   char *dev = "/dev/sda";
 85 
 86 /* open it */
 87   fd = open (dev, O_RDONLY);
 88   if (fd == -1)
 89     {
 90       fprintf (stderr, "open %s failed %s\n", dev, strerror (errno));
 91       return (-1);
 92     }
 93 
 94   size = read_disk_sector (fd, atoi(argv[1]), &d);
 95 
 96   close (fd);
 97 
 98   if (size <= 0)
 99     return (0);
100 
101   dump_disk_sector (d, size);
102 
103   free (d);
104 
105   return (0);
106 }