gistfile1.txt

#include <sys/types.h>
#include <sys/stat.h>
#include <stdint.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>

#define __u8 uint8_t
#define __u32 uint32_t
#define __u64 uint64_t

#pragma pack(push,1)
struct ploop_pvd_header
{
        __u8  m_Sig[16];          /* Signature */
        __u32 m_Type;             /* Disk type */
        __u32 m_Heads;            /* heads count */
        __u32 m_Cylinders;        /* tracks count */
        __u32 m_Sectors;          /* Sectors per track count */
        __u32 m_Size;             /* Size of disk in tracks */
        union {                   /* Size of disk in 512-byte sectors */
                struct {  
                        __u32 m_SizeInSectors_v1;
                        __u32 Unused;
                };      
                __u64 m_SizeInSectors_v2;
        };      
        __u32 m_DiskInUse;        /* Disk in use */
        __u32 m_FirstBlockOffset; /* First data block offset (in sectors) */
        __u32 m_Flags;            /* Misc flags */
        __u8  m_Reserved[8];      /* Reserved */
};
#pragma pack(pop)

main(int argc, char *argv[])
{
	char version[17] = { 0 };
	struct ploop_pvd_header hdr;
	unsigned long i;
	int fd;

	if (argc != 2) {
		errno = -EINVAL;
		perror("arguments");
		exit(1);
	}

	fd = open(argv[1], O_RDONLY);
	if (fd < 0) {
		perror("open");
		exit(1);
	}

	read(fd, &hdr, sizeof(hdr));
	memcpy(version, &hdr.m_Sig, 16);

	printf("m_Type=%u, m_Sig=%s, m_Sectors=%u, m_Size=%u, m_SizeInSectors_v2=%lu, m_FirstBlockOffset=%u\n",
		hdr.m_Type, version, hdr.m_Sectors, hdr.m_Size, le64toh(hdr.m_SizeInSectors_v2), hdr.m_FirstBlockOffset);

	lseek(fd, 64, SEEK_SET);
	
	for (i = 0; i < hdr.m_Size; i++) {
		unsigned int blk;
		read(fd, &blk, sizeof(blk));
		printf("%d->%d\n", i, blk);
	}
}