#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <libgen.h>
#include <unistd.h>

static void usage(char *prog_name)
{
????fprintf(stderr, "usage: %s device start count\n", prog_name);
????fprintf(stderr, "example: %s /dev/sda 0 512\n", prog_name);
}

int main(int argc, char *argv[])
{
????char buf[4096];
????int fd = 0;
????int i = 0;
????int j = 0;
????int start = 0;
????int count = 0;
????char *device = NULL;

????if(argc != 4){
????????usage(basename(argv[0]));
????????exit(1);
????}
????
????device = argv[1];
????start = atol(argv[2]);
????count = atol(argv[3]);

????fd = open(device, O_RDONLY);
????if(-1 == fd){
????????fprintf(stderr, "cannot open /dev/hda");
????????exit(1);
????}????
????
????if(lseek(fd, start, SEEK_SET) != start){
????????fprintf(stderr, "cannot seek at %d", start);
????????exit(1);
????}
????
????while(count > 0){
????????int size = count > sizeof(buf) ? sizeof(buf) : count;

????????read(fd, buf, size);
????????
????????/* 每行顯示16個(gè)字節(jié) 每兩個(gè)字節(jié)間以空格分開 */
????????for(i = 0; i < size/16; i++){
????????????fprintf(stdout,"%08x:", i*16+start);
????????????for(j = 0; j < 16; j++){
????????????????fprintf(stdout, " %02x", (int)buf[i*16+j] & 0xFF);????
????????????}
????????????fprintf(stdout,"\n");
????????????fflush(stdout);
????????}
????????count -= size;
????????start += size;
????}
????