/*blkdump -- dumps blocks from a fileWritten by Matthew Veety, circa 2010.Under BSD license*/ #include <u.h>#include <libc.h> intprintblock(u8int *block, uint len){	u16int i; 	for(i = 0; i < len; i++){		if(i%16 == 0){			if(i != 0)				print("\n");			print("  %u4.hx: ", i);		}		print("%u2.hhx ", block[i]);	}	return 0;} voidusage(void){	fprint(2, "usage: blkdmp -f file [-o offset] [-n nblocks] [-b bsize]\n");	exits("usage");} voidmain(int argc, char *argv[]){	uint nblocks = 1;	char *fn = nil;	uint bsize = 512;	u64int offset = 0; 	int fd;	u8int *blockbf;	uint i; 	ARGBEGIN{	case 'f': // filename		fn = strdup(EARGF(usage()));		break;	case 'o': // offset		offset = atoi(EARGF(usage()));		break;	case 'n':		nblocks = atoi(EARGF(usage()));		break;	case 'b':		bsize = atoi(EARGF(usage()));		break;	case 'h':	default:		usage();	}ARGEND;	if(!fn)		usage();	fd = open(fn, OREAD);	if(fd < 0){		perror(nil);		exits("open");	}	blockbf = mallocz(bsize, 1);	if(!blockbf){		perror(nil);		exits("malloc");	}	print("dumping %ud blocks at %ulld from %s\n", nblocks, offset, fn);	for(i = 0; i < nblocks; i++){		if(pread(fd, blockbf, bsize, (offset+i)*bsize) < bsize){			fprint(2, "error: short read: %r\n");			exits("short read");		}		print("block %ulld (size = %ud) {\n", offset+i, bsize);		printblock(blockbf, bsize);		print("\n}\n\n");		memset(blockbf, 0, bsize);	}	close(fd);	free(blockbf);	free(fn);	exits(nil);}