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#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include "types.h"
#include "param.h"
#include "fs.h"
int nblocks = 1009;
int ninodes = 100;
int fd;
struct superblock sb;
char zeroes[512];
uint freeblock;
void wsect(uint, void *);
void winode(uint, struct dinode *);
void rsect(uint sec, void *buf);
// convert to intel byte order
ushort
xshort(ushort x)
{
ushort y;
uchar *a = &y;
a[0] = x;
a[1] = x >> 8;
return y;
}
uint
xint(uint x)
{
uint y;
uchar *a = &y;
a[0] = x;
a[1] = x >> 8;
a[2] = x >> 16;
a[3] = x >> 24;
return y;
}
main(int argc, char *argv[])
{
int i;
struct dinode din;
char dbuf[512];
if(argc != 2){
fprintf(stderr, "Usage: mkfs fs.img\n");
exit(1);
}
if(sizeof(struct dinode) * IPB != 512){
fprintf(stderr, "sizeof(dinode) must divide 512\n");
exit(1);
}
fd = open(argv[1], O_RDWR|O_CREAT|O_TRUNC, 0666);
if(fd < 0){
perror(argv[1]);
exit(1);
}
sb.nblocks = xint(nblocks); // so whole disk is 1024 sectors
sb.ninodes = xint(ninodes);
freeblock = ninodes / IPB + 2;
for(i = 0; i < nblocks + (ninodes / IPB) + 3; i++)
wsect(i, zeroes);
wsect(1, &sb);
bzero(&din, sizeof(din));
din.type = xshort(T_DIR);
din.nlink = xshort(2);
din.size = xint(512);
din.addrs[0] = xint(freeblock++);
winode(1, &din);
bzero(dbuf, sizeof(dbuf));
((struct dirent *) dbuf)[0].inum = xshort(1);
strcpy(((struct dirent *) dbuf)[0].name, ".");
((struct dirent *) dbuf)[1].inum = xshort(1);
strcpy(((struct dirent *) dbuf)[1].name, "..");
wsect(din.addrs[0], dbuf);
exit(0);
}
void
wsect(uint sec, void *buf)
{
if(lseek(fd, sec * 512L, 0) != sec * 512L){
perror("lseek");
exit(1);
}
if(write(fd, buf, 512) != 512){
perror("write");
exit(1);
}
}
uint
i2b(uint inum)
{
return (inum / IPB) + 2;
}
void
winode(uint inum, struct dinode *ip)
{
char buf[512];
uint bn;
struct dinode *dip;
bn = i2b(inum);
rsect(bn, buf);
dip = ((struct dinode *) buf) + (inum % IPB);
*dip = *ip;
printf("bn %d off %d\n",
bn, (unsigned)dip - (unsigned) buf);
wsect(bn, buf);
}
void
rsect(uint sec, void *buf)
{
if(lseek(fd, sec * 512L, 0) != sec * 512L){
perror("lseek");
exit(1);
}
if(read(fd, buf, 512) != 512){
perror("read");
exit(1);
}
}
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