mkfs.c

早期freebsd实现

	{ ROOTINO, sizeof(struct direct), DT_DIR, 2, ".." },
	{ 0, DIRBLKSIZ, 0, 0, 0 },
};
struct odirect olost_found_dir[] = {
	{ LOSTFOUNDINO, sizeof(struct direct), 1, "." },
	{ ROOTINO, sizeof(struct direct), 2, ".." },
	{ 0, DIRBLKSIZ, 0, 0 },
};
#endif
char buf[MAXBSIZE];

fsinit(utime)
	time_t utime;
{
	int i;

	/*
	 * initialize the node
	 */
	node.di_atime.ts_sec = utime;
	node.di_mtime.ts_sec = utime;
	node.di_ctime.ts_sec = utime;
#ifdef LOSTDIR
	/*
	 * create the lost+found directory
	 */
	if (Oflag) {
		(void)makedir((struct direct *)olost_found_dir, 2);
		for (i = DIRBLKSIZ; i < sblock.fs_bsize; i += DIRBLKSIZ)
			bcopy(&olost_found_dir[2], &buf[i],
			    DIRSIZ(0, &olost_found_dir[2]));
	} else {
		(void)makedir(lost_found_dir, 2);
		for (i = DIRBLKSIZ; i < sblock.fs_bsize; i += DIRBLKSIZ)
			bcopy(&lost_found_dir[2], &buf[i],
			    DIRSIZ(0, &lost_found_dir[2]));
	}
	node.di_mode = IFDIR | UMASK;
	node.di_nlink = 2;
	node.di_size = sblock.fs_bsize;
	node.di_db[0] = alloc(node.di_size, node.di_mode);
	node.di_blocks = btodb(fragroundup(&sblock, node.di_size));
	wtfs(fsbtodb(&sblock, node.di_db[0]), node.di_size, buf);
	iput(&node, LOSTFOUNDINO);
#endif
	/*
	 * create the root directory
	 */
	if (mfs)
		node.di_mode = IFDIR | 01777;
	else
		node.di_mode = IFDIR | UMASK;
	node.di_nlink = PREDEFDIR;
	if (Oflag)
		node.di_size = makedir((struct direct *)oroot_dir, PREDEFDIR);
	else
		node.di_size = makedir(root_dir, PREDEFDIR);
	node.di_db[0] = alloc(sblock.fs_fsize, node.di_mode);
	node.di_blocks = btodb(fragroundup(&sblock, node.di_size));
	wtfs(fsbtodb(&sblock, node.di_db[0]), sblock.fs_fsize, buf);
	iput(&node, ROOTINO);
}

/*
 * construct a set of directory entries in "buf".
 * return size of directory.
 */
makedir(protodir, entries)
	register struct direct *protodir;
	int entries;
{
	char *cp;
	int i, spcleft;

	spcleft = DIRBLKSIZ;
	for (cp = buf, i = 0; i < entries - 1; i++) {
		protodir[i].d_reclen = DIRSIZ(0, &protodir[i]);
		bcopy(&protodir[i], cp, protodir[i].d_reclen);
		cp += protodir[i].d_reclen;
		spcleft -= protodir[i].d_reclen;
	}
	protodir[i].d_reclen = spcleft;
	bcopy(&protodir[i], cp, DIRSIZ(0, &protodir[i]));
	return (DIRBLKSIZ);
}

/*
 * allocate a block or frag
 */
daddr_t
alloc(size, mode)
	int size;
	int mode;
{
	int i, frag;
	daddr_t d, blkno;

	rdfs(fsbtodb(&sblock, cgtod(&sblock, 0)), sblock.fs_cgsize,
	    (char *)&acg);
	if (acg.cg_magic != CG_MAGIC) {
		printf("cg 0: bad magic number\n");
		return (0);
	}
	if (acg.cg_cs.cs_nbfree == 0) {
		printf("first cylinder group ran out of space\n");
		return (0);
	}
	for (d = 0; d < acg.cg_ndblk; d += sblock.fs_frag)
		if (isblock(&sblock, cg_blksfree(&acg), d / sblock.fs_frag))
			goto goth;
	printf("internal error: can't find block in cyl 0\n");
	return (0);
goth:
	blkno = fragstoblks(&sblock, d);
	clrblock(&sblock, cg_blksfree(&acg), blkno);
	clrbit(cg_clustersfree(&acg), blkno);
	acg.cg_cs.cs_nbfree--;
	sblock.fs_cstotal.cs_nbfree--;
	fscs[0].cs_nbfree--;
	if (mode & IFDIR) {
		acg.cg_cs.cs_ndir++;
		sblock.fs_cstotal.cs_ndir++;
		fscs[0].cs_ndir++;
	}
	cg_blktot(&acg)[cbtocylno(&sblock, d)]--;
	cg_blks(&sblock, &acg, cbtocylno(&sblock, d))[cbtorpos(&sblock, d)]--;
	if (size != sblock.fs_bsize) {
		frag = howmany(size, sblock.fs_fsize);
		fscs[0].cs_nffree += sblock.fs_frag - frag;
		sblock.fs_cstotal.cs_nffree += sblock.fs_frag - frag;
		acg.cg_cs.cs_nffree += sblock.fs_frag - frag;
		acg.cg_frsum[sblock.fs_frag - frag]++;
		for (i = frag; i < sblock.fs_frag; i++)
			setbit(cg_blksfree(&acg), d + i);
	}
	wtfs(fsbtodb(&sblock, cgtod(&sblock, 0)), sblock.fs_cgsize,
	    (char *)&acg);
	return (d);
}

/*
 * Allocate an inode on the disk
 */
iput(ip, ino)
	register struct dinode *ip;
	register ino_t ino;
{
	struct dinode buf[MAXINOPB];
	daddr_t d;
	int c;

	c = ino_to_cg(&sblock, ino);
	rdfs(fsbtodb(&sblock, cgtod(&sblock, 0)), sblock.fs_cgsize,
	    (char *)&acg);
	if (acg.cg_magic != CG_MAGIC) {
		printf("cg 0: bad magic number\n");
		exit(31);
	}
	acg.cg_cs.cs_nifree--;
	setbit(cg_inosused(&acg), ino);
	wtfs(fsbtodb(&sblock, cgtod(&sblock, 0)), sblock.fs_cgsize,
	    (char *)&acg);
	sblock.fs_cstotal.cs_nifree--;
	fscs[0].cs_nifree--;
	if (ino >= sblock.fs_ipg * sblock.fs_ncg) {
		printf("fsinit: inode value out of range (%d).\n", ino);
		exit(32);
	}
	d = fsbtodb(&sblock, ino_to_fsba(&sblock, ino));
	rdfs(d, sblock.fs_bsize, buf);
	buf[ino_to_fsbo(&sblock, ino)] = *ip;
	wtfs(d, sblock.fs_bsize, buf);
}

/*
 * Notify parent process that the filesystem has created itself successfully.
 */
void
started()
{

	exit(0);
}

/*
 * Replace libc function with one suited to our needs.
 */
caddr_t
malloc(size)
	register u_long size;
{
	char *base, *i;
	static u_long pgsz;
	struct rlimit rlp;

	if (pgsz == 0) {
		base = sbrk(0);
		pgsz = getpagesize() - 1;
		i = (char *)((u_long)(base + pgsz) &~ pgsz);
		base = sbrk(i - base);
		if (getrlimit(RLIMIT_DATA, &rlp) < 0)
			perror("getrlimit");
		rlp.rlim_cur = rlp.rlim_max;
		if (setrlimit(RLIMIT_DATA, &rlp) < 0)
			perror("setrlimit");
		memleft = rlp.rlim_max - (u_long)base;
	}
	size = (size + pgsz) &~ pgsz;
	if (size > memleft)
		size = memleft;
	memleft -= size;
	if (size == 0)
		return (0);
	return ((caddr_t)sbrk(size));
}

/*
 * Replace libc function with one suited to our needs.
 */
caddr_t
realloc(ptr, size)
	char *ptr;
	u_long size;
{
	void *p;

	if ((p = malloc(size)) == NULL)
		return (NULL);
	bcopy(ptr, p, size);
	free(ptr);
	return (p);
}

/*
 * Replace libc function with one suited to our needs.
 */
char *
calloc(size, numelm)
	u_long size, numelm;
{
	caddr_t base;

	size *= numelm;
	base = malloc(size);
	bzero(base, size);
	return (base);
}

/*
 * Replace libc function with one suited to our needs.
 */
free(ptr)
	char *ptr;
{
	
	/* do not worry about it for now */
}

/*
 * read a block from the file system
 */
rdfs(bno, size, bf)
	daddr_t bno;
	int size;
	char *bf;
{
	int n;

	if (mfs) {
		bcopy(membase + bno * sectorsize, bf, size);
		return;
	}
	if (lseek(fsi, (off_t)bno * sectorsize, 0) < 0) {
		printf("seek error: %ld\n", bno);
		perror("rdfs");
		exit(33);
	}
	n = read(fsi, bf, size);
	if (n != size) {
		printf("read error: %ld\n", bno);
		perror("rdfs");
		exit(34);
	}
}

/*
 * write a block to the file system
 */
wtfs(bno, size, bf)
	daddr_t bno;
	int size;
	char *bf;
{
	int n;

	if (mfs) {
		bcopy(bf, membase + bno * sectorsize, size);
		return;
	}
	if (Nflag)
		return;
	if (lseek(fso, (off_t)bno * sectorsize, SEEK_SET) < 0) {
		printf("seek error: %ld\n", bno);
		perror("wtfs");
		exit(35);
	}
	n = write(fso, bf, size);
	if (n != size) {
		printf("write error: %ld\n", bno);
		perror("wtfs");
		exit(36);
	}
}

/*
 * check if a block is available
 */
isblock(fs, cp, h)
	struct fs *fs;
	unsigned char *cp;
	int h;
{
	unsigned char mask;

	switch (fs->fs_frag) {
	case 8:
		return (cp[h] == 0xff);
	case 4:
		mask = 0x0f << ((h & 0x1) << 2);
		return ((cp[h >> 1] & mask) == mask);
	case 2:
		mask = 0x03 << ((h & 0x3) << 1);
		return ((cp[h >> 2] & mask) == mask);
	case 1:
		mask = 0x01 << (h & 0x7);
		return ((cp[h >> 3] & mask) == mask);
	default:
#ifdef STANDALONE
		printf("isblock bad fs_frag %d\n", fs->fs_frag);
#else
		fprintf(stderr, "isblock bad fs_frag %d\n", fs->fs_frag);
#endif
		return (0);
	}
}

/*
 * take a block out of the map
 */
clrblock(fs, cp, h)
	struct fs *fs;
	unsigned char *cp;
	int h;
{
	switch ((fs)->fs_frag) {
	case 8:
		cp[h] = 0;
		return;
	case 4:
		cp[h >> 1] &= ~(0x0f << ((h & 0x1) << 2));
		return;
	case 2:
		cp[h >> 2] &= ~(0x03 << ((h & 0x3) << 1));
		return;
	case 1:
		cp[h >> 3] &= ~(0x01 << (h & 0x7));
		return;
	default:
#ifdef STANDALONE
		printf("clrblock bad fs_frag %d\n", fs->fs_frag);
#else
		fprintf(stderr, "clrblock bad fs_frag %d\n", fs->fs_frag);
#endif
		return;
	}
}

/*
 * put a block into the map
 */
setblock(fs, cp, h)
	struct fs *fs;
	unsigned char *cp;
	int h;
{
	switch (fs->fs_frag) {
	case 8:
		cp[h] = 0xff;
		return;
	case 4:
		cp[h >> 1] |= (0x0f << ((h & 0x1) << 2));
		return;
	case 2:
		cp[h >> 2] |= (0x03 << ((h & 0x3) << 1));
		return;
	case 1:
		cp[h >> 3] |= (0x01 << (h & 0x7));
		return;
	default:
#ifdef STANDALONE
		printf("setblock bad fs_frag %d\n", fs->fs_frag);
#else
		fprintf(stderr, "setblock bad fs_frag %d\n", fs->fs_frag);
#endif
		return;
	}
}