patch-2.1.21 linux/fs/romfs/inode.c

• Lines: 667
• Date: Tue Jan 14 12:51:18 1997
• Orig file: v2.1.20/linux/fs/romfs/inode.c
• Orig date: Thu Jan 1 02:00:00 1970

diff -u --recursive --new-file v2.1.20/linux/fs/romfs/inode.c linux/fs/romfs/inode.c
@@ -0,0 +1,666 @@
+/*
+ * ROMFS file system, Linux implementation
+ *
+ * Copyright (C) 1997  Janos Farkas <chexum@shadow.banki.hu>
+ *
+ * Using parts of the minix filesystem
+ * Copyright (C) 1991, 1992  Linus Torvalds
+ *
+ * and parts of the affs filesystem additionally
+ * Copyright (C) 1993  Ray Burr
+ * Copyright (C) 1996  Hans-Joachim Widmaier
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ *
+ * Changes
+ *					Changed for 2.1.19 modules
+ *	Jan 1997			Initial release
+ */
+
+/* todo:
+ *	use malloced memory for file names?
+ *	considering write access...
+ *	network (tftp) files?
+ */
+
+/*
+ * Sorry about some optimizations and for some goto's.  I just wanted
+ * to squeeze some more bytes out of this code.. :)
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/malloc.h>
+#include <linux/romfs_fs.h>
+#include <linux/fs.h>
+#include <linux/locks.h>
+
+#include <asm/uaccess.h>
+
+static int inline min(int a, int b)
+{
+	return a<b ? a : b;
+}
+
+static __s32
+romfs_checksum(void *data, int size)
+{
+	__s32 sum, *ptr;
+
+	sum = 0; ptr = data;
+	size>>=2;
+	while (size>0) {
+		sum += ntohl(*ptr++);
+		size--;
+	}
+	return sum;
+}
+
+static struct super_operations romfs_ops;
+
+static struct super_block *
+romfs_read_super(struct super_block *s, void *data, int silent)
+{
+	struct buffer_head *bh;
+	kdev_t dev = s->s_dev;
+	struct romfs_super_block *rsb;
+	int sz;
+
+	MOD_INC_USE_COUNT;
+
+	/* I would parse the options, but there are none.. :) */
+
+	lock_super(s);
+	set_blocksize(dev, ROMBSIZE);
+	s->s_blocksize = ROMBSIZE;
+	s->s_blocksize_bits = ROMBSBITS;
+	bh = bread(dev, 0, ROMBSIZE);
+	if (!bh) {
+                printk ("romfs: unable to read superblock\n");
+		goto outnobh;
+	}
+
+	rsb = (struct romfs_super_block *)bh->b_data;
+	sz = ntohl(rsb->size);
+	if (rsb->word0 != ROMSB_WORD0 || rsb->word1 != ROMSB_WORD1
+	   || sz < ROMFH_SIZE) {
+		if (!silent)
+			printk ("VFS: Can't find a romfs filesystem on dev "
+				"%s.\n", kdevname(dev));
+		goto out;
+	}
+	if (romfs_checksum(rsb, min(sz,512))) {
+		printk ("romfs: bad initial checksum on dev "
+			"%s.\n", kdevname(dev));
+	}
+
+	s->s_magic = ROMFS_MAGIC;
+	s->u.romfs_sb.s_maxsize = sz;
+
+	s->s_flags |= MS_RDONLY;
+
+	/* Find the start of the fs */
+	sz = (ROMFH_SIZE +
+	      strnlen(rsb->name, ROMFS_MAXFN) + 1 + ROMFH_PAD)
+	     & ROMFH_MASK;
+
+	brelse(bh);
+
+	s->s_op	= &romfs_ops;
+
+	unlock_super(s);
+
+	if (!(s->s_mounted = iget(s, sz)))
+		goto outnobh;
+
+	/* Ehrhm; sorry.. :)  And thanks to Hans-Joachim Widmaier  :) */
+	if (0) {
+out:
+		brelse(bh);
+outnobh:
+		s->s_dev = 0;
+		unlock_super(s);
+		MOD_DEC_USE_COUNT;
+		s = NULL;
+	}
+
+	return s;
+}
+
+/* Nothing to do.. */
+
+static void
+romfs_put_super(struct super_block *sb)
+{
+	lock_super(sb);
+	sb->s_dev = 0;
+	unlock_super(sb);
+	MOD_DEC_USE_COUNT;
+	return;
+}
+
+
+/* That's simple too. */
+
+static void
+romfs_statfs(struct super_block *sb, struct statfs *buf, int bufsize)
+{
+	struct statfs tmp;
+
+	memset(&tmp, 0, sizeof(tmp));
+	tmp.f_type = ROMFS_MAGIC;
+	tmp.f_bsize = ROMBSIZE;
+	tmp.f_blocks = (sb->u.romfs_sb.s_maxsize+ROMBSIZE-1)>>ROMBSBITS;
+	copy_to_user(buf, &tmp, bufsize);
+}
+
+static int
+romfs_strnlen(struct inode *i, unsigned long offset, unsigned long count)
+{
+	struct buffer_head *bh;
+	unsigned long avail, maxsize, res;
+
+	maxsize = i->i_sb->u.romfs_sb.s_maxsize;
+	if (offset >= maxsize)
+		return -1;
+
+	/* strnlen is almost always valid */
+	if (count > maxsize || offset+count > maxsize)
+		count = maxsize-offset;
+
+	bh = bread(i->i_dev, offset>>ROMBSBITS, ROMBSIZE);
+	if (!bh)
+		return -1;		/* error */
+
+	avail = ROMBSIZE - (offset & ROMBMASK);
+	maxsize = min(count, avail);
+	res = strnlen(((char *)bh->b_data)+(offset&ROMBMASK), maxsize);
+	brelse(bh);
+
+	if (res < maxsize)
+		return res;		/* found all of it */
+
+	while (res < count) {
+		offset += maxsize;
+
+		bh = bread(i->i_dev, offset>>ROMBSBITS, ROMBSIZE);
+		if (!bh)
+			return -1;
+		maxsize = min(count-res, ROMBSIZE);
+		avail = strnlen(bh->b_data, maxsize);
+		res += avail;
+		brelse(bh);
+		if (avail < maxsize)
+			return res;
+	}
+	return res;
+}
+
+static int
+romfs_copyfrom(struct inode *i, void *dest, unsigned long offset, unsigned long count)
+{
+	struct buffer_head *bh;
+	unsigned long avail, maxsize, res;
+
+	maxsize = i->i_sb->u.romfs_sb.s_maxsize;
+	if (offset >= maxsize || count > maxsize || offset+count>maxsize)
+		return -1;
+
+	bh = bread(i->i_dev, offset>>ROMBSBITS, ROMBSIZE);
+	if (!bh)
+		return -1;		/* error */
+
+	avail = ROMBSIZE - (offset & ROMBMASK);
+	maxsize = min(count, avail);
+	memcpy(dest, ((char *)bh->b_data) + (offset & ROMBMASK), maxsize);
+	brelse(bh);
+
+	res = maxsize;			/* all of it */
+
+	while (res < count) {
+		offset += maxsize;
+		dest += maxsize;
+
+		bh = bread(i->i_dev, offset>>ROMBSBITS, ROMBSIZE);
+		if (!bh)
+			return -1;
+		maxsize = min(count-res, ROMBSIZE);
+		memcpy(dest, bh->b_data, maxsize);
+		brelse(bh);
+		res += maxsize;
+	}
+	return res;
+}
+
+/* Directory operations */
+
+static int
+romfs_readdir(struct inode *i, struct file *filp, void *dirent, filldir_t filldir)
+{
+	struct romfs_inode ri;
+	unsigned long offset, maxoff;
+	int j, ino, nextfh;
+	int stored = 0;
+	char fsname[ROMFS_MAXFN];	/* XXX dynamic? */
+
+	if (!i || !S_ISDIR(i->i_mode))
+		return -EBADF;
+
+	maxoff = i->i_sb->u.romfs_sb.s_maxsize;
+
+	offset = filp->f_pos;
+	if (!offset) {
+		offset = i->i_ino & ROMFH_MASK;
+		if (romfs_copyfrom(i, &ri, offset, ROMFH_SIZE) <= 0)
+			return stored;
+		offset = ntohl(ri.spec) & ROMFH_MASK;
+	}
+
+	/* Not really failsafe, but we are read-only... */
+	for(;;) {
+		if (!offset || offset >= maxoff) {
+			offset = 0xffffffff;
+			filp->f_pos = offset;
+			return stored;
+		}
+		filp->f_pos = offset;
+
+		/* Fetch inode info */
+		if (romfs_copyfrom(i, &ri, offset, ROMFH_SIZE) <= 0)
+			return stored;
+
+		j = romfs_strnlen(i, offset+ROMFH_SIZE, sizeof(fsname)-1);
+		if (j < 0)
+			return stored;
+
+		fsname[j]=0;
+		romfs_copyfrom(i, fsname, offset+ROMFH_SIZE, j);
+
+		ino = offset;
+		nextfh = ntohl(ri.next);
+		if ((nextfh & ROMFH_TYPE) == ROMFH_HRD)
+			ino = ntohl(ri.spec);
+		if (filldir(dirent, fsname, j, offset, ino) < 0) {
+			return stored;
+		}
+		stored++;
+		offset = nextfh & ROMFH_MASK;
+	}
+}
+
+static int
+romfs_lookup(struct inode *dir, const char *name, int len, struct inode **result)
+{
+	unsigned long offset, maxoff;
+	int fslen, res;
+	char fsname[ROMFS_MAXFN];	/* XXX dynamic? */
+	struct romfs_inode ri;
+
+	*result = NULL;
+	if (!dir || !S_ISDIR(dir->i_mode)) {
+		res = -EBADF;
+		goto out;
+	}
+
+	offset = dir->i_ino & ROMFH_MASK;
+	if (romfs_copyfrom(dir, &ri, offset, ROMFH_SIZE) <= 0) {
+		res = -ENOENT;
+		goto out;
+	}
+
+	maxoff = dir->i_sb->u.romfs_sb.s_maxsize;
+	offset = ntohl(ri.spec) & ROMFH_MASK;
+
+	for(;;) {
+		if (!offset || offset >= maxoff
+		    || romfs_copyfrom(dir, &ri, offset, ROMFH_SIZE) <= 0) {
+			res = -ENOENT;
+			goto out;
+		}
+
+		/* try to match the first 16 bytes of name */
+		fslen = romfs_strnlen(dir, offset+ROMFH_SIZE, ROMFH_SIZE);
+		if (len < ROMFH_SIZE) {
+			if (len == fslen) {
+				/* both are shorter, and same size */
+				romfs_copyfrom(dir, fsname, offset+ROMFH_SIZE, len+1);
+				if (strncmp (name, fsname, len) == 0)
+					break;
+			}
+		} else if (fslen >= ROMFH_SIZE) {
+			/* both are longer; XXX optimize max size */
+			fslen = romfs_strnlen(dir, offset+ROMFH_SIZE, sizeof(fsname)-1);
+			if (len == fslen) {
+				romfs_copyfrom(dir, fsname, offset+ROMFH_SIZE, len+1);
+				if (strncmp(name, fsname, len) == 0)
+					break;
+			}
+		}
+		/* next entry */
+		offset = ntohl(ri.next) & ROMFH_MASK;
+	}
+
+	/* Hard link handling */
+	if ((ntohl(ri.next) & ROMFH_TYPE) == ROMFH_HRD)
+		offset = ntohl(ri.spec) & ROMFH_MASK;
+
+	res = 0;
+	if (!(*result = iget(dir->i_sb, offset)))
+		res = -EACCES;
+
+out:
+	iput(dir);
+	return res;
+}
+
+/*
+ * Ok, we do readpage, to be able to execute programs.  Unfortunately,
+ * bmap is not applicable, since we have looser alignments.
+ *
+ * XXX I'm not quite sure that I need to muck around the PG_xx bits..
+ */
+
+static int
+romfs_readpage(struct inode * inode, struct page * page)
+{
+	unsigned long buf;
+	unsigned long offset, avail, readlen;
+	int result = -EIO;
+
+	buf = page_address(page);
+	page->count++;
+	offset = page->offset;
+	if (offset < inode->i_size) {
+		avail = inode->i_size-offset;
+		readlen = min(avail, PAGE_SIZE);
+		if (romfs_copyfrom(inode, (void *)buf, inode->u.romfs_i.i_dataoffset+offset, readlen) == readlen) {
+			if (readlen < PAGE_SIZE) {
+				memset((void *)(buf+readlen),0,PAGE_SIZE-readlen);
+			}
+			result = 0;
+			set_bit(PG_uptodate, &page->flags);
+		} else {
+			memset((void *)buf, 0, PAGE_SIZE);
+		}
+	}
+	free_page(buf);
+	return result;
+}
+
+static int
+romfs_readlink(struct inode *inode, char *buffer, int len)
+{
+	int mylen;
+	char buf[ROMFS_MAXFN];		/* XXX dynamic */
+
+	if (!inode || !S_ISLNK(inode->i_mode)) {
+		mylen = -EBADF;
+		goto out;
+	}
+
+	mylen = min(sizeof(buf), inode->i_size);
+
+	if (romfs_copyfrom(inode, buf, inode->u.romfs_i.i_dataoffset, mylen) <= 0) {
+		mylen = -EIO;
+		goto out;
+	}
+	copy_to_user(buffer, buf, mylen);
+
+out:
+	iput(inode);
+	return mylen;
+}
+
+static int
+romfs_follow_link(struct inode *dir, struct inode *inode,
+	int flag, int mode, struct inode **res_inode)
+{
+	int error, len;
+	char *buf;
+
+	*res_inode = NULL;
+	if (!dir) {
+		dir = current->fs->root;
+		dir->i_count++;
+	}
+
+	if (!inode) {
+		iput(dir);
+		return -ENOENT;
+	}
+	if (!S_ISLNK(inode->i_mode)) {
+		*res_inode = inode;
+		iput(dir);
+		return 0;
+	}
+	if (current->link_count > 5) {
+		iput(inode);
+		iput(dir);
+		return -ELOOP;
+	}
+
+	/* Eek. Short enough. */
+	len = inode->i_size;
+	if (!(buf = kmalloc(len+1, GFP_KERNEL))) {
+		iput(inode);
+		iput(dir);
+		/* correct?  spin? */
+		return -EAGAIN;
+	}
+	error = romfs_copyfrom(inode, buf, inode->u.romfs_i.i_dataoffset, len);
+	if (error != len) {
+		iput(inode);
+		iput(dir);
+		error = -EIO;
+	} else {
+		iput(inode);
+		buf[len] = 0;
+		current->link_count++;
+		error = open_namei(buf, flag, mode, res_inode, dir);
+		current->link_count--;
+	}
+
+	kfree(buf);
+	return error;
+}
+
+/* Mapping from our types to the kernel */
+
+static struct file_operations romfs_file_operations = {
+	NULL,			/* lseek - default */
+        generic_file_read,	/* read */
+	NULL,			/* write - bad */
+	NULL,			/* readdir */
+	NULL,			/* select - default */
+	NULL,			/* ioctl */
+	generic_file_mmap,	/* mmap */
+	NULL,			/* open */
+	NULL,			/* release */
+	NULL,			/* fsync */
+	NULL,			/* fasync */
+	NULL,			/* check_media_change */
+	NULL			/* revalidate */
+};
+
+static struct inode_operations romfs_file_inode_operations = {
+	&romfs_file_operations,
+	NULL,			/* create */
+	NULL,			/* lookup */
+	NULL,			/* link */
+	NULL,			/* unlink */
+	NULL,			/* symlink */
+	NULL,			/* mkdir */
+	NULL,			/* rmdir */
+	NULL,			/* mknod */
+	NULL,			/* rename */
+	NULL,			/* readlink */
+	NULL,			/* follow_link */
+	romfs_readpage,		/* readpage */
+	NULL,			/* writepage */
+	NULL,			/* bmap -- not really */
+	NULL,			/* truncate */
+	NULL,			/* permission */
+	NULL,			/* smap */
+};
+
+static struct file_operations romfs_dir_operations = {
+	NULL,			/* lseek - default */
+        NULL,			/* read */
+	NULL,			/* write - bad */
+	romfs_readdir,		/* readdir */
+	NULL,			/* select - default */
+	NULL,			/* ioctl */
+	NULL,			/* mmap */
+	NULL,			/* open */
+	NULL,			/* release */
+	NULL,			/* fsync */
+	NULL,			/* fasync */
+	NULL,			/* check_media_change */
+	NULL			/* revalidate */
+};
+
+/* Merged dir/symlink op table.  readdir/lookup/readlink/follow_link
+ * will protect from type mismatch.
+ */
+
+static struct inode_operations romfs_dirlink_inode_operations = {
+	&romfs_dir_operations,
+	NULL,			/* create */
+	romfs_lookup,		/* lookup */
+	NULL,			/* link */
+	NULL,			/* unlink */
+	NULL,			/* symlink */
+	NULL,			/* mkdir */
+	NULL,			/* rmdir */
+	NULL,			/* mknod */
+	NULL,			/* rename */
+	romfs_readlink,		/* readlink */
+	romfs_follow_link,	/* follow_link */
+	NULL,			/* readpage */
+	NULL,			/* writepage */
+	NULL,			/* bmap */
+	NULL,			/* truncate */
+	NULL,			/* permission */
+	NULL,			/* smap */
+};
+
+static mode_t romfs_modemap[] =
+{
+	0, S_IFDIR, S_IFREG, S_IFLNK+0777,
+	S_IFBLK, S_IFCHR, S_IFSOCK, S_IFIFO
+};
+
+static struct inode_operations *romfs_inoops[] =
+{
+	NULL,				/* hardlink, handled elsewhere */
+	&romfs_dirlink_inode_operations,
+	&romfs_file_inode_operations,
+	&romfs_dirlink_inode_operations,
+	&blkdev_inode_operations,	/* standard handlers */
+	&chrdev_inode_operations,
+	NULL,				/* socket */
+	NULL,				/* fifo */
+};
+
+static void
+romfs_read_inode(struct inode *i)
+{
+	int nextfh, ino;
+	struct romfs_inode ri;
+
+	i->i_op = NULL;
+
+	ino = i->i_ino & ROMFH_MASK;
+
+	/* Loop for finding the real hard link */
+	for(;;) {
+		if (romfs_copyfrom(i, &ri, ino, ROMFH_SIZE) <= 0) {
+			printk("romfs: read error for inode 0x%x\n", ino);
+			return;
+		}
+		nextfh = ntohl(ri.next);
+		if ((nextfh & ROMFH_TYPE) != ROMFH_HRD)
+			break;
+
+		ino = ntohl(ri.spec) & ROMFH_MASK;
+	}
+
+	i->i_nlink = 1;		/* Hard to decide.. */
+	i->i_size = ntohl(ri.size);
+	i->i_mtime = i->i_atime = i->i_ctime = 0;
+	i->i_uid = i->i_gid = 0;
+
+	i->i_op = romfs_inoops[nextfh & ROMFH_TYPE];
+
+	/* Precalculate the data offset */
+	ino = romfs_strnlen(i, ino+ROMFH_SIZE, ROMFS_MAXFN);
+	if (ino >= 0)
+		ino = ((ROMFH_SIZE+ino+1+ROMFH_PAD)&ROMFH_MASK);
+	else
+		ino = 0;
+	i->u.romfs_i.i_metasize = ino;
+	i->u.romfs_i.i_dataoffset = ino+(i->i_ino&ROMFH_MASK);
+
+	/* Compute permissions */
+	ino = S_IRUGO|S_IWUSR;
+	ino |= romfs_modemap[nextfh & ROMFH_TYPE];
+	if (nextfh & ROMFH_EXEC) {
+		ino |= S_IXUGO;
+	}
+	i->i_mode = ino;
+
+	if (S_ISFIFO(ino))
+		init_fifo(i);
+	else if (S_ISDIR(ino))
+		i->i_size = i->u.romfs_i.i_metasize;
+	else if (S_ISBLK(ino) || S_ISCHR(ino)) {
+		i->i_mode &= ~(S_IRWXG|S_IRWXO);
+		ino = ntohl(ri.spec);
+		i->i_rdev = MKDEV(ino>>16,ino&0xffff);
+	}
+}
+
+static struct super_operations romfs_ops = {
+	romfs_read_inode,	/* read inode */
+	NULL,			/* notify change */
+	NULL,			/* write inode */
+	NULL,			/* put inode */
+	romfs_put_super,	/* put super */
+	NULL,			/* write super */
+	romfs_statfs,		/* statfs */
+	NULL			/* remount */
+};
+
+static struct file_system_type romfs_fs_type = {
+	romfs_read_super, "romfs", 1, NULL
+};
+
+int
+init_romfs_fs(void)
+{
+	return register_filesystem(&romfs_fs_type);
+}
+
+#ifdef MODULE
+
+/* Yes, works even as a module... :) */
+
+EXPORT_NO_SYMBOLS;
+
+int
+init_module(void)
+{
+	return init_romfs_fs();
+}
+
+void
+cleanup_module(void)
+{
+	unregister_filesystem(&romfs_fs_type);
+}
+#endif