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/*
* ROMFS file system, Linux implementation
*
* Copyright (C) 1997-1999 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
* Jun 1997 2.1.43+ changes
* Proper page locking in readpage
* Changed to work with 2.1.45+ fs
* Jul 1997 Fixed follow_link
* 2.1.47
* lookup shouldn't return -ENOENT
* from Horst von Brand:
* fail on wrong checksum
* double unlock_super was possible
* correct namelen for statfs
* spotted by Bill Hawes:
* readlink shouldn't iput()
* Jun 1998 2.1.106 from Avery Pennarun: glibc scandir()
* exposed a problem in readdir
* 2.1.107 code-freeze spellchecker run
* Aug 1998 2.1.118+ VFS changes
* Sep 1998 2.1.122 another VFS change (follow_link)
* Apr 1999 2.2.7 no more EBADF checking in
* lookup/readdir, use ERR_PTR
* Jun 1999 2.3.6 d_alloc_root use changed
* 2.3.9 clean up usage of ENOENT/negative
* dentries in lookup
* clean up page flags setting
* (error, uptodate, locking) in
* in readpage
* use init_special_inode for
* fifos/sockets (and streamline) in
* read_inode, fix _ops table order
* Aug 1999 2.3.16 __initfunc() => __init change
* Oct 1999 2.3.24 page->owner hack obsoleted
* Nov 1999 2.3.27 2.3.25+ page->offset => index change
*/
/* todo:
* - see Documentation/filesystems/romfs.txt
* - use allocated, not stack memory for file names?
* - considering write access...
* - network (tftp) files?
* - merge back some _op tables
*/
/*
* Sorry about some optimizations and for some goto's. I just wanted
* to squeeze some more bytes out of this code.. :)
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/romfs_fs.h>
#include <linux/fs.h>
#include <linux/locks.h>
#include <linux/init.h>
#include <linux/smp_lock.h>
#include <asm/uaccess.h>
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;
/* I would parse the options here, but there are none.. :) */
set_blocksize(dev, ROMBSIZE);
s->s_blocksize = ROMBSIZE;
s->s_blocksize_bits = ROMBSBITS;
s->u.generic_sbp = (void *) 0;
s->s_maxbytes = 0xFFFFFFFF;
bh = sb_bread(s, 0);
if (!bh) {
/* XXX merge with other printk? */
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_t(int, sz, 512))) {
printk ("romfs: bad initial checksum on dev "
"%s.\n", kdevname(dev));
goto out;
}
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;
s->s_root = d_alloc_root(iget(s, sz));
if (!s->s_root)
goto outnobh;
/* Ehrhm; sorry.. :) And thanks to Hans-Joachim Widmaier :) */
if (0) {
out:
brelse(bh);
outnobh:
s = NULL;
}
return s;
}
/* That's simple too. */
static int
romfs_statfs(struct super_block *sb, struct statfs *buf)
{
buf->f_type = ROMFS_MAGIC;
buf->f_bsize = ROMBSIZE;
buf->f_bfree = buf->f_bavail = buf->f_ffree;
buf->f_blocks = (sb->u.romfs_sb.s_maxsize+ROMBSIZE-1)>>ROMBSBITS;
buf->f_namelen = ROMFS_MAXFN;
return 0;
}
/* some helper routines */
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 = sb_bread(i->i_sb, offset>>ROMBSBITS);
if (!bh)
return -1; /* error */
avail = ROMBSIZE - (offset & ROMBMASK);
maxsize = min_t(unsigned long, 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 = sb_bread(i->i_sb, offset>>ROMBSBITS);
if (!bh)
return -1;
maxsize = min_t(unsigned long, 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 = sb_bread(i->i_sb, offset>>ROMBSBITS);
if (!bh)
return -1; /* error */
avail = ROMBSIZE - (offset & ROMBMASK);
maxsize = min_t(unsigned long, 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 = sb_bread(i->i_sb, offset>>ROMBSBITS);
if (!bh)
return -1;
maxsize = min_t(unsigned long, count - res, ROMBSIZE);
memcpy(dest, bh->b_data, maxsize);
brelse(bh);
res += maxsize;
}
return res;
}
static unsigned char romfs_dtype_table[] = {
DT_UNKNOWN, DT_DIR, DT_REG, DT_LNK, DT_BLK, DT_CHR, DT_SOCK, DT_FIFO
};
static int
romfs_readdir(struct file *filp, void *dirent, filldir_t filldir)
{
struct inode *i = filp->f_dentry->d_inode;
struct romfs_inode ri;
unsigned long offset, maxoff;
int j, ino, nextfh;
int stored = 0;
char fsname[ROMFS_MAXFN]; /* XXX dynamic? */
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 = maxoff;
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,
romfs_dtype_table[nextfh & ROMFH_TYPE]) < 0) {
return stored;
}
stored++;
offset = nextfh & ROMFH_MASK;
}
}
static struct dentry *
romfs_lookup(struct inode *dir, struct dentry *dentry)
{
unsigned long offset, maxoff;
int fslen, res;
struct inode *inode;
char fsname[ROMFS_MAXFN]; /* XXX dynamic? */
struct romfs_inode ri;
const char *name; /* got from dentry */
int len;
res = -EACCES; /* placeholder for "no data here" */
offset = dir->i_ino & ROMFH_MASK;
if (romfs_copyfrom(dir, &ri, offset, ROMFH_SIZE) <= 0)
goto out;
maxoff = dir->i_sb->u.romfs_sb.s_maxsize;
offset = ntohl(ri.spec) & ROMFH_MASK;
/* OK, now find the file whose name is in "dentry" in the
* directory specified by "dir". */
name = dentry->d_name.name;
len = dentry->d_name.len;
for(;;) {
if (!offset || offset >= maxoff)
goto out0;
if (romfs_copyfrom(dir, &ri, offset, ROMFH_SIZE) <= 0)
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;
if ((inode = iget(dir->i_sb, offset)))
goto outi;
/*
* it's a bit funky, _lookup needs to return an error code
* (negative) or a NULL, both as a dentry. ENOENT should not
* be returned, instead we need to create a negative dentry by
* d_add(dentry, NULL); and return 0 as no error.
* (Although as I see, it only matters on writable file
* systems).
*/
out0: inode = NULL;
outi: res = 0;
d_add (dentry, inode);
out: return ERR_PTR(res);
}
/*
* Ok, we do readpage, to be able to execute programs. Unfortunately,
* we can't use bmap, since we may have looser alignments.
*/
static int
romfs_readpage(struct file *file, struct page * page)
{
struct inode *inode = page->mapping->host;
unsigned long offset, avail, readlen;
void *buf;
int result = -EIO;
page_cache_get(page);
lock_kernel();
buf = kmap(page);
if (!buf)
goto err_out;
/* 32 bit warning -- but not for us :) */
offset = page->index << PAGE_CACHE_SHIFT;
if (offset < inode->i_size) {
avail = inode->i_size-offset;
readlen = min_t(unsigned long, avail, PAGE_SIZE);
if (romfs_copyfrom(inode, buf, inode->u.romfs_i.i_dataoffset+offset, readlen) == readlen) {
if (readlen < PAGE_SIZE) {
memset(buf + readlen,0,PAGE_SIZE-readlen);
}
SetPageUptodate(page);
result = 0;
}
}
if (result) {
memset(buf, 0, PAGE_SIZE);
SetPageError(page);
}
flush_dcache_page(page);
UnlockPage(page);
kunmap(page);
err_out:
page_cache_release(page);
unlock_kernel();
return result;
}
/* Mapping from our types to the kernel */
static struct address_space_operations romfs_aops = {
readpage: romfs_readpage
};
static struct file_operations romfs_dir_operations = {
read: generic_read_dir,
readdir: romfs_readdir,
};
static struct inode_operations romfs_dir_inode_operations = {
lookup: romfs_lookup,
};
static mode_t romfs_modemap[] =
{
0, S_IFDIR+0644, S_IFREG+0644, S_IFLNK+0777,
S_IFBLK+0600, S_IFCHR+0600, S_IFSOCK+0644, S_IFIFO+0644
};
static void
romfs_read_inode(struct inode *i)
{
int nextfh, ino;
struct romfs_inode ri;
ino = i->i_ino & ROMFH_MASK;
i->i_mode = 0;
/* 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;
}
/* XXX: do romfs_checksum here too (with name) */
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;
/* 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 = romfs_modemap[nextfh & ROMFH_TYPE];
/* only "normal" files have ops */
switch (nextfh & ROMFH_TYPE) {
case 1:
i->i_size = i->u.romfs_i.i_metasize;
i->i_op = &romfs_dir_inode_operations;
i->i_fop = &romfs_dir_operations;
if (nextfh & ROMFH_EXEC)
ino |= S_IXUGO;
i->i_mode = ino;
break;
case 2:
i->i_fop = &generic_ro_fops;
i->i_data.a_ops = &romfs_aops;
if (nextfh & ROMFH_EXEC)
ino |= S_IXUGO;
i->i_mode = ino;
break;
case 3:
i->i_op = &page_symlink_inode_operations;
i->i_data.a_ops = &romfs_aops;
i->i_mode = ino | S_IRWXUGO;
break;
default:
/* depending on MBZ for sock/fifos */
nextfh = ntohl(ri.spec);
nextfh = kdev_t_to_nr(MKDEV(nextfh>>16,nextfh&0xffff));
init_special_inode(i, ino, nextfh);
}
}
static struct super_operations romfs_ops = {
read_inode: romfs_read_inode,
statfs: romfs_statfs,
};
static DECLARE_FSTYPE_DEV(romfs_fs_type, "romfs", romfs_read_super);
static int __init init_romfs_fs(void)
{
return register_filesystem(&romfs_fs_type);
}
static void __exit exit_romfs_fs(void)
{
unregister_filesystem(&romfs_fs_type);
}
/* Yes, works even as a module... :) */
EXPORT_NO_SYMBOLS;
module_init(init_romfs_fs)
module_exit(exit_romfs_fs)
MODULE_LICENSE("GPL");
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