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DEFINITIONS
This source file includes following definitions.
- romfs_maxsize
- ROMFS_I
- romfs_checksum
- romfs_fill_super
- romfs_statfs
- romfs_strnlen
- romfs_copyfrom
- romfs_readdir
- romfs_lookup
- romfs_readpage
- romfs_iget
- romfs_alloc_inode
- romfs_destroy_inode
- init_once
- init_inodecache
- destroy_inodecache
- romfs_remount
- romfs_get_sb
- init_romfs_fs
- exit_romfs_fs
/*
* 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/init.h>
#include <linux/pagemap.h>
#include <linux/smp_lock.h>
#include <linux/buffer_head.h>
#include <linux/vfs.h>
#include <asm/uaccess.h>
struct romfs_inode_info {
unsigned long i_metasize; /* size of non-data area */
unsigned long i_dataoffset; /* from the start of fs */
struct inode vfs_inode;
};
static struct inode *romfs_iget(struct super_block *, unsigned long);
/* instead of private superblock data */
static inline unsigned long romfs_maxsize(struct super_block *sb)
{
return (unsigned long)sb->s_fs_info;
}
static inline struct romfs_inode_info *ROMFS_I(struct inode *inode)
{
return container_of(inode, struct romfs_inode_info, vfs_inode);
}
static __u32
romfs_checksum(void *data, int size)
{
__u32 sum;
__be32 *ptr;
sum = 0; ptr = data;
size>>=2;
while (size>0) {
sum += be32_to_cpu(*ptr++);
size--;
}
return sum;
}
static const struct super_operations romfs_ops;
static int romfs_fill_super(struct super_block *s, void *data, int silent)
{
struct buffer_head *bh;
struct romfs_super_block *rsb;
struct inode *root;
int sz, ret = -EINVAL;
/* I would parse the options here, but there are none.. :) */
sb_set_blocksize(s, ROMBSIZE);
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 = be32_to_cpu(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", s->s_id);
goto out;
}
if (romfs_checksum(rsb, min_t(int, sz, 512))) {
printk ("romfs: bad initial checksum on dev "
"%s.\n", s->s_id);
goto out;
}
s->s_magic = ROMFS_MAGIC;
s->s_fs_info = (void *)(long)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;
s->s_op = &romfs_ops;
root = romfs_iget(s, sz);
if (IS_ERR(root)) {
ret = PTR_ERR(root);
goto out;
}
ret = -ENOMEM;
s->s_root = d_alloc_root(root);
if (!s->s_root)
goto outiput;
brelse(bh);
return 0;
outiput:
iput(root);
out:
brelse(bh);
outnobh:
return ret;
}
/* That's simple too. */
static int
romfs_statfs(struct dentry *dentry, struct kstatfs *buf)
{
buf->f_type = ROMFS_MAGIC;
buf->f_bsize = ROMBSIZE;
buf->f_bfree = buf->f_bavail = buf->f_ffree;
buf->f_blocks = (romfs_maxsize(dentry->d_sb)+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 = romfs_maxsize(i->i_sb);
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 = romfs_maxsize(i->i_sb);
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_path.dentry->d_inode;
struct romfs_inode ri;
unsigned long offset, maxoff;
int j, ino, nextfh;
int stored = 0;
char fsname[ROMFS_MAXFN]; /* XXX dynamic? */
lock_kernel();
maxoff = romfs_maxsize(i->i_sb);
offset = filp->f_pos;
if (!offset) {
offset = i->i_ino & ROMFH_MASK;
if (romfs_copyfrom(i, &ri, offset, ROMFH_SIZE) <= 0)
goto out;
offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
}
/* Not really failsafe, but we are read-only... */
for(;;) {
if (!offset || offset >= maxoff) {
offset = maxoff;
filp->f_pos = offset;
goto out;
}
filp->f_pos = offset;
/* Fetch inode info */
if (romfs_copyfrom(i, &ri, offset, ROMFH_SIZE) <= 0)
goto out;
j = romfs_strnlen(i, offset+ROMFH_SIZE, sizeof(fsname)-1);
if (j < 0)
goto out;
fsname[j]=0;
romfs_copyfrom(i, fsname, offset+ROMFH_SIZE, j);
ino = offset;
nextfh = be32_to_cpu(ri.next);
if ((nextfh & ROMFH_TYPE) == ROMFH_HRD)
ino = be32_to_cpu(ri.spec);
if (filldir(dirent, fsname, j, offset, ino,
romfs_dtype_table[nextfh & ROMFH_TYPE]) < 0) {
goto out;
}
stored++;
offset = nextfh & ROMFH_MASK;
}
out:
unlock_kernel();
return stored;
}
static struct dentry *
romfs_lookup(struct inode *dir, struct dentry *dentry, struct nameidata *nd)
{
unsigned long offset, maxoff;
long res;
int fslen;
struct inode *inode = NULL;
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;
lock_kernel();
if (romfs_copyfrom(dir, &ri, offset, ROMFH_SIZE) <= 0)
goto error;
maxoff = romfs_maxsize(dir->i_sb);
offset = be32_to_cpu(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 success; /* negative success */
if (romfs_copyfrom(dir, &ri, offset, ROMFH_SIZE) <= 0)
goto error;
/* 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 = be32_to_cpu(ri.next) & ROMFH_MASK;
}
/* Hard link handling */
if ((be32_to_cpu(ri.next) & ROMFH_TYPE) == ROMFH_HRD)
offset = be32_to_cpu(ri.spec) & ROMFH_MASK;
inode = romfs_iget(dir->i_sb, offset);
if (IS_ERR(inode)) {
res = PTR_ERR(inode);
goto error;
}
success:
d_add(dentry, inode);
res = 0;
error:
unlock_kernel();
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;
loff_t offset, size;
unsigned long filled;
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_offset(page);
size = i_size_read(inode);
filled = 0;
result = 0;
if (offset < size) {
unsigned long readlen;
size -= offset;
readlen = size > PAGE_SIZE ? PAGE_SIZE : size;
filled = romfs_copyfrom(inode, buf, ROMFS_I(inode)->i_dataoffset+offset, readlen);
if (filled != readlen) {
SetPageError(page);
filled = 0;
result = -EIO;
}
}
if (filled < PAGE_SIZE)
memset(buf + filled, 0, PAGE_SIZE-filled);
if (!result)
SetPageUptodate(page);
flush_dcache_page(page);
unlock_page(page);
kunmap(page);
err_out:
page_cache_release(page);
unlock_kernel();
return result;
}
/* Mapping from our types to the kernel */
static const struct address_space_operations romfs_aops = {
.readpage = romfs_readpage
};
static const struct file_operations romfs_dir_operations = {
.read = generic_read_dir,
.readdir = romfs_readdir,
};
static const 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 struct inode *
romfs_iget(struct super_block *sb, unsigned long ino)
{
int nextfh;
struct romfs_inode ri;
struct inode *i;
ino &= ROMFH_MASK;
i = iget_locked(sb, ino);
if (!i)
return ERR_PTR(-ENOMEM);
if (!(i->i_state & I_NEW))
return i;
i->i_mode = 0;
/* Loop for finding the real hard link */
for(;;) {
if (romfs_copyfrom(i, &ri, ino, ROMFH_SIZE) <= 0) {
printk(KERN_ERR "romfs: read error for inode 0x%lx\n",
ino);
iget_failed(i);
return ERR_PTR(-EIO);
}
/* XXX: do romfs_checksum here too (with name) */
nextfh = be32_to_cpu(ri.next);
if ((nextfh & ROMFH_TYPE) != ROMFH_HRD)
break;
ino = be32_to_cpu(ri.spec) & ROMFH_MASK;
}
i->i_nlink = 1; /* Hard to decide.. */
i->i_size = be32_to_cpu(ri.size);
i->i_mtime.tv_sec = i->i_atime.tv_sec = i->i_ctime.tv_sec = 0;
i->i_mtime.tv_nsec = i->i_atime.tv_nsec = i->i_ctime.tv_nsec = 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;
ROMFS_I(i)->i_metasize = ino;
ROMFS_I(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 = ROMFS_I(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 = be32_to_cpu(ri.spec);
init_special_inode(i, ino,
MKDEV(nextfh>>16,nextfh&0xffff));
}
unlock_new_inode(i);
return i;
}
static struct kmem_cache * romfs_inode_cachep;
static struct inode *romfs_alloc_inode(struct super_block *sb)
{
struct romfs_inode_info *ei;
ei = kmem_cache_alloc(romfs_inode_cachep, GFP_KERNEL);
if (!ei)
return NULL;
return &ei->vfs_inode;
}
static void romfs_destroy_inode(struct inode *inode)
{
kmem_cache_free(romfs_inode_cachep, ROMFS_I(inode));
}
static void init_once(void *foo)
{
struct romfs_inode_info *ei = foo;
inode_init_once(&ei->vfs_inode);
}
static int init_inodecache(void)
{
romfs_inode_cachep = kmem_cache_create("romfs_inode_cache",
sizeof(struct romfs_inode_info),
0, (SLAB_RECLAIM_ACCOUNT|
SLAB_MEM_SPREAD),
init_once);
if (romfs_inode_cachep == NULL)
return -ENOMEM;
return 0;
}
static void destroy_inodecache(void)
{
kmem_cache_destroy(romfs_inode_cachep);
}
static int romfs_remount(struct super_block *sb, int *flags, char *data)
{
*flags |= MS_RDONLY;
return 0;
}
static const struct super_operations romfs_ops = {
.alloc_inode = romfs_alloc_inode,
.destroy_inode = romfs_destroy_inode,
.statfs = romfs_statfs,
.remount_fs = romfs_remount,
};
static int romfs_get_sb(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data, struct vfsmount *mnt)
{
return get_sb_bdev(fs_type, flags, dev_name, data, romfs_fill_super,
mnt);
}
static struct file_system_type romfs_fs_type = {
.owner = THIS_MODULE,
.name = "romfs",
.get_sb = romfs_get_sb,
.kill_sb = kill_block_super,
.fs_flags = FS_REQUIRES_DEV,
};
static int __init init_romfs_fs(void)
{
int err = init_inodecache();
if (err)
goto out1;
err = register_filesystem(&romfs_fs_type);
if (err)
goto out;
return 0;
out:
destroy_inodecache();
out1:
return err;
}
static void __exit exit_romfs_fs(void)
{
unregister_filesystem(&romfs_fs_type);
destroy_inodecache();
}
/* Yes, works even as a module... :) */
module_init(init_romfs_fs)
module_exit(exit_romfs_fs)
MODULE_LICENSE("GPL");