include/linux/magic.h provides MAGIC numbers for various file systems. Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
485 lines
11 KiB
C
485 lines
11 KiB
C
/*
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* cramfs.c
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*
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* Copyright (C) 1999 Linus Torvalds
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*
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* Copyright (C) 2000-2002 Transmeta Corporation
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*
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* Copyright (C) 2003 Kai-Uwe Bloem,
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* Auerswald GmbH & Co KG, <linux-development@auerswald.de>
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* - adapted from the www.tuxbox.org barebox tree, added "ls" command
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License (Version 2) as
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* published by the Free Software Foundation.
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*
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* Compressed ROM filesystem for Linux.
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*
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* TODO:
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* add support for resolving symbolic links
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*/
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/*
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* These are the VFS interfaces to the compressed ROM filesystem.
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* The actual compression is based on zlib, see the other files.
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*/
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#include <common.h>
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#include <malloc.h>
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#include <driver.h>
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#include <init.h>
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#include <errno.h>
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#include <fs.h>
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#include <xfuncs.h>
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#include <asm/byteorder.h>
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#include <linux/stat.h>
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#include <linux/magic.h>
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#include <cramfs/cramfs_fs.h>
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/* These two macros may change in future, to provide better st_ino
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semantics. */
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#define CRAMINO(x) (CRAMFS_GET_OFFSET(x) ? CRAMFS_GET_OFFSET(x)<<2 : 1)
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#define OFFSET(x) ((x)->i_ino)
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struct cramfs_priv {
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struct cramfs_super super;
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int curr_base;
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char buf[4096];
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size_t curr_block_len;
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struct cdev *cdev;
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};
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struct cramfs_inode_info {
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struct cramfs_inode inode;
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unsigned long *block_ptrs;
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};
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static int cramfs_read_super(struct cramfs_priv *priv)
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{
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unsigned long root_offset;
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struct cramfs_super *super = &priv->super;
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struct cdev *cdev = priv->cdev;
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if (cdev_read(cdev, super, sizeof (struct cramfs_super), 0, 0) < sizeof (struct cramfs_super)) {
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printf("read superblock failed\n");
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return -EINVAL;
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}
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/* Do sanity checks on the superblock */
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if (super->magic != CRAMFS_32 (CRAMFS_MAGIC)) {
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/* check at 512 byte offset */
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if (cdev_read(cdev, super, sizeof (struct cramfs_super), 512, 0) < sizeof (struct cramfs_super)) {
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printf("read superblock failed\n");
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return -EINVAL;
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}
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if (super->magic != CRAMFS_32 (CRAMFS_MAGIC)) {
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printf ("cramfs: wrong magic\n");
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return -1;
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}
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}
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/* flags is reused several times, so swab it once */
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super->flags = CRAMFS_32 (super->flags);
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super->size = CRAMFS_32 (super->size);
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/* get feature flags first */
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if (super->flags & ~CRAMFS_SUPPORTED_FLAGS) {
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printf ("cramfs: unsupported filesystem features\n");
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return -1;
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}
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/* Check that the root inode is in a sane state */
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if (!S_ISDIR (CRAMFS_16 (super->root.mode))) {
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printf ("cramfs: root is not a directory\n");
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return -1;
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}
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root_offset = CRAMFS_GET_OFFSET (&(super->root)) << 2;
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if (root_offset == 0) {
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printf ("cramfs: empty filesystem");
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} else if (!(super->flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET) &&
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((root_offset != sizeof (struct cramfs_super)) &&
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(root_offset != 512 + sizeof (struct cramfs_super)))) {
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printf ("cramfs: bad root offset %lu\n", root_offset);
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return -1;
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}
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return 0;
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}
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static struct cramfs_inode_info *cramfs_get_inode(struct cramfs_priv *priv, unsigned long offset)
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{
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struct cramfs_inode_info *inodei = xmalloc(sizeof(*inodei));
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if (cdev_read(priv->cdev, &inodei->inode, sizeof(struct cramfs_inode), offset, 0) < 0) {
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free(inodei);
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return NULL;
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}
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return inodei;
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}
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static struct cramfs_inode_info *cramfs_resolve (struct cramfs_priv *priv, unsigned long offset,
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unsigned long size, int raw,
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char *filename)
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{
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unsigned long inodeoffset = 0, nextoffset;
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struct cramfs_inode_info *inodei = NULL, *ret;
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char *name = xmalloc(256);
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while (inodeoffset < size) {
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int namelen;
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inodei = cramfs_get_inode(priv, offset + inodeoffset);
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/*
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* Namelengths on disk are shifted by two
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* and the name padded out to 4-byte boundaries
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* with zeroes.
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*/
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namelen = CRAMFS_GET_NAMELEN (&inodei->inode) << 2;
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cdev_read(priv->cdev, name, namelen, offset + inodeoffset + sizeof (struct cramfs_inode), 0);
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nextoffset =
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inodeoffset + sizeof (struct cramfs_inode) + namelen;
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if (!strncmp (filename, name, namelen)) {
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char *p = strtok (NULL, "/");
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if (raw && (p == NULL || *p == '\0'))
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goto out1;
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if (S_ISDIR (CRAMFS_16 (inodei->inode.mode))) {
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ret = cramfs_resolve(priv,
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CRAMFS_GET_OFFSET(&inodei->inode) << 2,
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CRAMFS_24 (inodei->inode.size),
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raw, p);
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goto out;
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} else if (S_ISREG (CRAMFS_16 (inodei->inode.mode))) {
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goto out1;
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} else {
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printf ("%*.*s: unsupported file type (%x)\n",
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namelen, namelen, name,
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CRAMFS_16 (inodei->inode.mode));
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ret = NULL;
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goto out;
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}
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}
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free(inodei);
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inodeoffset = nextoffset;
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}
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free(name);
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return NULL;
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out1:
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ret = cramfs_get_inode(priv, offset + inodeoffset);
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out:
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free(inodei);
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free(name);
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return ret;
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}
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static int cramfs_fill_dirent (struct cramfs_priv *priv, unsigned long offset, struct dirent *d)
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{
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struct cramfs_inode_info *inodei = cramfs_get_inode(priv, offset);
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int namelen;
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if (!inodei)
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return -EINVAL;
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memset(d->d_name, 0, 256);
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/*
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* Namelengths on disk are shifted by two
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* and the name padded out to 4-byte boundaries
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* with zeroes.
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*/
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namelen = CRAMFS_GET_NAMELEN (&inodei->inode) << 2;
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cdev_read(priv->cdev, d->d_name, namelen, offset + sizeof(struct cramfs_inode), 0);
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free(inodei);
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return namelen;
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}
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struct cramfs_dir {
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unsigned long offset, size;
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unsigned long inodeoffset;
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DIR dir;
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};
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static DIR* cramfs_opendir(struct device_d *_dev, const char *filename)
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{
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struct cramfs_priv *priv = _dev->priv;
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char *f;
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struct cramfs_dir *dir = xzalloc(sizeof(struct cramfs_dir));
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dir->dir.priv = dir;
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if (strlen (filename) == 0 || !strcmp (filename, "/")) {
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/* Root directory. Use root inode in super block */
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dir->offset = CRAMFS_GET_OFFSET (&(priv->super.root)) << 2;
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dir->size = CRAMFS_24 (priv->super.root.size);
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} else {
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struct cramfs_inode_info *inodei;
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f = strdup(filename);
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/* Resolve the path */
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inodei = cramfs_resolve(priv,
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CRAMFS_GET_OFFSET (&(priv->super.root)) <<
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2, CRAMFS_24 (priv->super.root.size), 1,
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strtok (f, "/"));
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free(f);
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if (!inodei)
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goto err_free;
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/* Resolving was successful. Examine the inode */
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if (!S_ISDIR (CRAMFS_16 (inodei->inode.mode))) {
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/* It's not a directory */
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free(inodei);
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goto err_free;
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}
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dir->offset = CRAMFS_GET_OFFSET (&inodei->inode) << 2;
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dir->size = CRAMFS_24 (inodei->inode.size);
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free(inodei);
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}
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return &dir->dir;
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err_free:
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free(dir);
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return NULL;
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}
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static struct dirent* cramfs_readdir(struct device_d *_dev, DIR *_dir)
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{
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struct cramfs_priv *priv = _dev->priv;
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struct cramfs_dir *dir = _dir->priv;
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unsigned long nextoffset;
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/* List the given directory */
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if (dir->inodeoffset < dir->size) {
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nextoffset = cramfs_fill_dirent (priv, dir->offset + dir->inodeoffset, &_dir->d);
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dir->inodeoffset += sizeof (struct cramfs_inode) + nextoffset;
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return &_dir->d;
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}
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return NULL;
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}
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static int cramfs_closedir(struct device_d *dev, DIR *_dir)
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{
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struct cramfs_dir *dir = _dir->priv;
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free(dir);
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return 0;
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}
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static int cramfs_open(struct device_d *_dev, FILE *file, const char *filename)
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{
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struct cramfs_priv *priv = _dev->priv;
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struct cramfs_inode_info *inodei;
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char *f;
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f = strdup(filename);
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inodei = cramfs_resolve (priv,
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CRAMFS_GET_OFFSET (&(priv->super.root)) << 2,
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CRAMFS_24 (priv->super.root.size), 0,
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strtok (f, "/"));
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free(f);
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if (!inodei)
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return -ENOENT;
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file->priv = inodei;
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file->size = inodei->inode.size;
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inodei->block_ptrs = xzalloc(4096);
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cdev_read(priv->cdev, inodei->block_ptrs, 4096, CRAMFS_GET_OFFSET(&inodei->inode) << 2, 0);
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return 0;
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}
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static int cramfs_close(struct device_d *dev, FILE *file)
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{
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struct cramfs_inode_info *inodei = file->priv;
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free(inodei->block_ptrs);
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free(inodei);
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return 0;
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}
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static int cramfs_read(struct device_d *_dev, FILE *f, void *buf, size_t size)
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{
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struct cramfs_priv *priv = _dev->priv;
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struct cramfs_inode_info *inodei = f->priv;
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struct cramfs_inode *inode = &inodei->inode;
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unsigned int blocknr;
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int outsize = 0;
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unsigned long *block_ptrs = inodei->block_ptrs;
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int ofs = f->pos % 4096;
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static char cramfs_read_buf[4096];
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if (f->pos + size > inode->size)
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size = inode->size - f->pos;
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while (size) {
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unsigned long base;
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int copy;
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blocknr = (f->pos + outsize) >> 12;
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if (blocknr)
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base = CRAMFS_32 (block_ptrs[blocknr - 1]);
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else
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base = (CRAMFS_GET_OFFSET(inode) + (((CRAMFS_24 (inode->size)) + 4095) >> 12)) << 2;
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if (priv->curr_base < 0 || priv->curr_base != base) {
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cdev_read(priv->cdev, cramfs_read_buf, 4096, base, 0);
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priv->curr_block_len = cramfs_uncompress_block(priv->buf, 4096,
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cramfs_read_buf, 4096);
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if (priv->curr_block_len <= 0)
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break;
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priv->curr_base = base;
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}
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copy = min(priv->curr_block_len, size);
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memcpy(buf, priv->buf + ofs, copy);
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ofs = 0;
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outsize += copy;
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size -= copy;
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buf += copy;
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}
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return outsize;
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}
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static loff_t cramfs_lseek(struct device_d *dev, FILE *f, loff_t pos)
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{
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f->pos = pos;
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return f->pos;
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}
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static int cramfs_stat(struct device_d *_dev, const char *filename, struct stat *stat)
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{
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struct cramfs_priv *priv = _dev->priv;
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struct cramfs_inode_info *inodei;
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struct cramfs_inode *inode;
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char *f;
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f = strdup(filename);
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inodei = cramfs_resolve (priv,
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CRAMFS_GET_OFFSET (&(priv->super.root)) << 2,
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CRAMFS_24 (priv->super.root.size), 1,
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strtok (f, "/"));
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free(f);
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if (!inodei)
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return -ENOENT;
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inode = &inodei->inode;
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stat->st_mode = CRAMFS_16 (inode->mode);
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stat->st_size = CRAMFS_24 (inode->size);
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free(inodei);
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return 0;
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}
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#if 0
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static int cramfs_info (struct device_d *dev)
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{
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if (cramfs_read_super (dev))
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return 0;
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printf ("size: 0x%x (%u)\n", super.size, super.size);
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if (super.flags != 0) {
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printf ("flags:\n");
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if (super.flags & CRAMFS_FLAG_FSID_VERSION_2)
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printf ("\tFSID version 2\n");
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if (super.flags & CRAMFS_FLAG_SORTED_DIRS)
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printf ("\tsorted dirs\n");
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if (super.flags & CRAMFS_FLAG_HOLES)
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printf ("\tholes\n");
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if (super.flags & CRAMFS_FLAG_SHIFTED_ROOT_OFFSET)
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printf ("\tshifted root offset\n");
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}
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printf ("fsid:\n\tcrc: 0x%x\n\tedition: 0x%x\n",
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super.fsid.crc, super.fsid.edition);
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printf ("name: %16s\n", super.name);
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return 1;
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}
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#endif
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static int cramfs_probe(struct device_d *dev)
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{
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struct fs_device_d *fsdev;
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struct cramfs_priv *priv;
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int ret;
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fsdev = dev_to_fs_device(dev);
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priv = xmalloc(sizeof(struct cramfs_priv));
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dev->priv = priv;
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ret = fsdev_open_cdev(fsdev);
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if (ret)
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goto err_out;
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priv->cdev = fsdev->cdev;
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if (cramfs_read_super(priv)) {
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dev_info(dev, "no valid cramfs found\n");
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ret = -EINVAL;
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}
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priv->curr_base = -1;
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cramfs_uncompress_init ();
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return 0;
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err_out:
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free(priv);
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return ret;
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}
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static void cramfs_remove(struct device_d *dev)
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{
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struct cramfs_priv *priv = dev->priv;
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cramfs_uncompress_exit();
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free(priv);
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}
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static struct fs_driver_d cramfs_driver = {
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.open = cramfs_open,
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.close = cramfs_close,
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.read = cramfs_read,
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.lseek = cramfs_lseek,
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.opendir = cramfs_opendir,
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.readdir = cramfs_readdir,
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.closedir = cramfs_closedir,
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.stat = cramfs_stat,
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.drv = {
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.probe = cramfs_probe,
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.remove = cramfs_remove,
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.name = "cramfs",
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}
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};
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static int cramfs_init(void)
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{
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return register_fs_driver(&cramfs_driver);
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}
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device_initcall(cramfs_init);
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