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capifs.c

/* $Id: capifs.c,v 1.1.2.3 2004/01/16 21:09:26 keil Exp $
 * 
 * Copyright 2000 by Carsten Paeth <calle@calle.de>
 *
 * Heavily based on devpts filesystem from H. Peter Anvin
 * 
 * This software may be used and distributed according to the terms
 * of the GNU General Public License, incorporated herein by reference.
 *
 */

#include <linux/fs.h>
#include <linux/mount.h>
#include <linux/namei.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/ctype.h>
#include <linux/sched.h>      /* current */

#include "capifs.h"

MODULE_DESCRIPTION("CAPI4Linux: /dev/capi/ filesystem");
MODULE_AUTHOR("Carsten Paeth");
MODULE_LICENSE("GPL");

/* ------------------------------------------------------------------ */

static char *revision = "$Revision: 1.1.2.3 $";

/* ------------------------------------------------------------------ */

#define CAPIFS_SUPER_MAGIC (('C'<<8)|'N')

static struct vfsmount *capifs_mnt;
static struct dentry *capifs_root;

static struct {
      int setuid;
      int setgid;
      uid_t   uid;
      gid_t   gid;
      umode_t mode;
} config = {.mode = 0600};

/* ------------------------------------------------------------------ */

static int capifs_remount(struct super_block *s, int *flags, char *data)
{
      int setuid = 0;
      int setgid = 0;
      uid_t uid = 0;
      gid_t gid = 0;
      umode_t mode = 0600;
      char *this_char;

      this_char = NULL;
      while ((this_char = strsep(&data, ",")) != NULL) {
            int n;
            char dummy;
            if (!*this_char)
                  continue;
            if (sscanf(this_char, "uid=%i%c", &n, &dummy) == 1) {
                  setuid = 1;
                  uid = n;
            } else if (sscanf(this_char, "gid=%i%c", &n, &dummy) == 1) {
                  setgid = 1;
                  gid = n;
            } else if (sscanf(this_char, "mode=%o%c", &n, &dummy) == 1)
                  mode = n & ~S_IFMT;
            else {
                  printk("capifs: called with bogus options\n");
                  return -EINVAL;
            }
      }
      config.setuid  = setuid;
      config.setgid  = setgid;
      config.uid     = uid;
      config.gid     = gid;
      config.mode    = mode;
      return 0;
}

static struct super_operations capifs_sops =
{
      .statfs           = simple_statfs,
      .remount_fs = capifs_remount,
};


static int
capifs_fill_super(struct super_block *s, void *data, int silent)
{
      struct inode * inode;

      s->s_blocksize = 1024;
      s->s_blocksize_bits = 10;
      s->s_magic = CAPIFS_SUPER_MAGIC;
      s->s_op = &capifs_sops;
      s->s_time_gran = 1;

      inode = new_inode(s);
      if (!inode)
            goto fail;
      inode->i_ino = 1;
      inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
      inode->i_blocks = 0;
      inode->i_uid = inode->i_gid = 0;
      inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
      inode->i_op = &simple_dir_inode_operations;
      inode->i_fop = &simple_dir_operations;
      inode->i_nlink = 2;

      capifs_root = s->s_root = d_alloc_root(inode);
      if (s->s_root)
            return 0;
      
      printk("capifs: get root dentry failed\n");
      iput(inode);
fail:
      return -ENOMEM;
}

static int capifs_get_sb(struct file_system_type *fs_type,
      int flags, const char *dev_name, void *data, struct vfsmount *mnt)
{
      return get_sb_single(fs_type, flags, data, capifs_fill_super, mnt);
}

static struct file_system_type capifs_fs_type = {
      .owner            = THIS_MODULE,
      .name       = "capifs",
      .get_sb           = capifs_get_sb,
      .kill_sb    = kill_anon_super,
};

static struct dentry *get_node(int num)
{
      char s[10];
      struct dentry *root = capifs_root;
      mutex_lock(&root->d_inode->i_mutex);
      return lookup_one_len(s, root, sprintf(s, "%d", num));
}

void capifs_new_ncci(unsigned int number, dev_t device)
{
      struct dentry *dentry;
      struct inode *inode = new_inode(capifs_mnt->mnt_sb);
      if (!inode)
            return;
      inode->i_ino = number+2;
      inode->i_uid = config.setuid ? config.uid : current->fsuid;
      inode->i_gid = config.setgid ? config.gid : current->fsgid;
      inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
      init_special_inode(inode, S_IFCHR|config.mode, device);
      //inode->i_op = &capifs_file_inode_operations;

      dentry = get_node(number);
      if (!IS_ERR(dentry) && !dentry->d_inode)
            d_instantiate(dentry, inode);
      mutex_unlock(&capifs_root->d_inode->i_mutex);
}

void capifs_free_ncci(unsigned int number)
{
      struct dentry *dentry = get_node(number);

      if (!IS_ERR(dentry)) {
            struct inode *inode = dentry->d_inode;
            if (inode) {
                  inode->i_nlink--;
                  d_delete(dentry);
                  dput(dentry);
            }
            dput(dentry);
      }
      mutex_unlock(&capifs_root->d_inode->i_mutex);
}

static int __init capifs_init(void)
{
      char rev[32];
      char *p;
      int err;

      if ((p = strchr(revision, ':')) != 0 && p[1]) {
            strlcpy(rev, p + 2, sizeof(rev));
            if ((p = strchr(rev, '$')) != 0 && p > rev)
               *(p-1) = 0;
      } else
            strcpy(rev, "1.0");

      err = register_filesystem(&capifs_fs_type);
      if (!err) {
            capifs_mnt = kern_mount(&capifs_fs_type);
            if (IS_ERR(capifs_mnt)) {
                  err = PTR_ERR(capifs_mnt);
                  unregister_filesystem(&capifs_fs_type);
            }
      }
      if (!err)
            printk(KERN_NOTICE "capifs: Rev %s\n", rev);
      return err;
}

static void __exit capifs_exit(void)
{
      unregister_filesystem(&capifs_fs_type);
      mntput(capifs_mnt);
}

EXPORT_SYMBOL(capifs_new_ncci);
EXPORT_SYMBOL(capifs_free_ncci);

module_init(capifs_init);
module_exit(capifs_exit);

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