linux/drivers/isdn/capi/capifs.c
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   1/* $Id: capifs.c,v 1.1.2.3 2004/01/16 21:09:26 keil Exp $
   2 * 
   3 * Copyright 2000 by Carsten Paeth <calle@calle.de>
   4 *
   5 * Heavily based on devpts filesystem from H. Peter Anvin
   6 * 
   7 * This software may be used and distributed according to the terms
   8 * of the GNU General Public License, incorporated herein by reference.
   9 *
  10 */
  11
  12#include <linux/fs.h>
  13#include <linux/mount.h>
  14#include <linux/namei.h>
  15#include <linux/module.h>
  16#include <linux/init.h>
  17#include <linux/ctype.h>
  18#include <linux/sched.h>        /* current */
  19
  20#include "capifs.h"
  21
  22MODULE_DESCRIPTION("CAPI4Linux: /dev/capi/ filesystem");
  23MODULE_AUTHOR("Carsten Paeth");
  24MODULE_LICENSE("GPL");
  25
  26/* ------------------------------------------------------------------ */
  27
  28static char *revision = "$Revision: 1.1.2.3 $";
  29
  30/* ------------------------------------------------------------------ */
  31
  32#define CAPIFS_SUPER_MAGIC (('C'<<8)|'N')
  33
  34static struct vfsmount *capifs_mnt;
  35static struct dentry *capifs_root;
  36
  37static struct {
  38        int setuid;
  39        int setgid;
  40        uid_t   uid;
  41        gid_t   gid;
  42        umode_t mode;
  43} config = {.mode = 0600};
  44
  45/* ------------------------------------------------------------------ */
  46
  47static int capifs_remount(struct super_block *s, int *flags, char *data)
  48{
  49        int setuid = 0;
  50        int setgid = 0;
  51        uid_t uid = 0;
  52        gid_t gid = 0;
  53        umode_t mode = 0600;
  54        char *this_char;
  55        char *new_opt = kstrdup(data, GFP_KERNEL);
  56
  57        this_char = NULL;
  58        while ((this_char = strsep(&data, ",")) != NULL) {
  59                int n;
  60                char dummy;
  61                if (!*this_char)
  62                        continue;
  63                if (sscanf(this_char, "uid=%i%c", &n, &dummy) == 1) {
  64                        setuid = 1;
  65                        uid = n;
  66                } else if (sscanf(this_char, "gid=%i%c", &n, &dummy) == 1) {
  67                        setgid = 1;
  68                        gid = n;
  69                } else if (sscanf(this_char, "mode=%o%c", &n, &dummy) == 1)
  70                        mode = n & ~S_IFMT;
  71                else {
  72                        kfree(new_opt);
  73                        printk("capifs: called with bogus options\n");
  74                        return -EINVAL;
  75                }
  76        }
  77
  78        kfree(s->s_options);
  79        s->s_options = new_opt;
  80
  81        config.setuid  = setuid;
  82        config.setgid  = setgid;
  83        config.uid     = uid;
  84        config.gid     = gid;
  85        config.mode    = mode;
  86
  87        return 0;
  88}
  89
  90static struct super_operations capifs_sops =
  91{
  92        .statfs         = simple_statfs,
  93        .remount_fs     = capifs_remount,
  94        .show_options   = generic_show_options,
  95};
  96
  97
  98static int
  99capifs_fill_super(struct super_block *s, void *data, int silent)
 100{
 101        struct inode * inode;
 102
 103        s->s_blocksize = 1024;
 104        s->s_blocksize_bits = 10;
 105        s->s_magic = CAPIFS_SUPER_MAGIC;
 106        s->s_op = &capifs_sops;
 107        s->s_time_gran = 1;
 108
 109        inode = new_inode(s);
 110        if (!inode)
 111                goto fail;
 112        inode->i_ino = 1;
 113        inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 114        inode->i_blocks = 0;
 115        inode->i_uid = inode->i_gid = 0;
 116        inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
 117        inode->i_op = &simple_dir_inode_operations;
 118        inode->i_fop = &simple_dir_operations;
 119        inode->i_nlink = 2;
 120
 121        capifs_root = s->s_root = d_alloc_root(inode);
 122        if (s->s_root)
 123                return 0;
 124        
 125        printk("capifs: get root dentry failed\n");
 126        iput(inode);
 127fail:
 128        return -ENOMEM;
 129}
 130
 131static int capifs_get_sb(struct file_system_type *fs_type,
 132        int flags, const char *dev_name, void *data, struct vfsmount *mnt)
 133{
 134        return get_sb_single(fs_type, flags, data, capifs_fill_super, mnt);
 135}
 136
 137static struct file_system_type capifs_fs_type = {
 138        .owner          = THIS_MODULE,
 139        .name           = "capifs",
 140        .get_sb         = capifs_get_sb,
 141        .kill_sb        = kill_anon_super,
 142};
 143
 144static struct dentry *get_node(int num)
 145{
 146        char s[10];
 147        struct dentry *root = capifs_root;
 148        mutex_lock(&root->d_inode->i_mutex);
 149        return lookup_one_len(s, root, sprintf(s, "%d", num));
 150}
 151
 152void capifs_new_ncci(unsigned int number, dev_t device)
 153{
 154        struct dentry *dentry;
 155        struct inode *inode = new_inode(capifs_mnt->mnt_sb);
 156        if (!inode)
 157                return;
 158        inode->i_ino = number+2;
 159        inode->i_uid = config.setuid ? config.uid : current->fsuid;
 160        inode->i_gid = config.setgid ? config.gid : current->fsgid;
 161        inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 162        init_special_inode(inode, S_IFCHR|config.mode, device);
 163        //inode->i_op = &capifs_file_inode_operations;
 164
 165        dentry = get_node(number);
 166        if (!IS_ERR(dentry) && !dentry->d_inode)
 167                d_instantiate(dentry, inode);
 168        mutex_unlock(&capifs_root->d_inode->i_mutex);
 169}
 170
 171void capifs_free_ncci(unsigned int number)
 172{
 173        struct dentry *dentry = get_node(number);
 174
 175        if (!IS_ERR(dentry)) {
 176                struct inode *inode = dentry->d_inode;
 177                if (inode) {
 178                        inode->i_nlink--;
 179                        d_delete(dentry);
 180                        dput(dentry);
 181                }
 182                dput(dentry);
 183        }
 184        mutex_unlock(&capifs_root->d_inode->i_mutex);
 185}
 186
 187static int __init capifs_init(void)
 188{
 189        char rev[32];
 190        char *p;
 191        int err;
 192
 193        if ((p = strchr(revision, ':')) != NULL && p[1]) {
 194                strlcpy(rev, p + 2, sizeof(rev));
 195                if ((p = strchr(rev, '$')) != NULL && p > rev)
 196                   *(p-1) = 0;
 197        } else
 198                strcpy(rev, "1.0");
 199
 200        err = register_filesystem(&capifs_fs_type);
 201        if (!err) {
 202                capifs_mnt = kern_mount(&capifs_fs_type);
 203                if (IS_ERR(capifs_mnt)) {
 204                        err = PTR_ERR(capifs_mnt);
 205                        unregister_filesystem(&capifs_fs_type);
 206                }
 207        }
 208        if (!err)
 209                printk(KERN_NOTICE "capifs: Rev %s\n", rev);
 210        return err;
 211}
 212
 213static void __exit capifs_exit(void)
 214{
 215        unregister_filesystem(&capifs_fs_type);
 216        mntput(capifs_mnt);
 217}
 218
 219EXPORT_SYMBOL(capifs_new_ncci);
 220EXPORT_SYMBOL(capifs_free_ncci);
 221
 222module_init(capifs_init);
 223module_exit(capifs_exit);
 224