drivers/isdn/capi/capifs.c

   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
  22 MODULE_DESCRIPTION("CAPI4Linux: /dev/capi/ filesystem");
  23 MODULE_AUTHOR("Carsten Paeth");
  24 MODULE_LICENSE("GPL");
  25
  26 /* ------------------------------------------------------------------ */
  27
  28 static char *revision = "$Revision: 1.1.2.3 $";
  29
  30 /* ------------------------------------------------------------------ */
  31
  32 #define CAPIFS_SUPER_MAGIC (('C'<<8)|'N')
  33
  34 static struct vfsmount *capifs_mnt;
  35 static struct dentry *capifs_root;
  36
  37 static 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
  47 static 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
  56         this_char = NULL;
  57         while ((this_char = strsep(&data, ",")) != NULL) {
  58                 int n;
  59                 char dummy;
  60                 if (!*this_char)
  61                         continue;
  62                 if (sscanf(this_char, "uid=%i%c", &n, &dummy) == 1) {
  63                         setuid = 1;
  64                         uid = n;
  65                 } else if (sscanf(this_char, "gid=%i%c", &n, &dummy) == 1) {
  66                         setgid = 1;
  67                         gid = n;
  68                 } else if (sscanf(this_char, "mode=%o%c", &n, &dummy) == 1)
  69                         mode = n & ~S_IFMT;
  70                 else {
  71                         printk("capifs: called with bogus options\n");
  72                         return -EINVAL;
  73                 }
  74         }
  75         config.setuid  = setuid;
  76         config.setgid  = setgid;
  77         config.uid     = uid;
  78         config.gid     = gid;
  79         config.mode    = mode;
  80         return 0;
  81 }
  82
  83 static struct super_operations capifs_sops =
  84 {
  85         .statfs         = simple_statfs,
  86         .remount_fs     = capifs_remount,
  87 };
  88
  89
  90 static int
  91 capifs_fill_super(struct super_block *s, void *data, int silent)
  92 {
  93         struct inode * inode;
  94
  95         s->s_blocksize = 1024;
  96         s->s_blocksize_bits = 10;
  97         s->s_magic = CAPIFS_SUPER_MAGIC;
  98         s->s_op = &capifs_sops;
  99         s->s_time_gran = 1;
 100
 101         inode = new_inode(s);
 102         if (!inode)
 103                 goto fail;
 104         inode->i_ino = 1;
 105         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 106         inode->i_blocks = 0;
 107         inode->i_blksize = 1024;
 108         inode->i_uid = inode->i_gid = 0;
 109         inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
 110         inode->i_op = &simple_dir_inode_operations;
 111         inode->i_fop = &simple_dir_operations;
 112         inode->i_nlink = 2;
 113
 114         capifs_root = s->s_root = d_alloc_root(inode);
 115         if (s->s_root)
 116                 return 0;
 117
 118         printk("capifs: get root dentry failed\n");
 119         iput(inode);
 120 fail:
 121         return -ENOMEM;
 122 }
 123
 124 static struct super_block *capifs_get_sb(struct file_system_type *fs_type,
 125         int flags, const char *dev_name, void *data)
 126 {
 127         return get_sb_single(fs_type, flags, data, capifs_fill_super);
 128 }
 129
 130 static struct file_system_type capifs_fs_type = {
 131         .owner          = THIS_MODULE,
 132         .name           = "capifs",
 133         .get_sb         = capifs_get_sb,
 134         .kill_sb        = kill_anon_super,
 135 };
 136
 137 static struct dentry *get_node(int num)
 138 {
 139         char s[10];
 140         struct dentry *root = capifs_root;
 141         mutex_lock(&root->d_inode->i_mutex);
 142         return lookup_one_len(s, root, sprintf(s, "%d", num));
 143 }
 144
 145 void capifs_new_ncci(unsigned int number, dev_t device)
 146 {
 147         struct dentry *dentry;
 148         struct inode *inode = new_inode(capifs_mnt->mnt_sb);
 149         if (!inode)
 150                 return;
 151         inode->i_ino = number+2;
 152         inode->i_blksize = 1024;
 153         inode->i_uid = config.setuid ? config.uid : current->fsuid;
 154         inode->i_gid = config.setgid ? config.gid : current->fsgid;
 155         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 156         init_special_inode(inode, S_IFCHR|config.mode, device);
 157         //inode->i_op = &capifs_file_inode_operations;
 158
 159         dentry = get_node(number);
 160         if (!IS_ERR(dentry) && !dentry->d_inode)
 161                 d_instantiate(dentry, inode);
 162         mutex_unlock(&capifs_root->d_inode->i_mutex);
 163 }
 164
 165 void capifs_free_ncci(unsigned int number)
 166 {
 167         struct dentry *dentry = get_node(number);
 168
 169         if (!IS_ERR(dentry)) {
 170                 struct inode *inode = dentry->d_inode;
 171                 if (inode) {
 172                         inode->i_nlink--;
 173                         d_delete(dentry);
 174                         dput(dentry);
 175                 }
 176                 dput(dentry);
 177         }
 178         mutex_unlock(&capifs_root->d_inode->i_mutex);
 179 }
 180
 181 static int __init capifs_init(void)
 182 {
 183         char rev[32];
 184         char *p;
 185         int err;
 186
 187         if ((p = strchr(revision, ':')) != 0 && p[1]) {
 188                 strlcpy(rev, p + 2, sizeof(rev));
 189                 if ((p = strchr(rev, '$')) != 0 && p > rev)
 190                    *(p-1) = 0;
 191         } else
 192                 strcpy(rev, "1.0");
 193
 194         err = register_filesystem(&capifs_fs_type);
 195         if (!err) {
 196                 capifs_mnt = kern_mount(&capifs_fs_type);
 197                 if (IS_ERR(capifs_mnt)) {
 198                         err = PTR_ERR(capifs_mnt);
 199                         unregister_filesystem(&capifs_fs_type);
 200                 }
 201         }
 202         if (!err)
 203                 printk(KERN_NOTICE "capifs: Rev %s\n", rev);
 204         return err;
 205 }
 206
 207 static void __exit capifs_exit(void)
 208 {
 209         unregister_filesystem(&capifs_fs_type);
 210         mntput(capifs_mnt);
 211 }
 212
 213 EXPORT_SYMBOL(capifs_new_ncci);
 214 EXPORT_SYMBOL(capifs_free_ncci);
 215
 216 module_init(capifs_init);
 217 module_exit(capifs_exit);