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_uid = inode->i_gid = 0;
 108         inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
 109         inode->i_op = &simple_dir_inode_operations;
 110         inode->i_fop = &simple_dir_operations;
 111         inode->i_nlink = 2;
 112
 113         capifs_root = s->s_root = d_alloc_root(inode);
 114         if (s->s_root)
 115                 return 0;
 116
 117         printk("capifs: get root dentry failed\n");
 118         iput(inode);
 119 fail:
 120         return -ENOMEM;
 121 }
 122
 123 static int capifs_get_sb(struct file_system_type *fs_type,
 124         int flags, const char *dev_name, void *data, struct vfsmount *mnt)
 125 {
 126         return get_sb_single(fs_type, flags, data, capifs_fill_super, mnt);
 127 }
 128
 129 static struct file_system_type capifs_fs_type = {
 130         .owner          = THIS_MODULE,
 131         .name           = "capifs",
 132         .get_sb         = capifs_get_sb,
 133         .kill_sb        = kill_anon_super,
 134 };
 135
 136 static struct dentry *get_node(int num)
 137 {
 138         char s[10];
 139         struct dentry *root = capifs_root;
 140         mutex_lock(&root->d_inode->i_mutex);
 141         return lookup_one_len(s, root, sprintf(s, "%d", num));
 142 }
 143
 144 void capifs_new_ncci(unsigned int number, dev_t device)
 145 {
 146         struct dentry *dentry;
 147         struct inode *inode = new_inode(capifs_mnt->mnt_sb);
 148         if (!inode)
 149                 return;
 150         inode->i_ino = number+2;
 151         inode->i_uid = config.setuid ? config.uid : current->fsuid;
 152         inode->i_gid = config.setgid ? config.gid : current->fsgid;
 153         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 154         init_special_inode(inode, S_IFCHR|config.mode, device);
 155         //inode->i_op = &capifs_file_inode_operations;
 156
 157         dentry = get_node(number);
 158         if (!IS_ERR(dentry) && !dentry->d_inode)
 159                 d_instantiate(dentry, inode);
 160         mutex_unlock(&capifs_root->d_inode->i_mutex);
 161 }
 162
 163 void capifs_free_ncci(unsigned int number)
 164 {
 165         struct dentry *dentry = get_node(number);
 166
 167         if (!IS_ERR(dentry)) {
 168                 struct inode *inode = dentry->d_inode;
 169                 if (inode) {
 170                         inode->i_nlink--;
 171                         d_delete(dentry);
 172                         dput(dentry);
 173                 }
 174                 dput(dentry);
 175         }
 176         mutex_unlock(&capifs_root->d_inode->i_mutex);
 177 }
 178
 179 static int __init capifs_init(void)
 180 {
 181         char rev[32];
 182         char *p;
 183         int err;
 184
 185         if ((p = strchr(revision, ':')) != 0 && p[1]) {
 186                 strlcpy(rev, p + 2, sizeof(rev));
 187                 if ((p = strchr(rev, '$')) != 0 && p > rev)
 188                    *(p-1) = 0;
 189         } else
 190                 strcpy(rev, "1.0");
 191
 192         err = register_filesystem(&capifs_fs_type);
 193         if (!err) {
 194                 capifs_mnt = kern_mount(&capifs_fs_type);
 195                 if (IS_ERR(capifs_mnt)) {
 196                         err = PTR_ERR(capifs_mnt);
 197                         unregister_filesystem(&capifs_fs_type);
 198                 }
 199         }
 200         if (!err)
 201                 printk(KERN_NOTICE "capifs: Rev %s\n", rev);
 202         return err;
 203 }
 204
 205 static void __exit capifs_exit(void)
 206 {
 207         unregister_filesystem(&capifs_fs_type);
 208         mntput(capifs_mnt);
 209 }
 210
 211 EXPORT_SYMBOL(capifs_new_ncci);
 212 EXPORT_SYMBOL(capifs_free_ncci);
 213
 214 module_init(capifs_init);
 215 module_exit(capifs_exit);