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         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         mutex_lock(&s->s_root->d_inode->i_mutex);
  79
  80         replace_mount_options(s, new_opt);
  81         config.setuid  = setuid;
  82         config.setgid  = setgid;
  83         config.uid     = uid;
  84         config.gid     = gid;
  85         config.mode    = mode;
  86
  87         mutex_unlock(&s->s_root->d_inode->i_mutex);
  88
  89         return 0;
  90 }
  91
  92 static const struct super_operations capifs_sops =
  93 {
  94         .statfs         = simple_statfs,
  95         .remount_fs     = capifs_remount,
  96         .show_options   = generic_show_options,
  97 };
  98
  99
 100 static int
 101 capifs_fill_super(struct super_block *s, void *data, int silent)
 102 {
 103         struct inode * inode;
 104
 105         s->s_blocksize = 1024;
 106         s->s_blocksize_bits = 10;
 107         s->s_magic = CAPIFS_SUPER_MAGIC;
 108         s->s_op = &capifs_sops;
 109         s->s_time_gran = 1;
 110
 111         inode = new_inode(s);
 112         if (!inode)
 113                 goto fail;
 114         inode->i_ino = 1;
 115         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 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);
 127 fail:
 128         return -ENOMEM;
 129 }
 130
 131 static 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
 137 static 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
 144 static 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
 152 void 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
 160         dentry = get_node(number);
 161
 162         /* config contents is protected by root's i_mutex */
 163         inode->i_uid = config.setuid ? config.uid : current_fsuid();
 164         inode->i_gid = config.setgid ? config.gid : current_fsgid();
 165         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 166         init_special_inode(inode, S_IFCHR|config.mode, device);
 167         //inode->i_op = &capifs_file_inode_operations;
 168
 169         if (!IS_ERR(dentry) && !dentry->d_inode)
 170                 d_instantiate(dentry, inode);
 171         mutex_unlock(&capifs_root->d_inode->i_mutex);
 172 }
 173
 174 void capifs_free_ncci(unsigned int number)
 175 {
 176         struct dentry *dentry = get_node(number);
 177
 178         if (!IS_ERR(dentry)) {
 179                 struct inode *inode = dentry->d_inode;
 180                 if (inode) {
 181                         inode->i_nlink--;
 182                         d_delete(dentry);
 183                         dput(dentry);
 184                 }
 185                 dput(dentry);
 186         }
 187         mutex_unlock(&capifs_root->d_inode->i_mutex);
 188 }
 189
 190 static int __init capifs_init(void)
 191 {
 192         char rev[32];
 193         char *p;
 194         int err;
 195
 196         if ((p = strchr(revision, ':')) != NULL && p[1]) {
 197                 strlcpy(rev, p + 2, sizeof(rev));
 198                 if ((p = strchr(rev, '$')) != NULL && p > rev)
 199                    *(p-1) = 0;
 200         } else
 201                 strcpy(rev, "1.0");
 202
 203         err = register_filesystem(&capifs_fs_type);
 204         if (!err) {
 205                 capifs_mnt = kern_mount(&capifs_fs_type);
 206                 if (IS_ERR(capifs_mnt)) {
 207                         err = PTR_ERR(capifs_mnt);
 208                         unregister_filesystem(&capifs_fs_type);
 209                 }
 210         }
 211         if (!err)
 212                 printk(KERN_NOTICE "capifs: Rev %s\n", rev);
 213         return err;
 214 }
 215
 216 static void __exit capifs_exit(void)
 217 {
 218         unregister_filesystem(&capifs_fs_type);
 219         mntput(capifs_mnt);
 220 }
 221
 222 EXPORT_SYMBOL(capifs_new_ncci);
 223 EXPORT_SYMBOL(capifs_free_ncci);
 224
 225 module_init(capifs_init);
 226 module_exit(capifs_exit);