fs/devpts/inode.c

   1 /* -*- linux-c -*- --------------------------------------------------------- *
   2  *
   3  * linux/fs/devpts/inode.c
   4  *
   5  *  Copyright 1998 H. Peter Anvin -- All Rights Reserved
   6  *
   7  * This file is part of the Linux kernel and is made available under
   8  * the terms of the GNU General Public License, version 2, or at your
   9  * option, any later version, incorporated herein by reference.
  10  *
  11  * ------------------------------------------------------------------------- */
  12
  13 #include <linux/module.h>
  14
  15 #include <linux/string.h>
  16 #include <linux/fs.h>
  17 #include <linux/init.h>
  18 #include <linux/kdev_t.h>
  19 #include <linux/kernel.h>
  20 #include <linux/locks.h>
  21 #include <linux/major.h>
  22 #include <linux/slab.h>
  23 #include <linux/stat.h>
  24 #include <linux/tty.h>
  25 #include <asm/bitops.h>
  26 #include <asm/uaccess.h>
  27
  28 #include "devpts_i.h"
  29
  30 static struct vfsmount *devpts_mnt;
  31
  32 static void devpts_put_super(struct super_block *sb)
  33 {
  34         struct devpts_sb_info *sbi = SBI(sb);
  35         struct inode *inode;
  36         int i;
  37
  38         for ( i = 0 ; i < sbi->max_ptys ; i++ ) {
  39                 if ( (inode = sbi->inodes[i]) ) {
  40                         if ( atomic_read(&inode->i_count) != 1 )
  41                                 printk("devpts_put_super: badness: entry %d count %d\n",
  42                                        i, atomic_read(&inode->i_count));
  43                         inode->i_nlink--;
  44                         iput(inode);
  45                 }
  46         }
  47         kfree(sbi->inodes);
  48         kfree(sbi);
  49 }
  50
  51 static int devpts_statfs(struct super_block *sb, struct statfs *buf);
  52 static int devpts_remount (struct super_block * sb, int * flags, char * data);
  53
  54 static struct super_operations devpts_sops = {
  55         put_super:      devpts_put_super,
  56         statfs:         devpts_statfs,
  57         remount_fs:     devpts_remount,
  58 };
  59
  60 static int devpts_parse_options(char *options, struct devpts_sb_info *sbi)
  61 {
  62         int setuid = 0;
  63         int setgid = 0;
  64         uid_t uid = 0;
  65         gid_t gid = 0;
  66         umode_t mode = 0600;
  67         char *this_char, *value;
  68
  69         this_char = NULL;
  70         if ( options )
  71                 this_char = strtok(options,",");
  72         for ( ; this_char; this_char = strtok(NULL,",")) {
  73                 if ((value = strchr(this_char,'=')) != NULL)
  74                         *value++ = 0;
  75                 if (!strcmp(this_char,"uid")) {
  76                         if (!value || !*value)
  77                                 return 1;
  78                         uid = simple_strtoul(value,&value,0);
  79                         if (*value)
  80                                 return 1;
  81                         setuid = 1;
  82                 }
  83                 else if (!strcmp(this_char,"gid")) {
  84                         if (!value || !*value)
  85                                 return 1;
  86                         gid = simple_strtoul(value,&value,0);
  87                         if (*value)
  88                                 return 1;
  89                         setgid = 1;
  90                 }
  91                 else if (!strcmp(this_char,"mode")) {
  92                         if (!value || !*value)
  93                                 return 1;
  94                         mode = simple_strtoul(value,&value,8);
  95                         if (*value)
  96                                 return 1;
  97                 }
  98                 else
  99                         return 1;
 100         }
 101         sbi->setuid  = setuid;
 102         sbi->setgid  = setgid;
 103         sbi->uid     = uid;
 104         sbi->gid     = gid;
 105         sbi->mode    = mode & ~S_IFMT;
 106
 107         return 0;
 108 }
 109
 110 static int devpts_remount(struct super_block * sb, int * flags, char * data)
 111 {
 112         struct devpts_sb_info *sbi = sb->u.generic_sbp;
 113         int res = devpts_parse_options(data,sbi);
 114         if (res) {
 115                 printk("devpts: called with bogus options\n");
 116                 return -EINVAL;
 117         }
 118         return 0;
 119 }
 120
 121 struct super_block *devpts_read_super(struct super_block *s, void *data,
 122                                       int silent)
 123 {
 124         struct inode * inode;
 125         struct devpts_sb_info *sbi;
 126
 127         sbi = (struct devpts_sb_info *) kmalloc(sizeof(struct devpts_sb_info), GFP_KERNEL);
 128         if ( !sbi )
 129                 goto fail;
 130
 131         sbi->magic  = DEVPTS_SBI_MAGIC;
 132         sbi->max_ptys = unix98_max_ptys;
 133         sbi->inodes = kmalloc(sizeof(struct inode *) * sbi->max_ptys, GFP_KERNEL);
 134         if ( !sbi->inodes )
 135                 goto fail_free;
 136         memset(sbi->inodes, 0, sizeof(struct inode *) * sbi->max_ptys);
 137
 138         if ( devpts_parse_options(data,sbi) && !silent) {
 139                 printk("devpts: called with bogus options\n");
 140                 goto fail_inode;
 141         }
 142
 143         inode = new_inode(s);
 144         if (!inode)
 145                 goto fail_inode;
 146         inode->i_ino = 1;
 147         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 148         inode->i_blocks = 0;
 149         inode->i_blksize = 1024;
 150         inode->i_uid = inode->i_gid = 0;
 151         inode->i_mode = S_IFDIR | S_IRUGO | S_IXUGO | S_IWUSR;
 152         inode->i_op = &devpts_root_inode_operations;
 153         inode->i_fop = &devpts_root_operations;
 154         inode->i_nlink = 2;
 155
 156         s->u.generic_sbp = (void *) sbi;
 157         s->s_blocksize = 1024;
 158         s->s_blocksize_bits = 10;
 159         s->s_magic = DEVPTS_SUPER_MAGIC;
 160         s->s_op = &devpts_sops;
 161         s->s_root = d_alloc_root(inode);
 162         if (s->s_root)
 163                 return s;
 164
 165         printk("devpts: get root dentry failed\n");
 166         iput(inode);
 167 fail_inode:
 168         kfree(sbi->inodes);
 169 fail_free:
 170         kfree(sbi);
 171 fail:
 172         return NULL;
 173 }
 174
 175 static int devpts_statfs(struct super_block *sb, struct statfs *buf)
 176 {
 177         buf->f_type = DEVPTS_SUPER_MAGIC;
 178         buf->f_bsize = 1024;
 179         buf->f_namelen = NAME_MAX;
 180         return 0;
 181 }
 182
 183 static DECLARE_FSTYPE(devpts_fs_type, "devpts", devpts_read_super, FS_SINGLE);
 184
 185 void devpts_pty_new(int number, kdev_t device)
 186 {
 187         struct super_block *sb = devpts_mnt->mnt_sb;
 188         struct devpts_sb_info *sbi = SBI(sb);
 189         struct inode *inode;
 190
 191         if ( sbi->inodes[number] )
 192                 return; /* Already registered, this does happen */
 193
 194         inode = new_inode(sb);
 195         if (!inode)
 196                 return;
 197         inode->i_ino = number+2;
 198         inode->i_blocks = 0;
 199         inode->i_blksize = 1024;
 200         inode->i_uid = sbi->setuid ? sbi->uid : current->fsuid;
 201         inode->i_gid = sbi->setgid ? sbi->gid : current->fsgid;
 202         inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
 203         init_special_inode(inode, S_IFCHR|sbi->mode, kdev_t_to_nr(device));
 204
 205         if ( sbi->inodes[number] ) {
 206                 iput(inode);
 207                 return;
 208         }
 209         sbi->inodes[number] = inode;
 210 }
 211
 212 void devpts_pty_kill(int number)
 213 {
 214         struct super_block *sb = devpts_mnt->mnt_sb;
 215         struct devpts_sb_info *sbi = SBI(sb);
 216         struct inode *inode = sbi->inodes[number];
 217
 218         if ( inode ) {
 219                 sbi->inodes[number] = NULL;
 220                 inode->i_nlink--;
 221                 iput(inode);
 222         }
 223 }
 224
 225 static int __init init_devpts_fs(void)
 226 {
 227         int err = register_filesystem(&devpts_fs_type);
 228         if (!err) {
 229                 devpts_mnt = kern_mount(&devpts_fs_type);
 230                 err = PTR_ERR(devpts_mnt);
 231                 if (!IS_ERR(devpts_mnt))
 232                         err = 0;
 233 #ifdef MODULE
 234                 if ( !err ) {
 235                         devpts_upcall_new  = devpts_pty_new;
 236                         devpts_upcall_kill = devpts_pty_kill;
 237                 }
 238 #endif
 239         }
 240         return err;
 241 }
 242
 243 static void __exit exit_devpts_fs(void)
 244 {
 245 #ifdef MODULE
 246         devpts_upcall_new  = NULL;
 247         devpts_upcall_kill = NULL;
 248 #endif
 249         unregister_filesystem(&devpts_fs_type);
 250         kern_umount(devpts_mnt);
 251 }
 252
 253 module_init(init_devpts_fs)
 254 module_exit(exit_devpts_fs)
 255 MODULE_LICENSE("GPL");
 256