fs/readdir.c

   1 /*
   2  *  linux/fs/readdir.c
   3  *
   4  *  Copyright (C) 1995  Linus Torvalds
   5  */
   6
   7 #include <linux/module.h>
   8 #include <linux/time.h>
   9 #include <linux/mm.h>
  10 #include <linux/errno.h>
  11 #include <linux/stat.h>
  12 #include <linux/file.h>
  13 #include <linux/smp_lock.h>
  14 #include <linux/fs.h>
  15 #include <linux/dirent.h>
  16 #include <linux/security.h>
  17 #include <linux/syscalls.h>
  18 #include <linux/unistd.h>
  19
  20 #include <asm/uaccess.h>
  21
  22 int vfs_readdir(struct file *file, filldir_t filler, void *buf)
  23 {
  24         struct inode *inode = file->f_dentry->d_inode;
  25         int res = -ENOTDIR;
  26         if (!file->f_op || !file->f_op->readdir)
  27                 goto out;
  28
  29         res = security_file_permission(file, MAY_READ);
  30         if (res)
  31                 goto out;
  32
  33         mutex_lock(&inode->i_mutex);
  34         res = -ENOENT;
  35         if (!IS_DEADDIR(inode)) {
  36                 res = file->f_op->readdir(file, buf, filler);
  37                 file_accessed(file);
  38         }
  39         mutex_unlock(&inode->i_mutex);
  40 out:
  41         return res;
  42 }
  43
  44 EXPORT_SYMBOL(vfs_readdir);
  45
  46 /*
  47  * Traditional linux readdir() handling..
  48  *
  49  * "count=1" is a special case, meaning that the buffer is one
  50  * dirent-structure in size and that the code can't handle more
  51  * anyway. Thus the special "fillonedir()" function for that
  52  * case (the low-level handlers don't need to care about this).
  53  */
  54 #define NAME_OFFSET(de) ((int) ((de)->d_name - (char __user *) (de)))
  55 #define ROUND_UP(x) (((x)+sizeof(long)-1) & ~(sizeof(long)-1))
  56
  57 #ifdef __ARCH_WANT_OLD_READDIR
  58
  59 struct old_linux_dirent {
  60         unsigned long   d_ino;
  61         unsigned long   d_offset;
  62         unsigned short  d_namlen;
  63         char            d_name[1];
  64 };
  65
  66 struct readdir_callback {
  67         struct old_linux_dirent __user * dirent;
  68         int result;
  69 };
  70
  71 static int fillonedir(void * __buf, const char * name, int namlen, loff_t offset,
  72                       u64 ino, unsigned int d_type)
  73 {
  74         struct readdir_callback * buf = (struct readdir_callback *) __buf;
  75         struct old_linux_dirent __user * dirent;
  76         unsigned long d_ino;
  77
  78         if (buf->result)
  79                 return -EINVAL;
  80         d_ino = ino;
  81         if (sizeof(d_ino) < sizeof(ino) && d_ino != ino)
  82                 return -EOVERFLOW;
  83         buf->result++;
  84         dirent = buf->dirent;
  85         if (!access_ok(VERIFY_WRITE, dirent,
  86                         (unsigned long)(dirent->d_name + namlen + 1) -
  87                                 (unsigned long)dirent))
  88                 goto efault;
  89         if (    __put_user(d_ino, &dirent->d_ino) ||
  90                 __put_user(offset, &dirent->d_offset) ||
  91                 __put_user(namlen, &dirent->d_namlen) ||
  92                 __copy_to_user(dirent->d_name, name, namlen) ||
  93                 __put_user(0, dirent->d_name + namlen))
  94                 goto efault;
  95         return 0;
  96 efault:
  97         buf->result = -EFAULT;
  98         return -EFAULT;
  99 }
 100
 101 asmlinkage long old_readdir(unsigned int fd, struct old_linux_dirent __user * dirent, unsigned int count)
 102 {
 103         int error;
 104         struct file * file;
 105         struct readdir_callback buf;
 106
 107         error = -EBADF;
 108         file = fget(fd);
 109         if (!file)
 110                 goto out;
 111
 112         buf.result = 0;
 113         buf.dirent = dirent;
 114
 115         error = vfs_readdir(file, fillonedir, &buf);
 116         if (error >= 0)
 117                 error = buf.result;
 118
 119         fput(file);
 120 out:
 121         return error;
 122 }
 123
 124 #endif /* __ARCH_WANT_OLD_READDIR */
 125
 126 /*
 127  * New, all-improved, singing, dancing, iBCS2-compliant getdents()
 128  * interface.
 129  */
 130 struct linux_dirent {
 131         unsigned long   d_ino;
 132         unsigned long   d_off;
 133         unsigned short  d_reclen;
 134         char            d_name[1];
 135 };
 136
 137 struct getdents_callback {
 138         struct linux_dirent __user * current_dir;
 139         struct linux_dirent __user * previous;
 140         int count;
 141         int error;
 142 };
 143
 144 static int filldir(void * __buf, const char * name, int namlen, loff_t offset,
 145                    u64 ino, unsigned int d_type)
 146 {
 147         struct linux_dirent __user * dirent;
 148         struct getdents_callback * buf = (struct getdents_callback *) __buf;
 149         unsigned long d_ino;
 150         int reclen = ROUND_UP(NAME_OFFSET(dirent) + namlen + 2);
 151
 152         buf->error = -EINVAL;   /* only used if we fail.. */
 153         if (reclen > buf->count)
 154                 return -EINVAL;
 155         d_ino = ino;
 156         if (sizeof(d_ino) < sizeof(ino) && d_ino != ino)
 157                 return -EOVERFLOW;
 158         dirent = buf->previous;
 159         if (dirent) {
 160                 if (__put_user(offset, &dirent->d_off))
 161                         goto efault;
 162         }
 163         dirent = buf->current_dir;
 164         if (__put_user(d_ino, &dirent->d_ino))
 165                 goto efault;
 166         if (__put_user(reclen, &dirent->d_reclen))
 167                 goto efault;
 168         if (copy_to_user(dirent->d_name, name, namlen))
 169                 goto efault;
 170         if (__put_user(0, dirent->d_name + namlen))
 171                 goto efault;
 172         if (__put_user(d_type, (char __user *) dirent + reclen - 1))
 173                 goto efault;
 174         buf->previous = dirent;
 175         dirent = (void __user *)dirent + reclen;
 176         buf->current_dir = dirent;
 177         buf->count -= reclen;
 178         return 0;
 179 efault:
 180         buf->error = -EFAULT;
 181         return -EFAULT;
 182 }
 183
 184 asmlinkage long sys_getdents(unsigned int fd, struct linux_dirent __user * dirent, unsigned int count)
 185 {
 186         struct file * file;
 187         struct linux_dirent __user * lastdirent;
 188         struct getdents_callback buf;
 189         int error;
 190
 191         error = -EFAULT;
 192         if (!access_ok(VERIFY_WRITE, dirent, count))
 193                 goto out;
 194
 195         error = -EBADF;
 196         file = fget(fd);
 197         if (!file)
 198                 goto out;
 199
 200         buf.current_dir = dirent;
 201         buf.previous = NULL;
 202         buf.count = count;
 203         buf.error = 0;
 204
 205         error = vfs_readdir(file, filldir, &buf);
 206         if (error < 0)
 207                 goto out_putf;
 208         error = buf.error;
 209         lastdirent = buf.previous;
 210         if (lastdirent) {
 211                 if (put_user(file->f_pos, &lastdirent->d_off))
 212                         error = -EFAULT;
 213                 else
 214                         error = count - buf.count;
 215         }
 216
 217 out_putf:
 218         fput(file);
 219 out:
 220         return error;
 221 }
 222
 223 #define ROUND_UP64(x) (((x)+sizeof(u64)-1) & ~(sizeof(u64)-1))
 224
 225 struct getdents_callback64 {
 226         struct linux_dirent64 __user * current_dir;
 227         struct linux_dirent64 __user * previous;
 228         int count;
 229         int error;
 230 };
 231
 232 static int filldir64(void * __buf, const char * name, int namlen, loff_t offset,
 233                      u64 ino, unsigned int d_type)
 234 {
 235         struct linux_dirent64 __user *dirent;
 236         struct getdents_callback64 * buf = (struct getdents_callback64 *) __buf;
 237         int reclen = ROUND_UP64(NAME_OFFSET(dirent) + namlen + 1);
 238
 239         buf->error = -EINVAL;   /* only used if we fail.. */
 240         if (reclen > buf->count)
 241                 return -EINVAL;
 242         dirent = buf->previous;
 243         if (dirent) {
 244                 if (__put_user(offset, &dirent->d_off))
 245                         goto efault;
 246         }
 247         dirent = buf->current_dir;
 248         if (__put_user(ino, &dirent->d_ino))
 249                 goto efault;
 250         if (__put_user(0, &dirent->d_off))
 251                 goto efault;
 252         if (__put_user(reclen, &dirent->d_reclen))
 253                 goto efault;
 254         if (__put_user(d_type, &dirent->d_type))
 255                 goto efault;
 256         if (copy_to_user(dirent->d_name, name, namlen))
 257                 goto efault;
 258         if (__put_user(0, dirent->d_name + namlen))
 259                 goto efault;
 260         buf->previous = dirent;
 261         dirent = (void __user *)dirent + reclen;
 262         buf->current_dir = dirent;
 263         buf->count -= reclen;
 264         return 0;
 265 efault:
 266         buf->error = -EFAULT;
 267         return -EFAULT;
 268 }
 269
 270 asmlinkage long sys_getdents64(unsigned int fd, struct linux_dirent64 __user * dirent, unsigned int count)
 271 {
 272         struct file * file;
 273         struct linux_dirent64 __user * lastdirent;
 274         struct getdents_callback64 buf;
 275         int error;
 276
 277         error = -EFAULT;
 278         if (!access_ok(VERIFY_WRITE, dirent, count))
 279                 goto out;
 280
 281         error = -EBADF;
 282         file = fget(fd);
 283         if (!file)
 284                 goto out;
 285
 286         buf.current_dir = dirent;
 287         buf.previous = NULL;
 288         buf.count = count;
 289         buf.error = 0;
 290
 291         error = vfs_readdir(file, filldir64, &buf);
 292         if (error < 0)
 293                 goto out_putf;
 294         error = buf.error;
 295         lastdirent = buf.previous;
 296         if (lastdirent) {
 297                 typeof(lastdirent->d_off) d_off = file->f_pos;
 298                 error = -EFAULT;
 299                 if (__put_user(d_off, &lastdirent->d_off))
 300                         goto out_putf;
 301                 error = count - buf.count;
 302         }
 303
 304 out_putf:
 305         fput(file);
 306 out:
 307         return error;
 308 }