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         down(&inode->i_sem);
  34         res = -ENOENT;
  35         if (!IS_DEADDIR(inode)) {
  36                 res = file->f_op->readdir(file, buf, filler);
  37                 file_accessed(file);
  38         }
  39         up(&inode->i_sem);
  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                       ino_t ino, unsigned int d_type)
  73 {
  74         struct readdir_callback * buf = (struct readdir_callback *) __buf;
  75         struct old_linux_dirent __user * dirent;
  76
  77         if (buf->result)
  78                 return -EINVAL;
  79         buf->result++;
  80         dirent = buf->dirent;
  81         if (!access_ok(VERIFY_WRITE, dirent,
  82                         (unsigned long)(dirent->d_name + namlen + 1) -
  83                                 (unsigned long)dirent))
  84                 goto efault;
  85         if (    __put_user(ino, &dirent->d_ino) ||
  86                 __put_user(offset, &dirent->d_offset) ||
  87                 __put_user(namlen, &dirent->d_namlen) ||
  88                 __copy_to_user(dirent->d_name, name, namlen) ||
  89                 __put_user(0, dirent->d_name + namlen))
  90                 goto efault;
  91         return 0;
  92 efault:
  93         buf->result = -EFAULT;
  94         return -EFAULT;
  95 }
  96
  97 asmlinkage long old_readdir(unsigned int fd, struct old_linux_dirent __user * dirent, unsigned int count)
  98 {
  99         int error;
 100         struct file * file;
 101         struct readdir_callback buf;
 102
 103         error = -EBADF;
 104         file = fget(fd);
 105         if (!file)
 106                 goto out;
 107
 108         buf.result = 0;
 109         buf.dirent = dirent;
 110
 111         error = vfs_readdir(file, fillonedir, &buf);
 112         if (error >= 0)
 113                 error = buf.result;
 114
 115         fput(file);
 116 out:
 117         return error;
 118 }
 119
 120 #endif /* __ARCH_WANT_OLD_READDIR */
 121
 122 /*
 123  * New, all-improved, singing, dancing, iBCS2-compliant getdents()
 124  * interface.
 125  */
 126 struct linux_dirent {
 127         unsigned long   d_ino;
 128         unsigned long   d_off;
 129         unsigned short  d_reclen;
 130         char            d_name[1];
 131 };
 132
 133 struct getdents_callback {
 134         struct linux_dirent __user * current_dir;
 135         struct linux_dirent __user * previous;
 136         int count;
 137         int error;
 138 };
 139
 140 static int filldir(void * __buf, const char * name, int namlen, loff_t offset,
 141                    ino_t ino, unsigned int d_type)
 142 {
 143         struct linux_dirent __user * dirent;
 144         struct getdents_callback * buf = (struct getdents_callback *) __buf;
 145         int reclen = ROUND_UP(NAME_OFFSET(dirent) + namlen + 2);
 146
 147         buf->error = -EINVAL;   /* only used if we fail.. */
 148         if (reclen > buf->count)
 149                 return -EINVAL;
 150         dirent = buf->previous;
 151         if (dirent) {
 152                 if (__put_user(offset, &dirent->d_off))
 153                         goto efault;
 154         }
 155         dirent = buf->current_dir;
 156         if (__put_user(ino, &dirent->d_ino))
 157                 goto efault;
 158         if (__put_user(reclen, &dirent->d_reclen))
 159                 goto efault;
 160         if (copy_to_user(dirent->d_name, name, namlen))
 161                 goto efault;
 162         if (__put_user(0, dirent->d_name + namlen))
 163                 goto efault;
 164         if (__put_user(d_type, (char __user *) dirent + reclen - 1))
 165                 goto efault;
 166         buf->previous = dirent;
 167         dirent = (void __user *)dirent + reclen;
 168         buf->current_dir = dirent;
 169         buf->count -= reclen;
 170         return 0;
 171 efault:
 172         buf->error = -EFAULT;
 173         return -EFAULT;
 174 }
 175
 176 asmlinkage long sys_getdents(unsigned int fd, struct linux_dirent __user * dirent, unsigned int count)
 177 {
 178         struct file * file;
 179         struct linux_dirent __user * lastdirent;
 180         struct getdents_callback buf;
 181         int error;
 182
 183         error = -EFAULT;
 184         if (!access_ok(VERIFY_WRITE, dirent, count))
 185                 goto out;
 186
 187         error = -EBADF;
 188         file = fget(fd);
 189         if (!file)
 190                 goto out;
 191
 192         buf.current_dir = dirent;
 193         buf.previous = NULL;
 194         buf.count = count;
 195         buf.error = 0;
 196
 197         error = vfs_readdir(file, filldir, &buf);
 198         if (error < 0)
 199                 goto out_putf;
 200         error = buf.error;
 201         lastdirent = buf.previous;
 202         if (lastdirent) {
 203                 if (put_user(file->f_pos, &lastdirent->d_off))
 204                         error = -EFAULT;
 205                 else
 206                         error = count - buf.count;
 207         }
 208
 209 out_putf:
 210         fput(file);
 211 out:
 212         return error;
 213 }
 214
 215 #define ROUND_UP64(x) (((x)+sizeof(u64)-1) & ~(sizeof(u64)-1))
 216
 217 struct getdents_callback64 {
 218         struct linux_dirent64 __user * current_dir;
 219         struct linux_dirent64 __user * previous;
 220         int count;
 221         int error;
 222 };
 223
 224 static int filldir64(void * __buf, const char * name, int namlen, loff_t offset,
 225                      ino_t ino, unsigned int d_type)
 226 {
 227         struct linux_dirent64 __user *dirent;
 228         struct getdents_callback64 * buf = (struct getdents_callback64 *) __buf;
 229         int reclen = ROUND_UP64(NAME_OFFSET(dirent) + namlen + 1);
 230
 231         buf->error = -EINVAL;   /* only used if we fail.. */
 232         if (reclen > buf->count)
 233                 return -EINVAL;
 234         dirent = buf->previous;
 235         if (dirent) {
 236                 if (__put_user(offset, &dirent->d_off))
 237                         goto efault;
 238         }
 239         dirent = buf->current_dir;
 240         if (__put_user(ino, &dirent->d_ino))
 241                 goto efault;
 242         if (__put_user(0, &dirent->d_off))
 243                 goto efault;
 244         if (__put_user(reclen, &dirent->d_reclen))
 245                 goto efault;
 246         if (__put_user(d_type, &dirent->d_type))
 247                 goto efault;
 248         if (copy_to_user(dirent->d_name, name, namlen))
 249                 goto efault;
 250         if (__put_user(0, dirent->d_name + namlen))
 251                 goto efault;
 252         buf->previous = dirent;
 253         dirent = (void __user *)dirent + reclen;
 254         buf->current_dir = dirent;
 255         buf->count -= reclen;
 256         return 0;
 257 efault:
 258         buf->error = -EFAULT;
 259         return -EFAULT;
 260 }
 261
 262 asmlinkage long sys_getdents64(unsigned int fd, struct linux_dirent64 __user * dirent, unsigned int count)
 263 {
 264         struct file * file;
 265         struct linux_dirent64 __user * lastdirent;
 266         struct getdents_callback64 buf;
 267         int error;
 268
 269         error = -EFAULT;
 270         if (!access_ok(VERIFY_WRITE, dirent, count))
 271                 goto out;
 272
 273         error = -EBADF;
 274         file = fget(fd);
 275         if (!file)
 276                 goto out;
 277
 278         buf.current_dir = dirent;
 279         buf.previous = NULL;
 280         buf.count = count;
 281         buf.error = 0;
 282
 283         error = vfs_readdir(file, filldir64, &buf);
 284         if (error < 0)
 285                 goto out_putf;
 286         error = buf.error;
 287         lastdirent = buf.previous;
 288         if (lastdirent) {
 289                 typeof(lastdirent->d_off) d_off = file->f_pos;
 290                 error = -EFAULT;
 291                 if (__put_user(d_off, &lastdirent->d_off))
 292                         goto out_putf;
 293                 error = count - buf.count;
 294         }
 295
 296 out_putf:
 297         fput(file);
 298 out:
 299         return error;
 300 }