linux/fs/readdir.c
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   1/*
   2 *  linux/fs/readdir.c
   3 *
   4 *  Copyright (C) 1995  Linus Torvalds
   5 */
   6
   7#include <linux/stddef.h>
   8#include <linux/kernel.h>
   9#include <linux/export.h>
  10#include <linux/time.h>
  11#include <linux/mm.h>
  12#include <linux/errno.h>
  13#include <linux/stat.h>
  14#include <linux/file.h>
  15#include <linux/fs.h>
  16#include <linux/dirent.h>
  17#include <linux/security.h>
  18#include <linux/syscalls.h>
  19#include <linux/unistd.h>
  20
  21#include <asm/uaccess.h>
  22
  23int vfs_readdir(struct file *file, filldir_t filler, void *buf)
  24{
  25        struct inode *inode = file->f_path.dentry->d_inode;
  26        int res = -ENOTDIR;
  27        if (!file->f_op || !file->f_op->readdir)
  28                goto out;
  29
  30        res = security_file_permission(file, MAY_READ);
  31        if (res)
  32                goto out;
  33
  34        res = mutex_lock_killable(&inode->i_mutex);
  35        if (res)
  36                goto out;
  37
  38        res = -ENOENT;
  39        if (!IS_DEADDIR(inode)) {
  40                res = file->f_op->readdir(file, buf, filler);
  41                file_accessed(file);
  42        }
  43        mutex_unlock(&inode->i_mutex);
  44out:
  45        return res;
  46}
  47
  48EXPORT_SYMBOL(vfs_readdir);
  49
  50/*
  51 * Traditional linux readdir() handling..
  52 *
  53 * "count=1" is a special case, meaning that the buffer is one
  54 * dirent-structure in size and that the code can't handle more
  55 * anyway. Thus the special "fillonedir()" function for that
  56 * case (the low-level handlers don't need to care about this).
  57 */
  58
  59#ifdef __ARCH_WANT_OLD_READDIR
  60
  61struct old_linux_dirent {
  62        unsigned long   d_ino;
  63        unsigned long   d_offset;
  64        unsigned short  d_namlen;
  65        char            d_name[1];
  66};
  67
  68struct readdir_callback {
  69        struct old_linux_dirent __user * dirent;
  70        int result;
  71};
  72
  73static int fillonedir(void * __buf, const char * name, int namlen, loff_t offset,
  74                      u64 ino, unsigned int d_type)
  75{
  76        struct readdir_callback * buf = (struct readdir_callback *) __buf;
  77        struct old_linux_dirent __user * dirent;
  78        unsigned long d_ino;
  79
  80        if (buf->result)
  81                return -EINVAL;
  82        d_ino = ino;
  83        if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
  84                buf->result = -EOVERFLOW;
  85                return -EOVERFLOW;
  86        }
  87        buf->result++;
  88        dirent = buf->dirent;
  89        if (!access_ok(VERIFY_WRITE, dirent,
  90                        (unsigned long)(dirent->d_name + namlen + 1) -
  91                                (unsigned long)dirent))
  92                goto efault;
  93        if (    __put_user(d_ino, &dirent->d_ino) ||
  94                __put_user(offset, &dirent->d_offset) ||
  95                __put_user(namlen, &dirent->d_namlen) ||
  96                __copy_to_user(dirent->d_name, name, namlen) ||
  97                __put_user(0, dirent->d_name + namlen))
  98                goto efault;
  99        return 0;
 100efault:
 101        buf->result = -EFAULT;
 102        return -EFAULT;
 103}
 104
 105SYSCALL_DEFINE3(old_readdir, unsigned int, fd,
 106                struct old_linux_dirent __user *, dirent, unsigned int, count)
 107{
 108        int error;
 109        struct file * file;
 110        struct readdir_callback buf;
 111        int fput_needed;
 112
 113        file = fget_light(fd, &fput_needed);
 114        if (!file)
 115                return -EBADF;
 116
 117        buf.result = 0;
 118        buf.dirent = dirent;
 119
 120        error = vfs_readdir(file, fillonedir, &buf);
 121        if (buf.result)
 122                error = buf.result;
 123
 124        fput_light(file, fput_needed);
 125        return error;
 126}
 127
 128#endif /* __ARCH_WANT_OLD_READDIR */
 129
 130/*
 131 * New, all-improved, singing, dancing, iBCS2-compliant getdents()
 132 * interface. 
 133 */
 134struct linux_dirent {
 135        unsigned long   d_ino;
 136        unsigned long   d_off;
 137        unsigned short  d_reclen;
 138        char            d_name[1];
 139};
 140
 141struct getdents_callback {
 142        struct linux_dirent __user * current_dir;
 143        struct linux_dirent __user * previous;
 144        int count;
 145        int error;
 146};
 147
 148static int filldir(void * __buf, const char * name, int namlen, loff_t offset,
 149                   u64 ino, unsigned int d_type)
 150{
 151        struct linux_dirent __user * dirent;
 152        struct getdents_callback * buf = (struct getdents_callback *) __buf;
 153        unsigned long d_ino;
 154        int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2,
 155                sizeof(long));
 156
 157        buf->error = -EINVAL;   /* only used if we fail.. */
 158        if (reclen > buf->count)
 159                return -EINVAL;
 160        d_ino = ino;
 161        if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
 162                buf->error = -EOVERFLOW;
 163                return -EOVERFLOW;
 164        }
 165        dirent = buf->previous;
 166        if (dirent) {
 167                if (__put_user(offset, &dirent->d_off))
 168                        goto efault;
 169        }
 170        dirent = buf->current_dir;
 171        if (__put_user(d_ino, &dirent->d_ino))
 172                goto efault;
 173        if (__put_user(reclen, &dirent->d_reclen))
 174                goto efault;
 175        if (copy_to_user(dirent->d_name, name, namlen))
 176                goto efault;
 177        if (__put_user(0, dirent->d_name + namlen))
 178                goto efault;
 179        if (__put_user(d_type, (char __user *) dirent + reclen - 1))
 180                goto efault;
 181        buf->previous = dirent;
 182        dirent = (void __user *)dirent + reclen;
 183        buf->current_dir = dirent;
 184        buf->count -= reclen;
 185        return 0;
 186efault:
 187        buf->error = -EFAULT;
 188        return -EFAULT;
 189}
 190
 191SYSCALL_DEFINE3(getdents, unsigned int, fd,
 192                struct linux_dirent __user *, dirent, unsigned int, count)
 193{
 194        struct file * file;
 195        struct linux_dirent __user * lastdirent;
 196        struct getdents_callback buf;
 197        int fput_needed;
 198        int error;
 199
 200        if (!access_ok(VERIFY_WRITE, dirent, count))
 201                return -EFAULT;
 202
 203        file = fget_light(fd, &fput_needed);
 204        if (!file)
 205                return -EBADF;
 206
 207        buf.current_dir = dirent;
 208        buf.previous = NULL;
 209        buf.count = count;
 210        buf.error = 0;
 211
 212        error = vfs_readdir(file, filldir, &buf);
 213        if (error >= 0)
 214                error = buf.error;
 215        lastdirent = buf.previous;
 216        if (lastdirent) {
 217                if (put_user(file->f_pos, &lastdirent->d_off))
 218                        error = -EFAULT;
 219                else
 220                        error = count - buf.count;
 221        }
 222        fput_light(file, fput_needed);
 223        return error;
 224}
 225
 226struct getdents_callback64 {
 227        struct linux_dirent64 __user * current_dir;
 228        struct linux_dirent64 __user * previous;
 229        int count;
 230        int error;
 231};
 232
 233static int filldir64(void * __buf, const char * name, int namlen, loff_t offset,
 234                     u64 ino, unsigned int d_type)
 235{
 236        struct linux_dirent64 __user *dirent;
 237        struct getdents_callback64 * buf = (struct getdents_callback64 *) __buf;
 238        int reclen = ALIGN(offsetof(struct linux_dirent64, d_name) + namlen + 1,
 239                sizeof(u64));
 240
 241        buf->error = -EINVAL;   /* only used if we fail.. */
 242        if (reclen > buf->count)
 243                return -EINVAL;
 244        dirent = buf->previous;
 245        if (dirent) {
 246                if (__put_user(offset, &dirent->d_off))
 247                        goto efault;
 248        }
 249        dirent = buf->current_dir;
 250        if (__put_user(ino, &dirent->d_ino))
 251                goto efault;
 252        if (__put_user(0, &dirent->d_off))
 253                goto efault;
 254        if (__put_user(reclen, &dirent->d_reclen))
 255                goto efault;
 256        if (__put_user(d_type, &dirent->d_type))
 257                goto efault;
 258        if (copy_to_user(dirent->d_name, name, namlen))
 259                goto efault;
 260        if (__put_user(0, dirent->d_name + namlen))
 261                goto efault;
 262        buf->previous = dirent;
 263        dirent = (void __user *)dirent + reclen;
 264        buf->current_dir = dirent;
 265        buf->count -= reclen;
 266        return 0;
 267efault:
 268        buf->error = -EFAULT;
 269        return -EFAULT;
 270}
 271
 272SYSCALL_DEFINE3(getdents64, unsigned int, fd,
 273                struct linux_dirent64 __user *, dirent, unsigned int, count)
 274{
 275        struct file * file;
 276        struct linux_dirent64 __user * lastdirent;
 277        struct getdents_callback64 buf;
 278        int fput_needed;
 279        int error;
 280
 281        if (!access_ok(VERIFY_WRITE, dirent, count))
 282                return -EFAULT;
 283
 284        file = fget_light(fd, &fput_needed);
 285        if (!file)
 286                return -EBADF;
 287
 288        buf.current_dir = dirent;
 289        buf.previous = NULL;
 290        buf.count = count;
 291        buf.error = 0;
 292
 293        error = vfs_readdir(file, filldir64, &buf);
 294        if (error >= 0)
 295                error = buf.error;
 296        lastdirent = buf.previous;
 297        if (lastdirent) {
 298                typeof(lastdirent->d_off) d_off = file->f_pos;
 299                if (__put_user(d_off, &lastdirent->d_off))
 300                        error = -EFAULT;
 301                else
 302                        error = count - buf.count;
 303        }
 304        fput_light(file, fput_needed);
 305        return error;
 306}
 307
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