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/module.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
 112        error = -EBADF;
 113        file = fget(fd);
 114        if (!file)
 115                goto out;
 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(file);
 125out:
 126        return error;
 127}
 128
 129#endif /* __ARCH_WANT_OLD_READDIR */
 130
 131/*
 132 * New, all-improved, singing, dancing, iBCS2-compliant getdents()
 133 * interface. 
 134 */
 135struct linux_dirent {
 136        unsigned long   d_ino;
 137        unsigned long   d_off;
 138        unsigned short  d_reclen;
 139        char            d_name[1];
 140};
 141
 142struct getdents_callback {
 143        struct linux_dirent __user * current_dir;
 144        struct linux_dirent __user * previous;
 145        int count;
 146        int error;
 147};
 148
 149static int filldir(void * __buf, const char * name, int namlen, loff_t offset,
 150                   u64 ino, unsigned int d_type)
 151{
 152        struct linux_dirent __user * dirent;
 153        struct getdents_callback * buf = (struct getdents_callback *) __buf;
 154        unsigned long d_ino;
 155        int reclen = ALIGN(offsetof(struct linux_dirent, d_name) + namlen + 2,
 156                sizeof(long));
 157
 158        buf->error = -EINVAL;   /* only used if we fail.. */
 159        if (reclen > buf->count)
 160                return -EINVAL;
 161        d_ino = ino;
 162        if (sizeof(d_ino) < sizeof(ino) && d_ino != ino) {
 163                buf->error = -EOVERFLOW;
 164                return -EOVERFLOW;
 165        }
 166        dirent = buf->previous;
 167        if (dirent) {
 168                if (__put_user(offset, &dirent->d_off))
 169                        goto efault;
 170        }
 171        dirent = buf->current_dir;
 172        if (__put_user(d_ino, &dirent->d_ino))
 173                goto efault;
 174        if (__put_user(reclen, &dirent->d_reclen))
 175                goto efault;
 176        if (copy_to_user(dirent->d_name, name, namlen))
 177                goto efault;
 178        if (__put_user(0, dirent->d_name + namlen))
 179                goto efault;
 180        if (__put_user(d_type, (char __user *) dirent + reclen - 1))
 181                goto efault;
 182        buf->previous = dirent;
 183        dirent = (void __user *)dirent + reclen;
 184        buf->current_dir = dirent;
 185        buf->count -= reclen;
 186        return 0;
 187efault:
 188        buf->error = -EFAULT;
 189        return -EFAULT;
 190}
 191
 192SYSCALL_DEFINE3(getdents, unsigned int, fd,
 193                struct linux_dirent __user *, dirent, unsigned int, count)
 194{
 195        struct file * file;
 196        struct linux_dirent __user * lastdirent;
 197        struct getdents_callback buf;
 198        int error;
 199
 200        error = -EFAULT;
 201        if (!access_ok(VERIFY_WRITE, dirent, count))
 202                goto out;
 203
 204        error = -EBADF;
 205        file = fget(fd);
 206        if (!file)
 207                goto out;
 208
 209        buf.current_dir = dirent;
 210        buf.previous = NULL;
 211        buf.count = count;
 212        buf.error = 0;
 213
 214        error = vfs_readdir(file, filldir, &buf);
 215        if (error >= 0)
 216                error = buf.error;
 217        lastdirent = buf.previous;
 218        if (lastdirent) {
 219                if (put_user(file->f_pos, &lastdirent->d_off))
 220                        error = -EFAULT;
 221                else
 222                        error = count - buf.count;
 223        }
 224        fput(file);
 225out:
 226        return error;
 227}
 228
 229struct getdents_callback64 {
 230        struct linux_dirent64 __user * current_dir;
 231        struct linux_dirent64 __user * previous;
 232        int count;
 233        int error;
 234};
 235
 236static int filldir64(void * __buf, const char * name, int namlen, loff_t offset,
 237                     u64 ino, unsigned int d_type)
 238{
 239        struct linux_dirent64 __user *dirent;
 240        struct getdents_callback64 * buf = (struct getdents_callback64 *) __buf;
 241        int reclen = ALIGN(offsetof(struct linux_dirent64, d_name) + namlen + 1,
 242                sizeof(u64));
 243
 244        buf->error = -EINVAL;   /* only used if we fail.. */
 245        if (reclen > buf->count)
 246                return -EINVAL;
 247        dirent = buf->previous;
 248        if (dirent) {
 249                if (__put_user(offset, &dirent->d_off))
 250                        goto efault;
 251        }
 252        dirent = buf->current_dir;
 253        if (__put_user(ino, &dirent->d_ino))
 254                goto efault;
 255        if (__put_user(0, &dirent->d_off))
 256                goto efault;
 257        if (__put_user(reclen, &dirent->d_reclen))
 258                goto efault;
 259        if (__put_user(d_type, &dirent->d_type))
 260                goto efault;
 261        if (copy_to_user(dirent->d_name, name, namlen))
 262                goto efault;
 263        if (__put_user(0, dirent->d_name + namlen))
 264                goto efault;
 265        buf->previous = dirent;
 266        dirent = (void __user *)dirent + reclen;
 267        buf->current_dir = dirent;
 268        buf->count -= reclen;
 269        return 0;
 270efault:
 271        buf->error = -EFAULT;
 272        return -EFAULT;
 273}
 274
 275SYSCALL_DEFINE3(getdents64, unsigned int, fd,
 276                struct linux_dirent64 __user *, dirent, unsigned int, count)
 277{
 278        struct file * file;
 279        struct linux_dirent64 __user * lastdirent;
 280        struct getdents_callback64 buf;
 281        int error;
 282
 283        error = -EFAULT;
 284        if (!access_ok(VERIFY_WRITE, dirent, count))
 285                goto out;
 286
 287        error = -EBADF;
 288        file = fget(fd);
 289        if (!file)
 290                goto out;
 291
 292        buf.current_dir = dirent;
 293        buf.previous = NULL;
 294        buf.count = count;
 295        buf.error = 0;
 296
 297        error = vfs_readdir(file, filldir64, &buf);
 298        if (error >= 0)
 299                error = buf.error;
 300        lastdirent = buf.previous;
 301        if (lastdirent) {
 302                typeof(lastdirent->d_off) d_off = file->f_pos;
 303                if (__put_user(d_off, &lastdirent->d_off))
 304                        error = -EFAULT;
 305                else
 306                        error = count - buf.count;
 307        }
 308        fput(file);
 309out:
 310        return error;
 311}
 312
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