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
  18 #include <asm/uaccess.h>
  19
  20 int vfs_readdir(struct file *file, filldir_t filler, void *buf)
  21 {
  22         struct inode *inode = file->f_dentry->d_inode;
  23         int res = -ENOTDIR;
  24         if (!file->f_op || !file->f_op->readdir)
  25                 goto out;
  26
  27         res = security_file_permission(file, MAY_READ);
  28         if (res)
  29                 goto out;
  30
  31         down(&inode->i_sem);
  32         res = -ENOENT;
  33         if (!IS_DEADDIR(inode)) {
  34                 res = file->f_op->readdir(file, buf, filler);
  35         }
  36         up(&inode->i_sem);
  37 out:
  38         return res;
  39 }
  40
  41 EXPORT_SYMBOL(vfs_readdir);
  42
  43 /*
  44  * Traditional linux readdir() handling..
  45  *
  46  * "count=1" is a special case, meaning that the buffer is one
  47  * dirent-structure in size and that the code can't handle more
  48  * anyway. Thus the special "fillonedir()" function for that
  49  * case (the low-level handlers don't need to care about this).
  50  */
  51 #define NAME_OFFSET(de) ((int) ((de)->d_name - (char *) (de)))
  52 #define ROUND_UP(x) (((x)+sizeof(long)-1) & ~(sizeof(long)-1))
  53
  54 #ifndef __ia64__
  55
  56 struct old_linux_dirent {
  57         unsigned long   d_ino;
  58         unsigned long   d_offset;
  59         unsigned short  d_namlen;
  60         char            d_name[1];
  61 };
  62
  63 struct readdir_callback {
  64         struct old_linux_dirent __user * dirent;
  65         int result;
  66 };
  67
  68 static int fillonedir(void * __buf, const char * name, int namlen, loff_t offset,
  69                       ino_t ino, unsigned int d_type)
  70 {
  71         struct readdir_callback * buf = (struct readdir_callback *) __buf;
  72         struct old_linux_dirent __user * dirent;
  73
  74         if (buf->result)
  75                 return -EINVAL;
  76         buf->result++;
  77         dirent = buf->dirent;
  78         if (!access_ok(VERIFY_WRITE, (unsigned long)dirent,
  79                         (unsigned long)(dirent->d_name + namlen + 1) -
  80                                 (unsigned long)dirent))
  81                 goto efault;
  82         if (    __put_user(ino, &dirent->d_ino) ||
  83                 __put_user(offset, &dirent->d_offset) ||
  84                 __put_user(namlen, &dirent->d_namlen) ||
  85                 __copy_to_user(dirent->d_name, name, namlen) ||
  86                 __put_user(0, dirent->d_name + namlen))
  87                 goto efault;
  88         return 0;
  89 efault:
  90         buf->result = -EFAULT;
  91         return -EFAULT;
  92 }
  93
  94 asmlinkage long old_readdir(unsigned int fd, struct old_linux_dirent __user * dirent, unsigned int count)
  95 {
  96         int error;
  97         struct file * file;
  98         struct readdir_callback buf;
  99
 100         error = -EBADF;
 101         file = fget(fd);
 102         if (!file)
 103                 goto out;
 104
 105         buf.result = 0;
 106         buf.dirent = dirent;
 107
 108         error = vfs_readdir(file, fillonedir, &buf);
 109         if (error >= 0)
 110                 error = buf.result;
 111
 112         fput(file);
 113 out:
 114         return error;
 115 }
 116
 117 #endif /* !__ia64__ */
 118
 119 /*
 120  * New, all-improved, singing, dancing, iBCS2-compliant getdents()
 121  * interface.
 122  */
 123 struct linux_dirent {
 124         unsigned long   d_ino;
 125         unsigned long   d_off;
 126         unsigned short  d_reclen;
 127         char            d_name[1];
 128 };
 129
 130 struct getdents_callback {
 131         struct linux_dirent __user * current_dir;
 132         struct linux_dirent __user * previous;
 133         int count;
 134         int error;
 135 };
 136
 137 static int filldir(void * __buf, const char * name, int namlen, loff_t offset,
 138                    ino_t ino, unsigned int d_type)
 139 {
 140         struct linux_dirent __user * dirent;
 141         struct getdents_callback * buf = (struct getdents_callback *) __buf;
 142         int reclen = ROUND_UP(NAME_OFFSET(dirent) + namlen + 1);
 143
 144         buf->error = -EINVAL;   /* only used if we fail.. */
 145         if (reclen > buf->count)
 146                 return -EINVAL;
 147         dirent = buf->previous;
 148         if (dirent) {
 149                 if (__put_user(offset, &dirent->d_off))
 150                         goto efault;
 151         }
 152         dirent = buf->current_dir;
 153         if (__put_user(ino, &dirent->d_ino))
 154                 goto efault;
 155         if (__put_user(reclen, &dirent->d_reclen))
 156                 goto efault;
 157         if (copy_to_user(dirent->d_name, name, namlen))
 158                 goto efault;
 159         if (__put_user(0, dirent->d_name + namlen))
 160                 goto efault;
 161         buf->previous = dirent;
 162         ((char *) dirent) += reclen;
 163         buf->current_dir = dirent;
 164         buf->count -= reclen;
 165         return 0;
 166 efault:
 167         buf->error = -EFAULT;
 168         return -EFAULT;
 169 }
 170
 171 asmlinkage long sys_getdents(unsigned int fd, struct linux_dirent __user * dirent, unsigned int count)
 172 {
 173         struct file * file;
 174         struct linux_dirent __user * lastdirent;
 175         struct getdents_callback buf;
 176         int error;
 177
 178         error = -EFAULT;
 179         if (!access_ok(VERIFY_WRITE, dirent, count))
 180                 goto out;
 181
 182         error = -EBADF;
 183         file = fget(fd);
 184         if (!file)
 185                 goto out;
 186
 187         buf.current_dir = dirent;
 188         buf.previous = NULL;
 189         buf.count = count;
 190         buf.error = 0;
 191
 192         error = vfs_readdir(file, filldir, &buf);
 193         if (error < 0)
 194                 goto out_putf;
 195         error = buf.error;
 196         lastdirent = buf.previous;
 197         if (lastdirent) {
 198                 if (put_user(file->f_pos, &lastdirent->d_off))
 199                         error = -EFAULT;
 200                 else
 201                         error = count - buf.count;
 202         }
 203
 204 out_putf:
 205         fput(file);
 206 out:
 207         return error;
 208 }
 209
 210 #define ROUND_UP64(x) (((x)+sizeof(u64)-1) & ~(sizeof(u64)-1))
 211
 212 struct getdents_callback64 {
 213         struct linux_dirent64 __user * current_dir;
 214         struct linux_dirent64 __user * previous;
 215         int count;
 216         int error;
 217 };
 218
 219 static int filldir64(void * __buf, const char * name, int namlen, loff_t offset,
 220                      ino_t ino, unsigned int d_type)
 221 {
 222         struct linux_dirent64 __user *dirent;
 223         struct getdents_callback64 * buf = (struct getdents_callback64 *) __buf;
 224         int reclen = ROUND_UP64(NAME_OFFSET(dirent) + namlen + 1);
 225
 226         buf->error = -EINVAL;   /* only used if we fail.. */
 227         if (reclen > buf->count)
 228                 return -EINVAL;
 229         dirent = buf->previous;
 230         if (dirent) {
 231                 if (__put_user(offset, &dirent->d_off))
 232                         goto efault;
 233         }
 234         dirent = buf->current_dir;
 235         if (__put_user(ino, &dirent->d_ino))
 236                 goto efault;
 237         if (__put_user(0, &dirent->d_off))
 238                 goto efault;
 239         if (__put_user(reclen, &dirent->d_reclen))
 240                 goto efault;
 241         if (__put_user(d_type, &dirent->d_type))
 242                 goto efault;
 243         if (copy_to_user(dirent->d_name, name, namlen))
 244                 goto efault;
 245         if (__put_user(0, dirent->d_name + namlen))
 246                 goto efault;
 247         buf->previous = dirent;
 248         ((char *) dirent) += reclen;
 249         buf->current_dir = dirent;
 250         buf->count -= reclen;
 251         return 0;
 252 efault:
 253         buf->error = -EFAULT;
 254         return -EFAULT;
 255 }
 256
 257 asmlinkage long sys_getdents64(unsigned int fd, struct linux_dirent64 __user * dirent, unsigned int count)
 258 {
 259         struct file * file;
 260         struct linux_dirent64 __user * lastdirent;
 261         struct getdents_callback64 buf;
 262         int error;
 263
 264         error = -EFAULT;
 265         if (!access_ok(VERIFY_WRITE, dirent, count))
 266                 goto out;
 267
 268         error = -EBADF;
 269         file = fget(fd);
 270         if (!file)
 271                 goto out;
 272
 273         buf.current_dir = dirent;
 274         buf.previous = NULL;
 275         buf.count = count;
 276         buf.error = 0;
 277
 278         error = vfs_readdir(file, filldir64, &buf);
 279         if (error < 0)
 280                 goto out_putf;
 281         error = buf.error;
 282         lastdirent = buf.previous;
 283         if (lastdirent) {
 284                 typeof(lastdirent->d_off) d_off = file->f_pos;
 285                 __put_user(d_off, &lastdirent->d_off);
 286                 error = count - buf.count;
 287         }
 288
 289 out_putf:
 290         fput(file);
 291 out:
 292         return error;
 293 }