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                 file_accessed(file);
  36         }
  37         up(&inode->i_sem);
  38 out:
  39         return res;
  40 }
  41
  42 EXPORT_SYMBOL(vfs_readdir);
  43
  44 /*
  45  * Traditional linux readdir() handling..
  46  *
  47  * "count=1" is a special case, meaning that the buffer is one
  48  * dirent-structure in size and that the code can't handle more
  49  * anyway. Thus the special "fillonedir()" function for that
  50  * case (the low-level handlers don't need to care about this).
  51  */
  52 #define NAME_OFFSET(de) ((int) ((de)->d_name - (char *) (de)))
  53 #define ROUND_UP(x) (((x)+sizeof(long)-1) & ~(sizeof(long)-1))
  54
  55 #ifndef __ia64__
  56
  57 struct old_linux_dirent {
  58         unsigned long   d_ino;
  59         unsigned long   d_offset;
  60         unsigned short  d_namlen;
  61         char            d_name[1];
  62 };
  63
  64 struct readdir_callback {
  65         struct old_linux_dirent __user * dirent;
  66         int result;
  67 };
  68
  69 static int fillonedir(void * __buf, const char * name, int namlen, loff_t offset,
  70                       ino_t ino, unsigned int d_type)
  71 {
  72         struct readdir_callback * buf = (struct readdir_callback *) __buf;
  73         struct old_linux_dirent __user * dirent;
  74
  75         if (buf->result)
  76                 return -EINVAL;
  77         buf->result++;
  78         dirent = buf->dirent;
  79         if (!access_ok(VERIFY_WRITE, (unsigned long)dirent,
  80                         (unsigned long)(dirent->d_name + namlen + 1) -
  81                                 (unsigned long)dirent))
  82                 goto efault;
  83         if (    __put_user(ino, &dirent->d_ino) ||
  84                 __put_user(offset, &dirent->d_offset) ||
  85                 __put_user(namlen, &dirent->d_namlen) ||
  86                 __copy_to_user(dirent->d_name, name, namlen) ||
  87                 __put_user(0, dirent->d_name + namlen))
  88                 goto efault;
  89         return 0;
  90 efault:
  91         buf->result = -EFAULT;
  92         return -EFAULT;
  93 }
  94
  95 asmlinkage long old_readdir(unsigned int fd, struct old_linux_dirent __user * dirent, unsigned int count)
  96 {
  97         int error;
  98         struct file * file;
  99         struct readdir_callback buf;
 100
 101         error = -EBADF;
 102         file = fget(fd);
 103         if (!file)
 104                 goto out;
 105
 106         buf.result = 0;
 107         buf.dirent = dirent;
 108
 109         error = vfs_readdir(file, fillonedir, &buf);
 110         if (error >= 0)
 111                 error = buf.result;
 112
 113         fput(file);
 114 out:
 115         return error;
 116 }
 117
 118 #endif /* !__ia64__ */
 119
 120 /*
 121  * New, all-improved, singing, dancing, iBCS2-compliant getdents()
 122  * interface.
 123  */
 124 struct linux_dirent {
 125         unsigned long   d_ino;
 126         unsigned long   d_off;
 127         unsigned short  d_reclen;
 128         char            d_name[1];
 129 };
 130
 131 struct getdents_callback {
 132         struct linux_dirent __user * current_dir;
 133         struct linux_dirent __user * previous;
 134         int count;
 135         int error;
 136 };
 137
 138 static int filldir(void * __buf, const char * name, int namlen, loff_t offset,
 139                    ino_t ino, unsigned int d_type)
 140 {
 141         struct linux_dirent __user * dirent;
 142         struct getdents_callback * buf = (struct getdents_callback *) __buf;
 143         int reclen = ROUND_UP(NAME_OFFSET(dirent) + namlen + 2);
 144
 145         buf->error = -EINVAL;   /* only used if we fail.. */
 146         if (reclen > buf->count)
 147                 return -EINVAL;
 148         dirent = buf->previous;
 149         if (dirent) {
 150                 if (__put_user(offset, &dirent->d_off))
 151                         goto efault;
 152         }
 153         dirent = buf->current_dir;
 154         if (__put_user(ino, &dirent->d_ino))
 155                 goto efault;
 156         if (__put_user(reclen, &dirent->d_reclen))
 157                 goto efault;
 158         if (copy_to_user(dirent->d_name, name, namlen))
 159                 goto efault;
 160         if (__put_user(0, dirent->d_name + namlen))
 161                 goto efault;
 162         if (__put_user(d_type, (char *) dirent + reclen - 1))
 163                 goto efault;
 164         buf->previous = dirent;
 165         dirent = (void __user *)dirent + reclen;
 166         buf->current_dir = dirent;
 167         buf->count -= reclen;
 168         return 0;
 169 efault:
 170         buf->error = -EFAULT;
 171         return -EFAULT;
 172 }
 173
 174 asmlinkage long sys_getdents(unsigned int fd, struct linux_dirent __user * dirent, unsigned int count)
 175 {
 176         struct file * file;
 177         struct linux_dirent __user * lastdirent;
 178         struct getdents_callback buf;
 179         int error;
 180
 181         error = -EFAULT;
 182         if (!access_ok(VERIFY_WRITE, dirent, count))
 183                 goto out;
 184
 185         error = -EBADF;
 186         file = fget(fd);
 187         if (!file)
 188                 goto out;
 189
 190         buf.current_dir = dirent;
 191         buf.previous = NULL;
 192         buf.count = count;
 193         buf.error = 0;
 194
 195         error = vfs_readdir(file, filldir, &buf);
 196         if (error < 0)
 197                 goto out_putf;
 198         error = buf.error;
 199         lastdirent = buf.previous;
 200         if (lastdirent) {
 201                 if (put_user(file->f_pos, &lastdirent->d_off))
 202                         error = -EFAULT;
 203                 else
 204                         error = count - buf.count;
 205         }
 206
 207 out_putf:
 208         fput(file);
 209 out:
 210         return error;
 211 }
 212
 213 #define ROUND_UP64(x) (((x)+sizeof(u64)-1) & ~(sizeof(u64)-1))
 214
 215 struct getdents_callback64 {
 216         struct linux_dirent64 __user * current_dir;
 217         struct linux_dirent64 __user * previous;
 218         int count;
 219         int error;
 220 };
 221
 222 static int filldir64(void * __buf, const char * name, int namlen, loff_t offset,
 223                      ino_t ino, unsigned int d_type)
 224 {
 225         struct linux_dirent64 __user *dirent;
 226         struct getdents_callback64 * buf = (struct getdents_callback64 *) __buf;
 227         int reclen = ROUND_UP64(NAME_OFFSET(dirent) + namlen + 1);
 228
 229         buf->error = -EINVAL;   /* only used if we fail.. */
 230         if (reclen > buf->count)
 231                 return -EINVAL;
 232         dirent = buf->previous;
 233         if (dirent) {
 234                 if (__put_user(offset, &dirent->d_off))
 235                         goto efault;
 236         }
 237         dirent = buf->current_dir;
 238         if (__put_user(ino, &dirent->d_ino))
 239                 goto efault;
 240         if (__put_user(0, &dirent->d_off))
 241                 goto efault;
 242         if (__put_user(reclen, &dirent->d_reclen))
 243                 goto efault;
 244         if (__put_user(d_type, &dirent->d_type))
 245                 goto efault;
 246         if (copy_to_user(dirent->d_name, name, namlen))
 247                 goto efault;
 248         if (__put_user(0, dirent->d_name + namlen))
 249                 goto efault;
 250         buf->previous = dirent;
 251         dirent = (void __user *)dirent + reclen;
 252         buf->current_dir = dirent;
 253         buf->count -= reclen;
 254         return 0;
 255 efault:
 256         buf->error = -EFAULT;
 257         return -EFAULT;
 258 }
 259
 260 asmlinkage long sys_getdents64(unsigned int fd, struct linux_dirent64 __user * dirent, unsigned int count)
 261 {
 262         struct file * file;
 263         struct linux_dirent64 __user * lastdirent;
 264         struct getdents_callback64 buf;
 265         int error;
 266
 267         error = -EFAULT;
 268         if (!access_ok(VERIFY_WRITE, dirent, count))
 269                 goto out;
 270
 271         error = -EBADF;
 272         file = fget(fd);
 273         if (!file)
 274                 goto out;
 275
 276         buf.current_dir = dirent;
 277         buf.previous = NULL;
 278         buf.count = count;
 279         buf.error = 0;
 280
 281         error = vfs_readdir(file, filldir64, &buf);
 282         if (error < 0)
 283                 goto out_putf;
 284         error = buf.error;
 285         lastdirent = buf.previous;
 286         if (lastdirent) {
 287                 typeof(lastdirent->d_off) d_off = file->f_pos;
 288                 __put_user(d_off, &lastdirent->d_off);
 289                 error = count - buf.count;
 290         }
 291
 292 out_putf:
 293         fput(file);
 294 out:
 295         return error;
 296 }