fs/readdir.c

   1 /*
   2  *  linux/fs/readdir.c
   3  *
   4  *  Copyright (C) 1995  Linus Torvalds
   5  */
   6
   7 #include <linux/time.h>
   8 #include <linux/mm.h>
   9 #include <linux/errno.h>
  10 #include <linux/stat.h>
  11 #include <linux/file.h>
  12 #include <linux/smp_lock.h>
  13 #include <linux/fs.h>
  14 #include <linux/dirent.h>
  15 #include <linux/security.h>
  16
  17 #include <asm/uaccess.h>
  18
  19 int vfs_readdir(struct file *file, filldir_t filler, void *buf)
  20 {
  21         struct inode *inode = file->f_dentry->d_inode;
  22         int res = -ENOTDIR;
  23         if (!file->f_op || !file->f_op->readdir)
  24                 goto out;
  25
  26         res = security_file_permission(file, MAY_READ);
  27         if (res)
  28                 goto out;
  29
  30         down(&inode->i_sem);
  31         res = -ENOENT;
  32         if (!IS_DEADDIR(inode)) {
  33                 res = file->f_op->readdir(file, buf, filler);
  34         }
  35         up(&inode->i_sem);
  36 out:
  37         return res;
  38 }
  39
  40 /*
  41  * Traditional linux readdir() handling..
  42  *
  43  * "count=1" is a special case, meaning that the buffer is one
  44  * dirent-structure in size and that the code can't handle more
  45  * anyway. Thus the special "fillonedir()" function for that
  46  * case (the low-level handlers don't need to care about this).
  47  */
  48 #define NAME_OFFSET(de) ((int) ((de)->d_name - (char *) (de)))
  49 #define ROUND_UP(x) (((x)+sizeof(long)-1) & ~(sizeof(long)-1))
  50
  51 #ifndef __ia64__
  52
  53 struct old_linux_dirent {
  54         unsigned long   d_ino;
  55         unsigned long   d_offset;
  56         unsigned short  d_namlen;
  57         char            d_name[1];
  58 };
  59
  60 struct readdir_callback {
  61         struct old_linux_dirent __user * dirent;
  62         int result;
  63 };
  64
  65 static int fillonedir(void * __buf, const char * name, int namlen, loff_t offset,
  66                       ino_t ino, unsigned int d_type)
  67 {
  68         struct readdir_callback * buf = (struct readdir_callback *) __buf;
  69         struct old_linux_dirent __user * dirent;
  70
  71         if (buf->result)
  72                 return -EINVAL;
  73         buf->result++;
  74         dirent = buf->dirent;
  75         if (!access_ok(VERIFY_WRITE, (unsigned long)dirent,
  76                         (unsigned long)(dirent->d_name + namlen + 1) -
  77                                 (unsigned long)dirent))
  78                 goto efault;
  79         if (    __put_user(ino, &dirent->d_ino) ||
  80                 __put_user(offset, &dirent->d_offset) ||
  81                 __put_user(namlen, &dirent->d_namlen) ||
  82                 __copy_to_user(dirent->d_name, name, namlen) ||
  83                 __put_user(0, dirent->d_name + namlen))
  84                 goto efault;
  85         return 0;
  86 efault:
  87         buf->result = -EFAULT;
  88         return -EFAULT;
  89 }
  90
  91 asmlinkage long old_readdir(unsigned int fd, struct old_linux_dirent __user * dirent, unsigned int count)
  92 {
  93         int error;
  94         struct file * file;
  95         struct readdir_callback buf;
  96
  97         error = -EBADF;
  98         file = fget(fd);
  99         if (!file)
 100                 goto out;
 101
 102         buf.result = 0;
 103         buf.dirent = dirent;
 104
 105         error = vfs_readdir(file, fillonedir, &buf);
 106         if (error >= 0)
 107                 error = buf.result;
 108
 109         fput(file);
 110 out:
 111         return error;
 112 }
 113
 114 #endif /* !__ia64__ */
 115
 116 /*
 117  * New, all-improved, singing, dancing, iBCS2-compliant getdents()
 118  * interface.
 119  */
 120 struct linux_dirent {
 121         unsigned long   d_ino;
 122         unsigned long   d_off;
 123         unsigned short  d_reclen;
 124         char            d_name[1];
 125 };
 126
 127 struct getdents_callback {
 128         struct linux_dirent __user * current_dir;
 129         struct linux_dirent __user * previous;
 130         int count;
 131         int error;
 132 };
 133
 134 static int filldir(void * __buf, const char * name, int namlen, loff_t offset,
 135                    ino_t ino, unsigned int d_type)
 136 {
 137         struct linux_dirent __user * dirent;
 138         struct getdents_callback * buf = (struct getdents_callback *) __buf;
 139         int reclen = ROUND_UP(NAME_OFFSET(dirent) + namlen + 1);
 140
 141         buf->error = -EINVAL;   /* only used if we fail.. */
 142         if (reclen > buf->count)
 143                 return -EINVAL;
 144         dirent = buf->previous;
 145         if (dirent) {
 146                 if (__put_user(offset, &dirent->d_off))
 147                         goto efault;
 148         }
 149         dirent = buf->current_dir;
 150         if (__put_user(ino, &dirent->d_ino))
 151                 goto efault;
 152         if (__put_user(reclen, &dirent->d_reclen))
 153                 goto efault;
 154         if (copy_to_user(dirent->d_name, name, namlen))
 155                 goto efault;
 156         if (__put_user(0, dirent->d_name + namlen))
 157                 goto efault;
 158         buf->previous = dirent;
 159         ((char *) dirent) += reclen;
 160         buf->current_dir = dirent;
 161         buf->count -= reclen;
 162         return 0;
 163 efault:
 164         buf->error = -EFAULT;
 165         return -EFAULT;
 166 }
 167
 168 asmlinkage long sys_getdents(unsigned int fd, struct linux_dirent __user * dirent, unsigned int count)
 169 {
 170         struct file * file;
 171         struct linux_dirent __user * lastdirent;
 172         struct getdents_callback buf;
 173         int error;
 174
 175         error = -EFAULT;
 176         if (!access_ok(VERIFY_WRITE, dirent, count))
 177                 goto out;
 178
 179         error = -EBADF;
 180         file = fget(fd);
 181         if (!file)
 182                 goto out;
 183
 184         buf.current_dir = dirent;
 185         buf.previous = NULL;
 186         buf.count = count;
 187         buf.error = 0;
 188
 189         error = vfs_readdir(file, filldir, &buf);
 190         if (error < 0)
 191                 goto out_putf;
 192         error = buf.error;
 193         lastdirent = buf.previous;
 194         if (lastdirent) {
 195                 if (put_user(file->f_pos, &lastdirent->d_off))
 196                         error = -EFAULT;
 197                 else
 198                         error = count - buf.count;
 199         }
 200
 201 out_putf:
 202         fput(file);
 203 out:
 204         return error;
 205 }
 206
 207 #define ROUND_UP64(x) (((x)+sizeof(u64)-1) & ~(sizeof(u64)-1))
 208
 209 struct getdents_callback64 {
 210         struct linux_dirent64 __user * current_dir;
 211         struct linux_dirent64 __user * previous;
 212         int count;
 213         int error;
 214 };
 215
 216 static int filldir64(void * __buf, const char * name, int namlen, loff_t offset,
 217                      ino_t ino, unsigned int d_type)
 218 {
 219         struct linux_dirent64 __user *dirent;
 220         struct getdents_callback64 * buf = (struct getdents_callback64 *) __buf;
 221         int reclen = ROUND_UP64(NAME_OFFSET(dirent) + namlen + 1);
 222
 223         buf->error = -EINVAL;   /* only used if we fail.. */
 224         if (reclen > buf->count)
 225                 return -EINVAL;
 226         dirent = buf->previous;
 227         if (dirent) {
 228                 if (__put_user(offset, &dirent->d_off))
 229                         goto efault;
 230         }
 231         dirent = buf->current_dir;
 232         if (__put_user(ino, &dirent->d_ino))
 233                 goto efault;
 234         if (__put_user(0, &dirent->d_off))
 235                 goto efault;
 236         if (__put_user(reclen, &dirent->d_reclen))
 237                 goto efault;
 238         if (__put_user(d_type, &dirent->d_type))
 239                 goto efault;
 240         if (copy_to_user(dirent->d_name, name, namlen))
 241                 goto efault;
 242         if (__put_user(0, dirent->d_name + namlen))
 243                 goto efault;
 244         buf->previous = dirent;
 245         ((char *) dirent) += reclen;
 246         buf->current_dir = dirent;
 247         buf->count -= reclen;
 248         return 0;
 249 efault:
 250         buf->error = -EFAULT;
 251         return -EFAULT;
 252 }
 253
 254 asmlinkage long sys_getdents64(unsigned int fd, struct linux_dirent64 __user * dirent, unsigned int count)
 255 {
 256         struct file * file;
 257         struct linux_dirent64 __user * lastdirent;
 258         struct getdents_callback64 buf;
 259         int error;
 260
 261         error = -EFAULT;
 262         if (!access_ok(VERIFY_WRITE, dirent, count))
 263                 goto out;
 264
 265         error = -EBADF;
 266         file = fget(fd);
 267         if (!file)
 268                 goto out;
 269
 270         buf.current_dir = dirent;
 271         buf.previous = NULL;
 272         buf.count = count;
 273         buf.error = 0;
 274
 275         error = vfs_readdir(file, filldir64, &buf);
 276         if (error < 0)
 277                 goto out_putf;
 278         error = buf.error;
 279         lastdirent = buf.previous;
 280         if (lastdirent) {
 281                 typeof(lastdirent->d_off) d_off = file->f_pos;
 282                 __put_user(d_off, &lastdirent->d_off);
 283                 error = count - buf.count;
 284         }
 285
 286 out_putf:
 287         fput(file);
 288 out:
 289         return error;
 290 }