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
  15 #include <asm/uaccess.h>
  16
  17 int vfs_readdir(struct file *file, filldir_t filler, void *buf)
  18 {
  19         struct inode *inode = file->f_dentry->d_inode;
  20         int res = -ENOTDIR;
  21         if (!file->f_op || !file->f_op->readdir)
  22                 goto out;
  23
  24         res = security_ops->file_permission(file, MAY_READ);
  25         if (res)
  26                 goto out;
  27
  28         down(&inode->i_sem);
  29         res = -ENOENT;
  30         if (!IS_DEADDIR(inode)) {
  31                 res = file->f_op->readdir(file, buf, filler);
  32         }
  33         up(&inode->i_sem);
  34 out:
  35         return res;
  36 }
  37
  38 /*
  39  * Traditional linux readdir() handling..
  40  *
  41  * "count=1" is a special case, meaning that the buffer is one
  42  * dirent-structure in size and that the code can't handle more
  43  * anyway. Thus the special "fillonedir()" function for that
  44  * case (the low-level handlers don't need to care about this).
  45  */
  46 #define NAME_OFFSET(de) ((int) ((de)->d_name - (char *) (de)))
  47 #define ROUND_UP(x) (((x)+sizeof(long)-1) & ~(sizeof(long)-1))
  48
  49 #ifndef __ia64__
  50
  51 struct old_linux_dirent {
  52         unsigned long   d_ino;
  53         unsigned long   d_offset;
  54         unsigned short  d_namlen;
  55         char            d_name[1];
  56 };
  57
  58 struct readdir_callback {
  59         struct old_linux_dirent * dirent;
  60         int count;
  61 };
  62
  63 static int fillonedir(void * __buf, const char * name, int namlen, loff_t offset,
  64                       ino_t ino, unsigned int d_type)
  65 {
  66         struct readdir_callback * buf = (struct readdir_callback *) __buf;
  67         struct old_linux_dirent * dirent;
  68
  69         if (buf->count)
  70                 return -EINVAL;
  71         buf->count++;
  72         dirent = buf->dirent;
  73         put_user(ino, &dirent->d_ino);
  74         put_user(offset, &dirent->d_offset);
  75         put_user(namlen, &dirent->d_namlen);
  76         copy_to_user(dirent->d_name, name, namlen);
  77         put_user(0, dirent->d_name + namlen);
  78         return 0;
  79 }
  80
  81 asmlinkage int old_readdir(unsigned int fd, void * dirent, unsigned int count)
  82 {
  83         int error;
  84         struct file * file;
  85         struct readdir_callback buf;
  86
  87         error = -EBADF;
  88         file = fget(fd);
  89         if (!file)
  90                 goto out;
  91
  92         buf.count = 0;
  93         buf.dirent = dirent;
  94
  95         error = vfs_readdir(file, fillonedir, &buf);
  96         if (error >= 0)
  97                 error = buf.count;
  98
  99         fput(file);
 100 out:
 101         return error;
 102 }
 103
 104 #endif /* !__ia64__ */
 105
 106 /*
 107  * New, all-improved, singing, dancing, iBCS2-compliant getdents()
 108  * interface.
 109  */
 110 struct linux_dirent {
 111         unsigned long   d_ino;
 112         unsigned long   d_off;
 113         unsigned short  d_reclen;
 114         char            d_name[1];
 115 };
 116
 117 struct getdents_callback {
 118         struct linux_dirent * current_dir;
 119         struct linux_dirent * previous;
 120         int count;
 121         int error;
 122 };
 123
 124 static int filldir(void * __buf, const char * name, int namlen, loff_t offset,
 125                    ino_t ino, unsigned int d_type)
 126 {
 127         struct linux_dirent * dirent;
 128         struct getdents_callback * buf = (struct getdents_callback *) __buf;
 129         int reclen = ROUND_UP(NAME_OFFSET(dirent) + namlen + 1);
 130
 131         buf->error = -EINVAL;   /* only used if we fail.. */
 132         if (reclen > buf->count)
 133                 return -EINVAL;
 134         dirent = buf->previous;
 135         if (dirent)
 136                 put_user(offset, &dirent->d_off);
 137         dirent = buf->current_dir;
 138         buf->previous = dirent;
 139         put_user(ino, &dirent->d_ino);
 140         put_user(reclen, &dirent->d_reclen);
 141         copy_to_user(dirent->d_name, name, namlen);
 142         put_user(0, dirent->d_name + namlen);
 143         ((char *) dirent) += reclen;
 144         buf->current_dir = dirent;
 145         buf->count -= reclen;
 146         return 0;
 147 }
 148
 149 asmlinkage long sys_getdents(unsigned int fd, void * dirent, unsigned int count)
 150 {
 151         struct file * file;
 152         struct linux_dirent * lastdirent;
 153         struct getdents_callback buf;
 154         int error;
 155
 156         error = -EBADF;
 157         file = fget(fd);
 158         if (!file)
 159                 goto out;
 160
 161         buf.current_dir = (struct linux_dirent *) dirent;
 162         buf.previous = NULL;
 163         buf.count = count;
 164         buf.error = 0;
 165
 166         error = vfs_readdir(file, filldir, &buf);
 167         if (error < 0)
 168                 goto out_putf;
 169         error = buf.error;
 170         lastdirent = buf.previous;
 171         if (lastdirent) {
 172                 put_user(file->f_pos, &lastdirent->d_off);
 173                 error = count - buf.count;
 174         }
 175
 176 out_putf:
 177         fput(file);
 178 out:
 179         return error;
 180 }
 181
 182 /*
 183  * And even better one including d_type field and 64bit d_ino and d_off.
 184  */
 185 struct linux_dirent64 {
 186         u64             d_ino;
 187         s64             d_off;
 188         unsigned short  d_reclen;
 189         unsigned char   d_type;
 190         char            d_name[0];
 191 };
 192
 193 #define ROUND_UP64(x) (((x)+sizeof(u64)-1) & ~(sizeof(u64)-1))
 194
 195 struct getdents_callback64 {
 196         struct linux_dirent64 * current_dir;
 197         struct linux_dirent64 * previous;
 198         int count;
 199         int error;
 200 };
 201
 202 static int filldir64(void * __buf, const char * name, int namlen, loff_t offset,
 203                      ino_t ino, unsigned int d_type)
 204 {
 205         struct linux_dirent64 * dirent, d;
 206         struct getdents_callback64 * buf = (struct getdents_callback64 *) __buf;
 207         int reclen = ROUND_UP64(NAME_OFFSET(dirent) + namlen + 1);
 208
 209         buf->error = -EINVAL;   /* only used if we fail.. */
 210         if (reclen > buf->count)
 211                 return -EINVAL;
 212         dirent = buf->previous;
 213         if (dirent) {
 214                 d.d_off = offset;
 215                 copy_to_user(&dirent->d_off, &d.d_off, sizeof(d.d_off));
 216         }
 217         dirent = buf->current_dir;
 218         buf->previous = dirent;
 219         memset(&d, 0, NAME_OFFSET(&d));
 220         d.d_ino = ino;
 221         d.d_reclen = reclen;
 222         d.d_type = d_type;
 223         copy_to_user(dirent, &d, NAME_OFFSET(&d));
 224         copy_to_user(dirent->d_name, name, namlen);
 225         put_user(0, dirent->d_name + namlen);
 226         ((char *) dirent) += reclen;
 227         buf->current_dir = dirent;
 228         buf->count -= reclen;
 229         return 0;
 230 }
 231
 232 asmlinkage long sys_getdents64(unsigned int fd, void * dirent, unsigned int count)
 233 {
 234         struct file * file;
 235         struct linux_dirent64 * lastdirent;
 236         struct getdents_callback64 buf;
 237         int error;
 238
 239         error = -EBADF;
 240         file = fget(fd);
 241         if (!file)
 242                 goto out;
 243
 244         buf.current_dir = (struct linux_dirent64 *) dirent;
 245         buf.previous = NULL;
 246         buf.count = count;
 247         buf.error = 0;
 248
 249         error = vfs_readdir(file, filldir64, &buf);
 250         if (error < 0)
 251                 goto out_putf;
 252         error = buf.error;
 253         lastdirent = buf.previous;
 254         if (lastdirent) {
 255                 struct linux_dirent64 d;
 256                 d.d_off = file->f_pos;
 257                 copy_to_user(&lastdirent->d_off, &d.d_off, sizeof(d.d_off));
 258                 error = count - buf.count;
 259         }
 260
 261 out_putf:
 262         fput(file);
 263 out:
 264         return error;
 265 }