fs/readdir.c

   1 /*
   2  *  linux/fs/readdir.c
   3  *
   4  *  Copyright (C) 1995  Linus Torvalds
   5  */
   6
   7 #include <linux/sched.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
  14 #include <asm/uaccess.h>
  15
  16 int vfs_readdir(struct file *file, filldir_t filler, void *buf)
  17 {
  18         struct inode *inode = file->f_dentry->d_inode;
  19         int res = -ENOTDIR;
  20         if (!file->f_op || !file->f_op->readdir)
  21                 goto out;
  22         down(&inode->i_sem);
  23         down(&inode->i_zombie);
  24         res = -ENOENT;
  25         if (!IS_DEADDIR(inode)) {
  26                 lock_kernel();
  27                 res = file->f_op->readdir(file, buf, filler);
  28                 unlock_kernel();
  29         }
  30         up(&inode->i_zombie);
  31         up(&inode->i_sem);
  32 out:
  33         return res;
  34 }
  35
  36 /*
  37  * Directory is locked and all positive dentries in it are safe, since
  38  * for ramfs-type trees they can't go away without unlink() or rmdir(),
  39  * both impossible due to the lock on directory.
  40  */
  41
  42 int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)
  43 {
  44         int i;
  45         struct dentry *dentry = filp->f_dentry;
  46
  47         i = filp->f_pos;
  48         switch (i) {
  49                 case 0:
  50                         if (filldir(dirent, ".", 1, i, dentry->d_inode->i_ino, DT_DIR) < 0)
  51                                 break;
  52                         i++;
  53                         filp->f_pos++;
  54                         /* fallthrough */
  55                 case 1:
  56                         if (filldir(dirent, "..", 2, i, dentry->d_parent->d_inode->i_ino, DT_DIR) < 0)
  57                                 break;
  58                         i++;
  59                         filp->f_pos++;
  60                         /* fallthrough */
  61                 default: {
  62                         struct list_head *list;
  63                         int j = i-2;
  64
  65                         spin_lock(&dcache_lock);
  66                         list = dentry->d_subdirs.next;
  67
  68                         for (;;) {
  69                                 if (list == &dentry->d_subdirs) {
  70                                         spin_unlock(&dcache_lock);
  71                                         return 0;
  72                                 }
  73                                 if (!j)
  74                                         break;
  75                                 j--;
  76                                 list = list->next;
  77                         }
  78
  79                         while(1) {
  80                                 struct dentry *de = list_entry(list, struct dentry, d_child);
  81
  82                                 if (!list_empty(&de->d_hash) && de->d_inode) {
  83                                         spin_unlock(&dcache_lock);
  84                                         if (filldir(dirent, de->d_name.name, de->d_name.len, filp->f_pos, de->d_inode->i_ino, DT_UNKNOWN) < 0)
  85                                                 break;
  86                                         spin_lock(&dcache_lock);
  87                                 }
  88                                 filp->f_pos++;
  89                                 list = list->next;
  90                                 if (list != &dentry->d_subdirs)
  91                                         continue;
  92                                 spin_unlock(&dcache_lock);
  93                                 break;
  94                         }
  95                 }
  96         }
  97         return 0;
  98 }
  99
 100 /*
 101  * Traditional linux readdir() handling..
 102  *
 103  * "count=1" is a special case, meaning that the buffer is one
 104  * dirent-structure in size and that the code can't handle more
 105  * anyway. Thus the special "fillonedir()" function for that
 106  * case (the low-level handlers don't need to care about this).
 107  */
 108 #define NAME_OFFSET(de) ((int) ((de)->d_name - (char *) (de)))
 109 #define ROUND_UP(x) (((x)+sizeof(long)-1) & ~(sizeof(long)-1))
 110
 111 #ifndef __ia64__
 112
 113 struct old_linux_dirent {
 114         unsigned long   d_ino;
 115         unsigned long   d_offset;
 116         unsigned short  d_namlen;
 117         char            d_name[1];
 118 };
 119
 120 struct readdir_callback {
 121         struct old_linux_dirent * dirent;
 122         int count;
 123 };
 124
 125 static int fillonedir(void * __buf, const char * name, int namlen, off_t offset,
 126                       ino_t ino, unsigned int d_type)
 127 {
 128         struct readdir_callback * buf = (struct readdir_callback *) __buf;
 129         struct old_linux_dirent * dirent;
 130
 131         if (buf->count)
 132                 return -EINVAL;
 133         buf->count++;
 134         dirent = buf->dirent;
 135         put_user(ino, &dirent->d_ino);
 136         put_user(offset, &dirent->d_offset);
 137         put_user(namlen, &dirent->d_namlen);
 138         copy_to_user(dirent->d_name, name, namlen);
 139         put_user(0, dirent->d_name + namlen);
 140         return 0;
 141 }
 142
 143 asmlinkage int old_readdir(unsigned int fd, void * dirent, unsigned int count)
 144 {
 145         int error;
 146         struct file * file;
 147         struct readdir_callback buf;
 148
 149         error = -EBADF;
 150         file = fget(fd);
 151         if (!file)
 152                 goto out;
 153
 154         buf.count = 0;
 155         buf.dirent = dirent;
 156
 157         error = vfs_readdir(file, fillonedir, &buf);
 158         if (error >= 0)
 159                 error = buf.count;
 160
 161         fput(file);
 162 out:
 163         return error;
 164 }
 165
 166 #endif /* !__ia64__ */
 167
 168 /*
 169  * New, all-improved, singing, dancing, iBCS2-compliant getdents()
 170  * interface.
 171  */
 172 struct linux_dirent {
 173         unsigned long   d_ino;
 174         unsigned long   d_off;
 175         unsigned short  d_reclen;
 176         char            d_name[1];
 177 };
 178
 179 struct getdents_callback {
 180         struct linux_dirent * current_dir;
 181         struct linux_dirent * previous;
 182         int count;
 183         int error;
 184 };
 185
 186 static int filldir(void * __buf, const char * name, int namlen, off_t offset,
 187                    ino_t ino, unsigned int d_type)
 188 {
 189         struct linux_dirent * dirent;
 190         struct getdents_callback * buf = (struct getdents_callback *) __buf;
 191         int reclen = ROUND_UP(NAME_OFFSET(dirent) + namlen + 1);
 192
 193         buf->error = -EINVAL;   /* only used if we fail.. */
 194         if (reclen > buf->count)
 195                 return -EINVAL;
 196         dirent = buf->previous;
 197         if (dirent)
 198                 put_user(offset, &dirent->d_off);
 199         dirent = buf->current_dir;
 200         buf->previous = dirent;
 201         put_user(ino, &dirent->d_ino);
 202         put_user(reclen, &dirent->d_reclen);
 203         copy_to_user(dirent->d_name, name, namlen);
 204         put_user(0, dirent->d_name + namlen);
 205         ((char *) dirent) += reclen;
 206         buf->current_dir = dirent;
 207         buf->count -= reclen;
 208         return 0;
 209 }
 210
 211 asmlinkage long sys_getdents(unsigned int fd, void * dirent, unsigned int count)
 212 {
 213         struct file * file;
 214         struct linux_dirent * lastdirent;
 215         struct getdents_callback buf;
 216         int error;
 217
 218         error = -EBADF;
 219         file = fget(fd);
 220         if (!file)
 221                 goto out;
 222
 223         buf.current_dir = (struct linux_dirent *) dirent;
 224         buf.previous = NULL;
 225         buf.count = count;
 226         buf.error = 0;
 227
 228         error = vfs_readdir(file, filldir, &buf);
 229         if (error < 0)
 230                 goto out_putf;
 231         error = buf.error;
 232         lastdirent = buf.previous;
 233         if (lastdirent) {
 234                 put_user(file->f_pos, &lastdirent->d_off);
 235                 error = count - buf.count;
 236         }
 237
 238 out_putf:
 239         fput(file);
 240 out:
 241         return error;
 242 }
 243
 244 /*
 245  * And even better one including d_type field and 64bit d_ino and d_off.
 246  */
 247 struct linux_dirent64 {
 248         u64             d_ino;
 249         s64             d_off;
 250         unsigned short  d_reclen;
 251         unsigned char   d_type;
 252         char            d_name[0];
 253 };
 254
 255 #define ROUND_UP64(x) (((x)+sizeof(u64)-1) & ~(sizeof(u64)-1))
 256
 257 struct getdents_callback64 {
 258         struct linux_dirent64 * current_dir;
 259         struct linux_dirent64 * previous;
 260         int count;
 261         int error;
 262 };
 263
 264 static int filldir64(void * __buf, const char * name, int namlen, off_t offset,
 265                      ino_t ino, unsigned int d_type)
 266 {
 267         struct linux_dirent64 * dirent, d;
 268         struct getdents_callback64 * buf = (struct getdents_callback64 *) __buf;
 269         int reclen = ROUND_UP64(NAME_OFFSET(dirent) + namlen + 1);
 270
 271         buf->error = -EINVAL;   /* only used if we fail.. */
 272         if (reclen > buf->count)
 273                 return -EINVAL;
 274         dirent = buf->previous;
 275         if (dirent) {
 276                 d.d_off = offset;
 277                 copy_to_user(&dirent->d_off, &d.d_off, sizeof(d.d_off));
 278         }
 279         dirent = buf->current_dir;
 280         buf->previous = dirent;
 281         memset(&d, 0, NAME_OFFSET(&d));
 282         d.d_ino = ino;
 283         d.d_reclen = reclen;
 284         d.d_type = d_type;
 285         copy_to_user(dirent, &d, NAME_OFFSET(&d));
 286         copy_to_user(dirent->d_name, name, namlen);
 287         put_user(0, dirent->d_name + namlen);
 288         ((char *) dirent) += reclen;
 289         buf->current_dir = dirent;
 290         buf->count -= reclen;
 291         return 0;
 292 }
 293
 294 asmlinkage long sys_getdents64(unsigned int fd, void * dirent, unsigned int count)
 295 {
 296         struct file * file;
 297         struct linux_dirent64 * lastdirent;
 298         struct getdents_callback64 buf;
 299         int error;
 300
 301         error = -EBADF;
 302         file = fget(fd);
 303         if (!file)
 304                 goto out;
 305
 306         buf.current_dir = (struct linux_dirent64 *) dirent;
 307         buf.previous = NULL;
 308         buf.count = count;
 309         buf.error = 0;
 310
 311         error = vfs_readdir(file, filldir64, &buf);
 312         if (error < 0)
 313                 goto out_putf;
 314         error = buf.error;
 315         lastdirent = buf.previous;
 316         if (lastdirent) {
 317                 struct linux_dirent64 d;
 318                 d.d_off = file->f_pos;
 319                 copy_to_user(&lastdirent->d_off, &d.d_off, sizeof(d.d_off));
 320                 error = count - buf.count;
 321         }
 322
 323 out_putf:
 324         fput(file);
 325 out:
 326         return error;
 327 }