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,
  17                 int (*filler)(void *,const char *,int,off_t,ino_t),
  18                 void *buf)
  19 {
  20         struct inode *inode = file->f_dentry->d_inode;
  21         int res = -ENOTDIR;
  22         if (!file->f_op || !file->f_op->readdir)
  23                 goto out;
  24         down(&inode->i_sem);
  25         down(&inode->i_zombie);
  26         res = -ENOENT;
  27         if (!IS_DEADDIR(inode))
  28                 res = file->f_op->readdir(file, buf, filler);
  29         up(&inode->i_zombie);
  30         up(&inode->i_sem);
  31 out:
  32         return res;
  33 }
  34
  35 int dcache_readdir(struct file * filp, void * dirent, filldir_t filldir)
  36 {
  37         int i;
  38         struct dentry *dentry = filp->f_dentry;
  39
  40         i = filp->f_pos;
  41         switch (i) {
  42                 case 0:
  43                         if (filldir(dirent, ".", 1, i, dentry->d_inode->i_ino) < 0)
  44                                 break;
  45                         i++;
  46                         filp->f_pos++;
  47                         /* fallthrough */
  48                 case 1:
  49                         if (filldir(dirent, "..", 2, i, dentry->d_parent->d_inode->i_ino) < 0)
  50                                 break;
  51                         i++;
  52                         filp->f_pos++;
  53                         /* fallthrough */
  54                 default: {
  55                         struct list_head *list = dentry->d_subdirs.next;
  56
  57                         int j = i-2;
  58                         for (;;) {
  59                                 if (list == &dentry->d_subdirs)
  60                                         return 0;
  61                                 if (!j)
  62                                         break;
  63                                 j--;
  64                                 list = list->next;
  65                         }
  66
  67                         do {
  68                                 struct dentry *de = list_entry(list, struct dentry, d_child);
  69
  70                                 if (!d_unhashed(de) && de->d_inode) {
  71                                         if (filldir(dirent, de->d_name.name, de->d_name.len, filp->f_pos, de->d_inode->i_ino) < 0)
  72                                                 break;
  73                                 }
  74                                 filp->f_pos++;
  75                                 list = list->next;
  76                         } while (list != &dentry->d_subdirs);
  77                 }
  78         }
  79         return 0;
  80 }
  81
  82 /*
  83  * Traditional linux readdir() handling..
  84  *
  85  * "count=1" is a special case, meaning that the buffer is one
  86  * dirent-structure in size and that the code can't handle more
  87  * anyway. Thus the special "fillonedir()" function for that
  88  * case (the low-level handlers don't need to care about this).
  89  */
  90 #define NAME_OFFSET(de) ((int) ((de)->d_name - (char *) (de)))
  91 #define ROUND_UP(x) (((x)+sizeof(long)-1) & ~(sizeof(long)-1))
  92
  93 struct old_linux_dirent {
  94         unsigned long   d_ino;
  95         unsigned long   d_offset;
  96         unsigned short  d_namlen;
  97         char            d_name[1];
  98 };
  99
 100 struct readdir_callback {
 101         struct old_linux_dirent * dirent;
 102         int count;
 103 };
 104
 105 static int fillonedir(void * __buf, const char * name, int namlen, off_t offset, ino_t ino)
 106 {
 107         struct readdir_callback * buf = (struct readdir_callback *) __buf;
 108         struct old_linux_dirent * dirent;
 109
 110         if (buf->count)
 111                 return -EINVAL;
 112         buf->count++;
 113         dirent = buf->dirent;
 114         put_user(ino, &dirent->d_ino);
 115         put_user(offset, &dirent->d_offset);
 116         put_user(namlen, &dirent->d_namlen);
 117         copy_to_user(dirent->d_name, name, namlen);
 118         put_user(0, dirent->d_name + namlen);
 119         return 0;
 120 }
 121
 122 asmlinkage int old_readdir(unsigned int fd, void * dirent, unsigned int count)
 123 {
 124         int error;
 125         struct file * file;
 126         struct readdir_callback buf;
 127
 128         error = -EBADF;
 129         file = fget(fd);
 130         if (!file)
 131                 goto out;
 132
 133         buf.count = 0;
 134         buf.dirent = dirent;
 135
 136         lock_kernel();
 137         error = vfs_readdir(file, fillonedir, &buf);
 138         if (error >= 0)
 139                 error = buf.count;
 140         unlock_kernel();
 141
 142         fput(file);
 143 out:
 144         return error;
 145 }
 146
 147 /*
 148  * New, all-improved, singing, dancing, iBCS2-compliant getdents()
 149  * interface.
 150  */
 151 struct linux_dirent {
 152         unsigned long   d_ino;
 153         unsigned long   d_off;
 154         unsigned short  d_reclen;
 155         char            d_name[1];
 156 };
 157
 158 struct getdents_callback {
 159         struct linux_dirent * current_dir;
 160         struct linux_dirent * previous;
 161         int count;
 162         int error;
 163 };
 164
 165 static int filldir(void * __buf, const char * name, int namlen, off_t offset, ino_t ino)
 166 {
 167         struct linux_dirent * dirent;
 168         struct getdents_callback * buf = (struct getdents_callback *) __buf;
 169         int reclen = ROUND_UP(NAME_OFFSET(dirent) + namlen + 1);
 170
 171         buf->error = -EINVAL;   /* only used if we fail.. */
 172         if (reclen > buf->count)
 173                 return -EINVAL;
 174         dirent = buf->previous;
 175         if (dirent)
 176                 put_user(offset, &dirent->d_off);
 177         dirent = buf->current_dir;
 178         buf->previous = dirent;
 179         put_user(ino, &dirent->d_ino);
 180         put_user(reclen, &dirent->d_reclen);
 181         copy_to_user(dirent->d_name, name, namlen);
 182         put_user(0, dirent->d_name + namlen);
 183         ((char *) dirent) += reclen;
 184         buf->current_dir = dirent;
 185         buf->count -= reclen;
 186         return 0;
 187 }
 188
 189 asmlinkage long sys_getdents(unsigned int fd, void * dirent, unsigned int count)
 190 {
 191         struct file * file;
 192         struct linux_dirent * lastdirent;
 193         struct getdents_callback buf;
 194         int error;
 195
 196         error = -EBADF;
 197         file = fget(fd);
 198         if (!file)
 199                 goto out;
 200
 201         buf.current_dir = (struct linux_dirent *) dirent;
 202         buf.previous = NULL;
 203         buf.count = count;
 204         buf.error = 0;
 205
 206         lock_kernel();
 207         error = vfs_readdir(file, filldir, &buf);
 208         if (error < 0)
 209                 goto out_putf;
 210         error = buf.error;
 211         lastdirent = buf.previous;
 212         if (lastdirent) {
 213                 put_user(file->f_pos, &lastdirent->d_off);
 214                 error = count - buf.count;
 215         }
 216
 217 out_putf:
 218         unlock_kernel();
 219         fput(file);
 220 out:
 221         return error;
 222 }