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 #ifndef __ia64__
  94
  95 struct old_linux_dirent {
  96         unsigned long   d_ino;
  97         unsigned long   d_offset;
  98         unsigned short  d_namlen;
  99         char            d_name[1];
 100 };
 101
 102 struct readdir_callback {
 103         struct old_linux_dirent * dirent;
 104         int count;
 105 };
 106
 107 static int fillonedir(void * __buf, const char * name, int namlen, off_t offset, ino_t ino)
 108 {
 109         struct readdir_callback * buf = (struct readdir_callback *) __buf;
 110         struct old_linux_dirent * dirent;
 111
 112         if (buf->count)
 113                 return -EINVAL;
 114         buf->count++;
 115         dirent = buf->dirent;
 116         put_user(ino, &dirent->d_ino);
 117         put_user(offset, &dirent->d_offset);
 118         put_user(namlen, &dirent->d_namlen);
 119         copy_to_user(dirent->d_name, name, namlen);
 120         put_user(0, dirent->d_name + namlen);
 121         return 0;
 122 }
 123
 124 asmlinkage int old_readdir(unsigned int fd, void * dirent, unsigned int count)
 125 {
 126         int error;
 127         struct file * file;
 128         struct readdir_callback buf;
 129
 130         error = -EBADF;
 131         file = fget(fd);
 132         if (!file)
 133                 goto out;
 134
 135         buf.count = 0;
 136         buf.dirent = dirent;
 137
 138         lock_kernel();
 139         error = vfs_readdir(file, fillonedir, &buf);
 140         if (error >= 0)
 141                 error = buf.count;
 142         unlock_kernel();
 143
 144         fput(file);
 145 out:
 146         return error;
 147 }
 148
 149 #endif /* !__ia64__ */
 150
 151 /*
 152  * New, all-improved, singing, dancing, iBCS2-compliant getdents()
 153  * interface.
 154  */
 155 struct linux_dirent {
 156         unsigned long   d_ino;
 157         unsigned long   d_off;
 158         unsigned short  d_reclen;
 159         char            d_name[1];
 160 };
 161
 162 struct getdents_callback {
 163         struct linux_dirent * current_dir;
 164         struct linux_dirent * previous;
 165         int count;
 166         int error;
 167 };
 168
 169 static int filldir(void * __buf, const char * name, int namlen, off_t offset, ino_t ino)
 170 {
 171         struct linux_dirent * dirent;
 172         struct getdents_callback * buf = (struct getdents_callback *) __buf;
 173         int reclen = ROUND_UP(NAME_OFFSET(dirent) + namlen + 1);
 174
 175         buf->error = -EINVAL;   /* only used if we fail.. */
 176         if (reclen > buf->count)
 177                 return -EINVAL;
 178         dirent = buf->previous;
 179         if (dirent)
 180                 put_user(offset, &dirent->d_off);
 181         dirent = buf->current_dir;
 182         buf->previous = dirent;
 183         put_user(ino, &dirent->d_ino);
 184         put_user(reclen, &dirent->d_reclen);
 185         copy_to_user(dirent->d_name, name, namlen);
 186         put_user(0, dirent->d_name + namlen);
 187         ((char *) dirent) += reclen;
 188         buf->current_dir = dirent;
 189         buf->count -= reclen;
 190         return 0;
 191 }
 192
 193 asmlinkage long sys_getdents(unsigned int fd, void * dirent, unsigned int count)
 194 {
 195         struct file * file;
 196         struct linux_dirent * lastdirent;
 197         struct getdents_callback buf;
 198         int error;
 199
 200         error = -EBADF;
 201         file = fget(fd);
 202         if (!file)
 203                 goto out;
 204
 205         buf.current_dir = (struct linux_dirent *) dirent;
 206         buf.previous = NULL;
 207         buf.count = count;
 208         buf.error = 0;
 209
 210         lock_kernel();
 211         error = vfs_readdir(file, filldir, &buf);
 212         if (error < 0)
 213                 goto out_putf;
 214         error = buf.error;
 215         lastdirent = buf.previous;
 216         if (lastdirent) {
 217                 put_user(file->f_pos, &lastdirent->d_off);
 218                 error = count - buf.count;
 219         }
 220
 221 out_putf:
 222         unlock_kernel();
 223         fput(file);
 224 out:
 225         return error;
 226 }