fs/ufs/symlink.c

   1 /*
   2  *  linux/ufs/ufs/symlink.c
   3  *
   4  * Copyright (C) 1998
   5  * Daniel Pirkl <daniel.pirkl@emai.cz>
   6  * Charles University, Faculty of Mathematics and Physics
   7  *
   8  *  from
   9  *
  10  *  linux/fs/ext2/symlink.c
  11  *
  12  * Copyright (C) 1992, 1993, 1994, 1995
  13  * Remy Card (card@masi.ibp.fr)
  14  * Laboratoire MASI - Institut Blaise Pascal
  15  * Universite Pierre et Marie Curie (Paris VI)
  16  *
  17  *  from
  18  *
  19  *  linux/fs/minix/symlink.c
  20  *
  21  *  Copyright (C) 1991, 1992  Linus Torvalds
  22  *
  23  *  ext2 symlink handling code
  24  */
  25
  26 #include <asm/uaccess.h>
  27
  28 #include <linux/errno.h>
  29 #include <linux/fs.h>
  30 #include <linux/ext2_fs.h>
  31 #include <linux/sched.h>
  32 #include <linux/mm.h>
  33 #include <linux/stat.h>
  34
  35
  36 #undef UFS_SYMLINK_DEBUG
  37
  38 #ifdef UFS_SYMLINK_DEBUG
  39 #define UFSD(x) printk("(%s, %d), %s:", __FILE__, __LINE__, __FUNCTION__); printk x;
  40 #else
  41 #define UFSD(x)
  42 #endif
  43
  44
  45 static struct dentry * ufs_follow_link(struct dentry * dentry,
  46         struct dentry * base)
  47 {
  48         struct inode * inode;
  49         struct buffer_head * bh;
  50         int error;
  51         char * link;
  52
  53         UFSD(("ENTER\n"))
  54
  55         inode = dentry->d_inode;
  56         bh = NULL;
  57         /* slow symlink */
  58         if (inode->i_blocks) {
  59                 if (!(bh = ufs_bread (inode, 0, 0, &error))) {
  60                         dput(base);
  61                         return ERR_PTR(-EIO);
  62                 }
  63                 link = bh->b_data;
  64         }
  65         /* fast symlink */
  66         else {
  67                 link = (char *) inode->u.ufs_i.i_u1.i_symlink;
  68         }
  69         UPDATE_ATIME(inode);
  70         base = lookup_dentry(link, base, 1);
  71         if (bh)
  72                 brelse(bh);
  73         UFSD(("EXIT\n"))
  74         return base;
  75 }
  76
  77 static int ufs_readlink (struct dentry * dentry, char * buffer, int buflen)
  78 {
  79         struct super_block * sb;
  80         struct inode * inode;
  81         struct buffer_head * bh;
  82         char * link;
  83         int i;
  84
  85         UFSD(("ENTER\n"))
  86
  87         inode = dentry->d_inode;
  88         sb = inode->i_sb;
  89         bh = NULL;
  90         if (buflen > sb->s_blocksize - 1)
  91                 buflen = sb->s_blocksize - 1;
  92         /* slow symlink */
  93         if (inode->i_blocks) {
  94                 int err;
  95                 bh = ufs_bread (inode, 0, 0, &err);
  96                 if (!bh) {
  97                         if(err < 0) /* indicate type of error */
  98                                 return err;
  99                         return 0;
 100                 }
 101                 link = bh->b_data;
 102         }
 103         /* fast symlink */
 104         else {
 105                 link = (char *) inode->u.ufs_i.i_u1.i_symlink;
 106         }
 107         i = 0;
 108         while (i < buflen && link[i])
 109                 i++;
 110         if (copy_to_user(buffer, link, i))
 111                 i = -EFAULT;
 112         UPDATE_ATIME(inode);
 113         if (bh)
 114                 brelse (bh);
 115         UFSD(("ENTER\n"))
 116         return i;
 117 }
 118
 119 struct inode_operations ufs_symlink_inode_operations = {
 120         NULL,                   /* no file-operations */
 121         NULL,                   /* create */
 122         NULL,                   /* lookup */
 123         NULL,                   /* link */
 124         NULL,                   /* unlink */
 125         NULL,                   /* symlink */
 126         NULL,                   /* mkdir */
 127         NULL,                   /* rmdir */
 128         NULL,                   /* mknod */
 129         NULL,                   /* rename */
 130         ufs_readlink,           /* readlink */
 131         ufs_follow_link,        /* follow_link */
 132         NULL,                   /* readpage */
 133         NULL,                   /* writepage */
 134         NULL,                   /* bmap */
 135         NULL,                   /* truncate */
 136         NULL,                   /* permission */
 137         NULL                    /* smap */
 138 };