fs/ext2/symlink.c

/* */
This source file includes following definitions.
ext2_follow_link
ext2_readlink
   1 /*
   2  *  linux/fs/ext2/symlink.c
   3  *
   4  * Copyright (C) 1992, 1993, 1994, 1995
   5  * Remy Card (card@masi.ibp.fr)
   6  * Laboratoire MASI - Institut Blaise Pascal
   7  * Universite Pierre et Marie Curie (Paris VI)
   8  *
   9  *  from
  10  *
  11  *  linux/fs/minix/symlink.c
  12  *
  13  *  Copyright (C) 1991, 1992  Linus Torvalds
  14  *
  15  *  ext2 symlink handling code
  16  */
  17 
  18 #include <asm/segment.h>
  19 
  20 #include <linux/errno.h>
  21 #include <linux/fs.h>
  22 #include <linux/ext2_fs.h>
  23 #include <linux/sched.h>
  24 #include <linux/stat.h>
  25 
  26 static int ext2_readlink (struct inode *, char *, int);
  27 static int ext2_follow_link (struct inode *, struct inode *, int, int,
  28                                struct inode **);
  29 
  30 /*
  31  * symlinks can't do much...
  32  */
  33 struct inode_operations ext2_symlink_inode_operations = {
  34         NULL,                   /* no file-operations */
  35         NULL,                   /* create */
  36         NULL,                   /* lookup */
  37         NULL,                   /* link */
  38         NULL,                   /* unlink */
  39         NULL,                   /* symlink */
  40         NULL,                   /* mkdir */
  41         NULL,                   /* rmdir */
  42         NULL,                   /* mknod */
  43         NULL,                   /* rename */
  44         ext2_readlink,          /* readlink */
  45         ext2_follow_link,       /* follow_link */
  46         NULL,                   /* readpage */
  47         NULL,                   /* writepage */
  48         NULL,                   /* bmap */
  49         NULL,                   /* truncate */
  50         NULL,                   /* permission */
  51         NULL                    /* smap */
  52 };
  53 
  54 static int ext2_follow_link(struct inode * dir, struct inode * inode,
     /*  */
  55                             int flag, int mode, struct inode ** res_inode)
  56 {
  57         int error;
  58         struct buffer_head * bh = NULL;
  59         char * link;
  60 
  61         *res_inode = NULL;
  62         if (!dir) {
  63                 dir = current->fs->root;
  64                 dir->i_count++;
  65         }
  66         if (!inode) {
  67                 iput (dir);
  68                 return -ENOENT;
  69         }
  70         if (!S_ISLNK(inode->i_mode)) {
  71                 iput (dir);
  72                 *res_inode = inode;
  73                 return 0;
  74         }
  75         if (current->link_count > 5) {
  76                 iput (dir);
  77                 iput (inode);
  78                 return -ELOOP;
  79         }
  80         if (inode->i_blocks) {
  81                 if (!(bh = ext2_bread (inode, 0, 0, &error))) {
  82                         iput (dir);
  83                         iput (inode);
  84                         return -EIO;
  85                 }
  86                 link = bh->b_data;
  87         } else
  88                 link = (char *) inode->u.ext2_i.i_data;
  89         current->link_count++;
  90         error = open_namei (link, flag, mode, res_inode, dir);
  91         current->link_count--;
  92         iput (inode);
  93         if (bh)
  94                 brelse (bh);
  95         return error;
  96 }
  97 
  98 static int ext2_readlink (struct inode * inode, char * buffer, int buflen)
     /*  */
  99 {
 100         struct buffer_head * bh = NULL;
 101         char * link;
 102         int i, err;
 103         char c;
 104 
 105         if (!S_ISLNK(inode->i_mode)) {
 106                 iput (inode);
 107                 return -EINVAL;
 108         }
 109         if (buflen > inode->i_sb->s_blocksize - 1)
 110                 buflen = inode->i_sb->s_blocksize - 1;
 111         if (inode->i_blocks) {
 112                 bh = ext2_bread (inode, 0, 0, &err);
 113                 if (!bh) {
 114                         iput (inode);
 115                         return 0;
 116                 }
 117                 link = bh->b_data;
 118         }
 119         else
 120                 link = (char *) inode->u.ext2_i.i_data;
 121         i = 0;
 122         while (i < buflen && (c = link[i])) {
 123                 i++;
 124                 put_user (c, buffer++);
 125         }
 126         iput (inode);
 127         if (bh)
 128                 brelse (bh);
 129         return i;
 130 }
/* */
root/fs/ext2/symlink.c

DEFINITIONS
