EFS integration (read-only, slight problem with symlinks).

1 files changed, 136 insertions, 0 deletions

diff --git a/fs/efs/symlink.c b/fs/efs/symlink.c
new file mode 100644
index 000000000..6197bb6f3
--- /dev/null
+++ b/fs/efs/symlink.c
@@ -0,0 +1,136 @@
+/* symlink.c
+ *
+ * Symbolic link handling for EFS
+ *
+ * (C)1995,96 Christian Vogelgsang
+ *
+ * Based on the symlink.c from minix-fs by Linus
+ */
+
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/fs.h>
+#include <linux/efs_fs.h>
+#include <linux/stat.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <asm/uaccess.h>
+
+static int efs_readlink(struct inode *, char *, int);
+static struct dentry * efs_follow_link(struct inode *, struct dentry *);
+
+struct inode_operations efs_symlink_in_ops = {
+	NULL,			/* no file-operations */
+	NULL,			/* create */
+	NULL,			/* lookup */
+	NULL,			/* link */
+	NULL,			/* unlink */
+	NULL,			/* symlink */
+	NULL,			/* mkdir */
+	NULL,			/* rmdir */
+	NULL,			/* mknod */
+	NULL,			/* rename */
+	efs_readlink,		/* readlink */
+	efs_follow_link,	/* follow_link */
+	NULL,
+	NULL,
+	NULL,			/* bmap */
+	NULL,			/* truncate */
+	NULL			/* permission */
+};
+
+
+/* ----- efs_getlinktarget -----
+   read the target of the link from the data zone of the file
+*/
+static char *efs_getlinktarget(struct inode *in)
+{
+  struct buffer_head * bh;
+  char *name;
+  __u32 size = in->i_size;
+  __u32 block;
+  
+  /* link data longer than 1024 not supported */
+  if(size>2*EFS_BLOCK_SIZE) {
+    printk("efs_getlinktarget: name too long: %lu\n",in->i_size);
+    return NULL;
+  }
+  
+  /* get some memory from the kernel to store the name */
+  name = kmalloc(size+1,GFP_KERNEL);
+  if(!name) return NULL;
+  
+  /* read first 512 bytes of target */
+  block = efs_bmap(in,0);
+  bh = bread(in->i_dev,block,EFS_BLOCK_SIZE);
+  if(!bh) {
+    kfree(name);
+    return NULL;
+  }
+  memcpy(name,bh->b_data,(size>EFS_BLOCK_SIZE)?EFS_BLOCK_SIZE:size);
+  brelse(bh);
+  
+  /* if the linktarget is long, read the next block */
+  if(size>EFS_BLOCK_SIZE) {
+    bh = bread(in->i_dev,block+1,EFS_BLOCK_SIZE);
+    if(!bh) {
+      kfree(name);
+      return NULL;
+    }
+    memcpy(name+EFS_BLOCK_SIZE,bh->b_data,size-EFS_BLOCK_SIZE);
+    brelse(bh);
+  }
+  
+  /* terminate string and return it */
+  name[size]=0;
+  return name;
+}
+
+
+/* ----- efs_follow_link -----
+   get the inode of the link target
+*/
+static struct dentry * efs_follow_link(struct inode * dir, struct dentry *base)
+{
+  struct buffer_head * bh;
+  __u32 block;
+
+  block = efs_bmap(dir,0);
+  bh = bread(dir->i_dev,block,EFS_BLOCK_SIZE);
+  if (!bh) {
+    dput(base);
+    return ERR_PTR(-EIO);
+  }
+  UPDATE_ATIME(dir);
+  base = lookup_dentry(bh->b_data, base, 1);
+  brelse(bh);
+  return base;
+}
+
+/* ----- efs_readlink -----
+   read the target of a link and return the name
+*/
+static int efs_readlink(struct inode * dir, char * buffer, int buflen)
+{
+  int i;
+  char c;
+  struct buffer_head * bh;
+  __u32 block;
+
+  block = efs_bmap(dir,0);
+  if (buflen > 1023)
+    buflen = 1023;
+  bh = bread(dir->i_dev,block,EFS_BLOCK_SIZE);
+  if (!bh)
+    return 0;
+
+  /* copy the link target to the given buffer */
+  i = 0;
+  while (i<buflen && (c = bh->b_data[i])) {
+    i++;
+    put_user(c,buffer++);
+  }
+
+  brelse(bh);
+  return i;
+}