Invent path-based inode numbers

* procfs.h, procfs.c (procfs_make_ino): New function,
  invents an inode number by hashing the parent's and the name of an
  entry.  (procfs_lookup): Use it to assign an inode number to child
  nodes at lookup time.
* main.c (root_make_node): Assign an arbitrary inode number to
  the root directory.

3 files changed, 36 insertions, 1 deletions

diff --git a/main.c b/main.c
index e08bbdb7..15602819 100644
--- a/main.c
+++ b/main.c
@@ -42,6 +42,10 @@ root_make_node (struct node **np)
   if (! *np)
     return ENOMEM;
 
+  /* Since this one is not created through proc_lookup(), we have to affect an
+     inode number to it.  */
+  (*np)->nn_stat.st_ino = * (uint32_t *) "PROC";
+
   return 0;
 }
 
diff --git a/procfs.c b/procfs.c
index c5f19497..4cce46b9 100644
--- a/procfs.c
+++ b/procfs.c
@@ -67,6 +67,29 @@ fail:
   return NULL;
 }
 
+/* FIXME: possibly not the fastest hash function... */
+ino64_t
+procfs_make_ino (struct node *np, const char *filename)
+{
+  unsigned short x[3];
+
+  if (! strcmp (filename, "."))
+    return np->nn_stat.st_ino;
+  if (! strcmp (filename, ".."))
+    return np->nn->parent ? np->nn->parent->nn_stat.st_ino : /* FIXME: */ 42;
+
+  assert (sizeof np->nn_stat.st_ino > sizeof x);
+  memcpy (x, &np->nn_stat.st_ino, sizeof x);
+
+  while (*filename)
+    {
+      x[0] ^= *(filename++);
+      jrand48 (x);
+    }
+
+  return jrand48 (x);
+}
+
 error_t procfs_get_contents (struct node *np, void **data, size_t *data_len)
 {
   if (np->nn->ops->enable_refresh_hack_and_break_readdir && np->nn->contents)
@@ -116,7 +139,10 @@ error_t procfs_lookup (struct node *np, const char *name, struct node **npp)
     {
       err = np->nn->ops->lookup (np->nn->hook, name, npp);
       if (! err)
-	netfs_nref ((*npp)->nn->parent = np);
+        {
+	  (*npp)->nn_stat.st_ino = procfs_make_ino (np, name);
+	  netfs_nref ((*npp)->nn->parent = np);
+	}
     }
 
   return err;
diff --git a/procfs.h b/procfs.h
index 42eed0e2..4c9d828b 100644
--- a/procfs.h
+++ b/procfs.h
@@ -51,6 +51,11 @@ struct node *procfs_make_node (const struct procfs_node_ops *ops, void *hook);
 
 /* Interface for the libnetfs side. */
 
+/* Get the inode number which will be given to a child of NP named FILENAME.
+   This allows us to retreive them for readdir() without creating the
+   corresponding child nodes.  */
+ino64_t procfs_make_ino (struct node *np, const char *filename);
+
 error_t procfs_get_contents (struct node *np, void **data, size_t *data_len);
 error_t procfs_lookup (struct node *np, const char *name, struct node **npp);
 void procfs_cleanup (struct node *np);