Create SFFS library out of HGFS

This Shared Folders File System library (libsffs) now contains all the
file system logic originally in HGFS. The actual HGFS server code is
now a stub that passes on all the work to libsffs. The libhgfs library
is changed accordingly.

lib/libsffs/verify.c

@@ -0,0 +1,119 @@
+/* This file contains routines that verify inodes and paths against the host.
+ *
+ * The entry points into this file are:
+ *   verify_path	check whether a path,inode pair is still valid
+ *   verify_inode	construct a path for an inode and verify the inode
+ *   verify_dentry	check a directory inode and look for a directory entry
+ *
+ * Created:
+ *   April 2009 (D.C. van Moolenbroek)
+ */
+
+#include "inc.h"
+
+/*===========================================================================*
+ *				verify_path				     *
+ *===========================================================================*/
+int verify_path(path, ino, attr, stale)
+char path[PATH_MAX];
+struct inode *ino;
+struct sffs_attr *attr;
+int *stale;
+{
+/* Given a path, and the inode associated with that path, verify if the inode
+ * still matches the real world. Obtain the attributes of the file identified
+ * by the given path, and see if they match. If not, possibly mark the inode
+ * as deleted and return an error. Only upon success is the inode guaranteed
+ * to be usable.
+ *
+ * The caller must set the a_mask field of the passed attr struct.
+ * If 'stale' is not NULL, the value it points to must be initialized to 0,
+ * and will be set to 1 if the path was valid but the inode wasn't.
+ */
+  int r;
+
+  attr->a_mask |= SFFS_ATTR_MODE;
+
+  r = sffs_table->t_getattr(path, attr);
+
+  dprintf(("%s: verify_path: getattr('%s') returned %d\n",
+	sffs_name, path, r));
+
+  if (r != OK) {
+	/* If we are told that the path does not exist, delete the inode */
+	if (r == ENOENT || r == ENOTDIR)
+		del_dentry(ino);
+
+	return r; /* path isn't valid */
+  }
+
+  /* If the file type (reg, dir) isn't what we thought, delete the inode */
+  if ((ino->i_flags & I_DIR) != MODE_TO_DIRFLAG(attr->a_mode)) {
+	del_dentry(ino);
+
+	if (stale != NULL) *stale = 1;
+	return ENOENT; /* path is valid, inode wasn't */
+  }
+
+  return OK; /* path and inode are valid */
+}
+
+/*===========================================================================*
+ *				verify_inode				     *
+ *===========================================================================*/
+int verify_inode(ino, path, attr)
+struct inode *ino;		/* inode to verify */
+char path[PATH_MAX];		/* buffer in which to store the path */
+struct sffs_attr *attr;		/* buffer for attributes, or NULL */
+{
+/* Given an inode, construct a path identifying the inode, and check whether
+ * that path is still valid for that inode (as far as we can tell). As a side
+ * effect, store attributes in the given attribute structure if not NULL (its
+ * a_mask member must then be set).
+ */
+  struct sffs_attr attr2;
+  int r;
+
+  if ((r = make_path(path, ino)) != OK) return r;
+
+  if (attr == NULL) {
+	attr2.a_mask = 0;
+
+	attr = &attr2;
+  }
+
+  return verify_path(path, ino, attr, NULL);
+}
+
+/*===========================================================================*
+ *				verify_dentry				     *
+ *===========================================================================*/
+int verify_dentry(parent, name, path, res_ino)
+struct inode *parent;		/* parent inode: the inode to verify */
+char name[NAME_MAX+1];		/* the given directory entry path component */
+char path[PATH_MAX];		/* buffer to store the resulting path in */
+struct inode **res_ino;		/* pointer for addressed inode (or NULL) */
+{
+/* Given a directory inode and a name, construct a path identifying that
+ * directory entry, check whether the path to the parent is still valid, and
+ * check whether there is an inode pointed to by the full path. Upon success,
+ * res_ino will contain either the inode for the full path, with increased
+ * refcount, or NULL if no such inode exists.
+ */
+  int r;
+
+  if ((r = verify_inode(parent, path, NULL)) != OK)
+	return r;
+
+  dprintf(("%s: verify_dentry: given path is '%s', name '%s'\n",
+	sffs_name, path, name));
+
+  if ((r = push_path(path, name)) != OK)
+	return r;
+
+  dprintf(("%s: verify_dentry: path now '%s'\n", sffs_name, path));
+
+  *res_ino = lookup_dentry(parent, name);
+
+  return OK;
+}