Made accessing reparse directories through internal plugins

When the bit 28 of a reparse tag is set on a directory, the reparse
information should be ignored and the directory should be accessed
the usual way (this setting is new to Windows 10). In such a situation
access to the directory through an internal plugin rather than through
an external one.
The same policy applies to REPARSE_TAG_WCI which had been defined
earlier without the bit 28 being set.

include/ntfs-3g/layout.h

@@ -2403,22 +2403,23 @@ typedef struct {
  *
  * 1. The least significant 16 bits (i.e. bits 0 to 15) specify the type of
  *    the reparse point.
- * 2. The 13 bits after this (i.e. bits 16 to 28) are reserved for future use.
- * 3. The most significant three bits are flags describing the reparse point.
+ * 2. The 12 bits after this (i.e. bits 16 to 27) are reserved for future use.
+ * 3. The most significant four bits are flags describing the reparse point.
  *    They are defined as follows:
+ *	bit 28: Directory bit. If set, the directory is not a surrogate
+ *		and can be used the usual way.
  *	bit 29: Name surrogate bit. If set, the filename is an alias for
  *		another object in the system.
  *	bit 30: High-latency bit. If set, accessing the first byte of data will
  *		be slow. (E.g. the data is stored on a tape drive.)
  *	bit 31: Microsoft bit. If set, the tag is owned by Microsoft. User
  *		defined tags have to use zero here.
- * 4. However, on Windows 10 :
+ * 4. Moreover, on Windows 10 :
  *	Some flags may be used in bits 12 to 15 to further describe the
- *	reparse point, and bit 28 may be set, probably to signal the
- *	presence of these flags.
+ *	reparse point.
  */
 typedef enum {
-	IO_REPARSE_TAG_WITH_FLAGS	= const_cpu_to_le32(0x10000000),
+	IO_REPARSE_TAG_DIRECTORY	= const_cpu_to_le32(0x10000000),
 	IO_REPARSE_TAG_IS_ALIAS		= const_cpu_to_le32(0x20000000),
 	IO_REPARSE_TAG_IS_HIGH_LATENCY	= const_cpu_to_le32(0x40000000),
 	IO_REPARSE_TAG_IS_MICROSOFT	= const_cpu_to_le32(0x80000000),

ntfsprogs/ntfsinfo.c

@@ -413,9 +413,7 @@ static const char *reparse_type_name(le32 tag)
 	const char *name;
 	le32 seltag;
 
-	seltag = tag;
-	if (tag & IO_REPARSE_TAG_WITH_FLAGS)
-		seltag &= IO_REPARSE_PLUGIN_SELECT;
+	seltag = tag & IO_REPARSE_PLUGIN_SELECT;
 	switch (seltag) {
 	case IO_REPARSE_TAG_MOUNT_POINT :
 		name = " (mount point)";

src/lowntfs-3g.c

@@ -4568,6 +4568,7 @@ int main(int argc, char *argv[])
 
 #ifndef DISABLE_PLUGINS
 	register_internal_reparse_plugins();
+	register_directory_plugins(ctx);
 #endif /* DISABLE_PLUGINS */
 
 	se = mount_fuse(parsed_options);

src/ntfs-3g.c

@@ -4304,6 +4304,7 @@ int main(int argc, char *argv[])
 
 #ifndef DISABLE_PLUGINS
 	register_internal_reparse_plugins();
+	register_directory_plugins(ctx);
 #endif /* DISABLE_PLUGINS */
 
 	fh = mount_fuse(parsed_options);

src/ntfs-3g_common.c

@@ -36,6 +36,10 @@
 #include <string.h>
 #endif
 
+#ifdef HAVE_FCNTL_H
+#include <fcntl.h>
+#endif
+
 #ifdef HAVE_LIMITS_H
 #include <limits.h>
 #endif
@@ -766,6 +770,108 @@ exit :
 
 #ifndef DISABLE_PLUGINS
 
+/*
+ *		Get attribute information for reparse directories
+ *
+ *	Reparse directories have a reparse tag which should be ignored.
+ */
+
+static int directory_getattr(ntfs_inode *ni, const REPARSE_POINT *reparse,
+			      struct stat *stbuf)
+{
+	static ntfschar I30[] =
+		{ const_cpu_to_le16('$'), const_cpu_to_le16('I'),
+		  const_cpu_to_le16('3'), const_cpu_to_le16('0') };
+	ntfs_attr *na;
+	int res;
+
+	res = -EOPNOTSUPP;
+	if (ni && reparse && stbuf
+		&& ((reparse->reparse_tag == IO_REPARSE_TAG_WCI)
+		|| ((reparse->reparse_tag & IO_REPARSE_TAG_DIRECTORY)
+		    && !(reparse->reparse_tag & IO_REPARSE_TAG_IS_ALIAS)))
+	    && (ni->mrec->flags & MFT_RECORD_IS_DIRECTORY)) {
+			/* Directory */
+		stbuf->st_mode = S_IFDIR | 0555;
+		/* get index size, if not known */
+		if (!test_nino_flag(ni, KnownSize)) {
+			na = ntfs_attr_open(ni, AT_INDEX_ALLOCATION, I30, 4);
+			if (na) {
+				ni->data_size = na->data_size;
+				ni->allocated_size = na->allocated_size;
+				set_nino_flag(ni, KnownSize);
+				ntfs_attr_close(na);
+			}
+		}
+		stbuf->st_size = ni->data_size;
+		stbuf->st_blocks = ni->allocated_size >> 9;
+		stbuf->st_nlink = 1;	/* Make find(1) work */
+		res = 0;
+	}
+	/* Not a directory, or another error occurred */
+	return (res);
+}
+
+/*
+ *		Open a reparse directory for reading
+ *
+ *	Currently no reading context is created.
+ */
+
+static int directory_opendir(ntfs_inode *ni, const REPARSE_POINT *reparse,
+			   struct fuse_file_info *fi)
+{
+	int res;
+
+	res = -EOPNOTSUPP;
+	if (ni && reparse && fi
+	    && ((reparse->reparse_tag == IO_REPARSE_TAG_WCI)
+		|| ((reparse->reparse_tag & IO_REPARSE_TAG_DIRECTORY)
+		    && !(reparse->reparse_tag & IO_REPARSE_TAG_IS_ALIAS)))
+	    && (ni->mrec->flags & MFT_RECORD_IS_DIRECTORY)
+	    && ((fi->flags & O_ACCMODE) == O_RDONLY))
+		res = 0;
+	return (res);
+}
+
+/*
+ *		Release a reparse directory
+ *
+ *	Should never be called, as no reading context was defined.
+ */
+
+static int directory_release(ntfs_inode *ni __attribute__((unused)),
+			   const REPARSE_POINT *reparse __attribute__((unused)),
+			   struct fuse_file_info *fi __attribute__((unused)))
+{
+	return 0;
+}
+
+/*
+ *		Read an open reparse directory
+ *
+ *	Returns 0 or a negative error code
+ */
+
+static int directory_readdir(ntfs_inode *ni, const REPARSE_POINT *reparse,
+			s64 *pos, void *fillctx, ntfs_filldir_t filldir,
+			struct fuse_file_info *fi __attribute__((unused)))
+{
+	int res;
+
+	res = -EOPNOTSUPP;
+	if (ni && reparse && pos && fillctx && filldir
+	    && ((reparse->reparse_tag == IO_REPARSE_TAG_WCI)
+	        || ((reparse->reparse_tag & IO_REPARSE_TAG_DIRECTORY)
+	    	    && !(reparse->reparse_tag & IO_REPARSE_TAG_IS_ALIAS)))
+	    && (ni->mrec->flags & MFT_RECORD_IS_DIRECTORY)) {
+		res = 0;
+		if (ntfs_readdir(ni, pos, fillctx, filldir))
+			res = -errno;
+	}
+	return (res);
+}
+
 int register_reparse_plugin(ntfs_fuse_context_t *ctx, le32 tag,
 				const plugin_operations_t *ops, void *handle)
 {
@@ -773,14 +879,16 @@ int register_reparse_plugin(ntfs_fuse_context_t *ctx, le32 tag,
 	int res;
 
 	res = -1;
-	plugin = (plugin_list_t*)ntfs_malloc(sizeof(plugin_list_t));
-	if (plugin) {
-		plugin->tag = tag;
-		plugin->ops = ops;
-		plugin->handle = handle;
-		plugin->next = ctx->plugins;
-		ctx->plugins = plugin;
-		res = 0;
+	if (ctx) {
+		plugin = (plugin_list_t*)ntfs_malloc(sizeof(plugin_list_t));
+		if (plugin) {
+			plugin->tag = tag;
+			plugin->ops = ops;
+			plugin->handle = handle;
+			plugin->next = ctx->plugins;
+			ctx->plugins = plugin;
+			res = 0;
+		}
 	}
 	return (res);
 }
@@ -810,8 +918,8 @@ const struct plugin_operations *select_reparse_plugin(ntfs_fuse_context_t *ctx,
 	if (reparse) {
 		tag = reparse->reparse_tag;
 		seltag = tag;
-		if (tag & IO_REPARSE_TAG_WITH_FLAGS)
-			seltag &= IO_REPARSE_PLUGIN_SELECT;
+		if (tag & IO_REPARSE_TAG_DIRECTORY)
+			seltag &= IO_REPARSE_TAG_DIRECTORY;
 		for (plugin=ctx->plugins; plugin && (plugin->tag != seltag);
 						plugin = plugin->next) { }
 		if (plugin) {
@@ -873,6 +981,23 @@ void close_reparse_plugins(ntfs_fuse_context_t *ctx)
 	}
 }
 
+void register_directory_plugins(ntfs_fuse_context_t *ctx)
+{
+	static const struct plugin_operations ops = {
+		.getattr = directory_getattr,
+		.release = directory_release,
+		.opendir = directory_opendir,
+		.readdir = directory_readdir,
+	} ;
+
+	if (ctx) {
+		register_reparse_plugin(ctx, IO_REPARSE_TAG_WCI,
+						&ops, (void*)NULL);
+		register_reparse_plugin(ctx, IO_REPARSE_TAG_DIRECTORY,
+						&ops, (void*)NULL);
+	}
+}
+
 #endif /* DISABLE_PLUGINS */
 
 #ifdef HAVE_SETXATTR

src/ntfs-3g_common.h

@@ -211,7 +211,7 @@ const struct plugin_operations *select_reparse_plugin(ntfs_fuse_context_t *ctx,
 				ntfs_inode *ni, REPARSE_POINT **reparse);
 int register_reparse_plugin(ntfs_fuse_context_t *ctx, le32 tag,
                                 const plugin_operations_t *ops, void *handle);
-
+void register_directory_plugins(ntfs_fuse_context_t *ctx);
 #endif /* DISABLE_PLUGINS */
 
 #endif /* _NTFS_3G_COMMON_H */