From f9894b7e0e2a2a46fffdf7274d8671fb00f98089 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers3@gmail.com>
Date: Sun, 18 Oct 2015 19:39:33 -0500
Subject: [PATCH 1/1] inode: move 'i_extra_size' to 'i_extra' buffer

Usually there will be no extra data and this will save a bit of memory.
---
 include/wimlib/inode.h | 12 ++++++++----
 src/dentry.c           | 13 ++++++++-----
 src/tagged_items.c     | 32 ++++++++++++++++++++------------
 3 files changed, 36 insertions(+), 21 deletions(-)

diff --git a/include/wimlib/inode.h b/include/wimlib/inode.h
index 51462126..ed6f9de9 100644
--- a/include/wimlib/inode.h
+++ b/include/wimlib/inode.h
@@ -10,6 +10,7 @@ struct avl_tree_node;
 struct blob_descriptor;
 struct blob_table;
 struct wim_dentry;
+struct wim_inode_extra;
 struct wim_security_data;
 struct wimfs_fd;
 
@@ -140,10 +141,7 @@ struct wim_inode {
 	 * dentry.  This should be a series of tagged items, each of which
 	 * represents a bit of extra metadata, such as the file's object ID.
 	 * See tagged_items.c for more information.  */
-	void *i_extra;
-
-	/* Size of @i_extra buffer in bytes.  If 0, there is no extra data.  */
-	size_t i_extra_size;
+	struct wim_inode_extra *i_extra;
 
 	/* Creation time, last access time, and last write time for this inode,
 	 * in 100-nanosecond intervals since 12:00 a.m UTC January 1, 1601.
@@ -230,6 +228,12 @@ struct wim_inode {
 	u32 i_next_stream_id;
 };
 
+/* Optional extra data for a WIM inode  */
+struct wim_inode_extra {
+	size_t size;	/* Size of the extra data in bytes  */
+	u8 data[];	/* The extra data  */
+};
+
 /*
  * The available reparse tags are documented at
  * http://msdn.microsoft.com/en-us/library/dd541667(v=prot.10).aspx.
diff --git a/src/dentry.c b/src/dentry.c
index 13940a32..ff1a2142 100644
--- a/src/dentry.c
+++ b/src/dentry.c
@@ -358,7 +358,8 @@ dentry_out_total_length(const struct wim_dentry *dentry)
 					dentry->d_short_name_nbytes);
 	len = ALIGN(len, 8);
 
-	len += ALIGN(inode->i_extra_size, 8);
+	if (inode->i_extra)
+		len += ALIGN(inode->i_extra->size, 8);
 
 	if (!(inode->i_attributes & FILE_ATTRIBUTE_ENCRYPTED)) {
 		/*
@@ -1187,10 +1188,12 @@ read_extra_data(const u8 *p, const u8 *end, struct wim_inode *inode)
 		p++;
 
 	if (unlikely(p < end)) {
-		inode->i_extra = memdup(p, end - p);
+		inode->i_extra = MALLOC(sizeof(struct wim_inode_extra) +
+					end - p);
 		if (!inode->i_extra)
 			return WIMLIB_ERR_NOMEM;
-		inode->i_extra_size = end - p;
+		inode->i_extra->size = end - p;
+		memcpy(inode->i_extra->data, p, end - p);
 	}
 	return 0;
 }
@@ -1774,9 +1777,9 @@ write_dentry(const struct wim_dentry * restrict dentry, u8 * restrict p)
 	while ((uintptr_t)p & 7)
 		*p++ = 0;
 
-	if (inode->i_extra_size) {
+	if (inode->i_extra) {
 		/* Extra tagged items --- not usually present.  */
-		p = mempcpy(p, inode->i_extra, inode->i_extra_size);
+		p = mempcpy(p, inode->i_extra->data, inode->i_extra->size);
 
 		/* Align to 8-byte boundary */
 		while ((uintptr_t)p & 7)
diff --git a/src/tagged_items.c b/src/tagged_items.c
index 1ed3b4a9..723773f9 100644
--- a/src/tagged_items.c
+++ b/src/tagged_items.c
@@ -74,8 +74,14 @@ inode_get_tagged_item(const struct wim_inode *inode,
 		      u32 desired_tag, u32 min_data_len)
 {
 	size_t minlen_with_hdr = sizeof(struct tagged_item_header) + min_data_len;
-	size_t len_remaining = inode->i_extra_size;
-	u8 *p = inode->i_extra;
+	size_t len_remaining;
+	u8 *p;
+
+	if (!inode->i_extra)
+		return NULL;
+
+	len_remaining = inode->i_extra->size;
+	p = inode->i_extra->data;
 
 	/* Iterate through the tagged items.  */
 	while (len_remaining >= minlen_with_hdr) {
@@ -108,26 +114,28 @@ inode_add_tagged_item(struct wim_inode *inode, u32 tag, u32 len)
 {
 	size_t itemsize;
 	size_t newsize;
-	u8 *buf;
+	struct wim_inode_extra *extra;
 	struct tagged_item_header *hdr;
 
 	/* We prepend the item instead of appending it because it's easier.  */
 
 	itemsize = sizeof(struct tagged_item_header) + ALIGN(len, 8);
-	newsize = itemsize + inode->i_extra_size;
+	newsize = itemsize;
+	if (inode->i_extra)
+		newsize += inode->i_extra->size;
 
-	buf = MALLOC(newsize);
-	if (!buf)
+	extra = MALLOC(sizeof(struct wim_inode_extra) + newsize);
+	if (!extra)
 		return NULL;
-
-	if (inode->i_extra_size) {
-		memcpy(buf + itemsize, inode->i_extra, inode->i_extra_size);
+	if (inode->i_extra) {
+		memcpy(&extra->data[itemsize], inode->i_extra->data,
+		       inode->i_extra->size);
 		FREE(inode->i_extra);
 	}
-	inode->i_extra = buf;
-	inode->i_extra_size = newsize;
+	extra->size = newsize;
+	inode->i_extra = extra;
 
-	hdr = (struct tagged_item_header *)buf;
+	hdr = (struct tagged_item_header *)extra->data;
 	hdr->tag = cpu_to_le32(tag);
 	hdr->length = cpu_to_le32(len);
 	return memset(hdr->data, 0, ALIGN(len, 8));
-- 
2.43.0