From 19fd5bbc4f64cc8bf735f7c2c0bb864876998cf4 Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers3@gmail.com>
Date: Fri, 17 May 2013 22:50:12 -0500
Subject: [PATCH 1/1] Make padded structures work properly with MinGW

---
 Makefile.am        | 5 +++++
 src/dentry.c       | 8 ++++++++
 src/header.c       | 3 ++-
 src/lookup_table.c | 6 ++++++
 4 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/Makefile.am b/Makefile.am
index 75ed9716..45a85af8 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -7,6 +7,11 @@ AM_CFLAGS	= -std=gnu99 -Wmissing-prototypes -Wstrict-prototypes	\
 		  -Werror-implicit-function-declaration			\
 		  -fno-common -Wundef -Wno-pointer-sign
 
+if WINDOWS_NATIVE_BUILD
+# This option is needed to make packed structures work as expected
+# with gcc 4.7+ (mingw) on Windows.
+AM_CFLAGS += -mno-ms-bitfields
+endif
 
 lib_LTLIBRARIES = libwim.la
 
diff --git a/src/dentry.c b/src/dentry.c
index 47a6175d..f986f9df 100644
--- a/src/dentry.c
+++ b/src/dentry.c
@@ -70,6 +70,8 @@ struct wim_ads_entry_on_disk {
 	utf16lechar stream_name[];
 } _packed_attribute;
 
+#define WIM_ADS_ENTRY_DISK_SIZE 38
+
 /* WIM directory entry (on-disk format) */
 struct wim_dentry_on_disk {
 	le64 length;
@@ -105,6 +107,8 @@ struct wim_dentry_on_disk {
 	/*utf16lechar short_name[];*/
 } _packed_attribute;
 
+#define WIM_DENTRY_DISK_SIZE 102
+
 /* Calculates the unaligned length, in bytes, of an on-disk WIM dentry that has
  * a file name and short name that take the specified numbers of bytes.  This
  * excludes any alternate data stream entries that may follow the dentry. */
@@ -1387,6 +1391,8 @@ read_ads_entries(const u8 * restrict p, struct wim_inode * restrict inode,
 	struct wim_ads_entry *ads_entries;
 	int ret;
 
+	BUILD_BUG_ON(sizeof(struct wim_ads_entry_on_disk) != WIM_ADS_ENTRY_DISK_SIZE);
+
 	/* Allocate an array for our in-memory representation of the alternate
 	 * data stream entries. */
 	num_ads = inode->i_num_ads;
@@ -1531,6 +1537,8 @@ read_dentry(const u8 * restrict metadata_resource, u64 metadata_resource_len,
 	const struct wim_dentry_on_disk *disk_dentry =
 			(const struct wim_dentry_on_disk*)p;
 
+	BUILD_BUG_ON(sizeof(struct wim_dentry_on_disk) != WIM_DENTRY_DISK_SIZE);
+
 	if ((uintptr_t)p & 7)
 		WARNING("WIM dentry is not 8-byte aligned");
 
diff --git a/src/header.c b/src/header.c
index 5a665fc2..5b164161 100644
--- a/src/header.c
+++ b/src/header.c
@@ -120,6 +120,8 @@ read_header(const tchar *filename, int in_fd,
 {
 	struct wim_header_disk disk_hdr _aligned_attribute(8);
 
+	BUILD_BUG_ON(sizeof(struct wim_header_disk) != WIM_HEADER_DISK_SIZE);
+
 	DEBUG("Reading WIM header from \"%"TS"\"", filename);
 
 	if (full_pread(in_fd, &disk_hdr, sizeof(disk_hdr), 0) != sizeof(disk_hdr)) {
@@ -132,7 +134,6 @@ read_header(const tchar *filename, int in_fd,
 		return WIMLIB_ERR_NOT_A_WIM_FILE;
 	}
 
-	BUILD_BUG_ON(sizeof(struct wim_header_disk) != WIM_HEADER_DISK_SIZE);
 	if (le32_to_cpu(disk_hdr.hdr_size) != sizeof(struct wim_header_disk)) {
 		ERROR("\"%"TS"\": Header size is invalid (%u bytes)",
 		      filename, le32_to_cpu(disk_hdr.hdr_size));
diff --git a/src/lookup_table.c b/src/lookup_table.c
index f3d8c537..a24cf688 100644
--- a/src/lookup_table.c
+++ b/src/lookup_table.c
@@ -365,6 +365,8 @@ struct wim_lookup_table_entry_disk {
 	u8 hash[SHA1_HASH_SIZE];
 } _packed_attribute;
 
+#define WIM_LOOKUP_TABLE_ENTRY_DISK_SIZE 50
+
 /*
  * Reads the lookup table from a WIM file.
  *
@@ -382,6 +384,10 @@ read_lookup_table(WIMStruct *w)
 	struct wim_lookup_table_entry_disk
 			table_buf[BUFFER_SIZE / sizeof(struct wim_lookup_table_entry_disk)]
 				_aligned_attribute(8);
+
+	BUILD_BUG_ON(sizeof(struct wim_lookup_table_entry_disk) !=
+		     WIM_LOOKUP_TABLE_ENTRY_DISK_SIZE);
+
 	off_t offset;
 	size_t buf_entries_remaining;
 	const struct wim_lookup_table_entry_disk *disk_entry;
-- 
2.43.0