From fea949f1f46c27bf69b43dfb8ef1402e090e890f Mon Sep 17 00:00:00 2001
From: Max Wash <mbswash@gmail.com>
Date: Sat, 1 Feb 2025 22:12:46 +0000
Subject: [PATCH] start packing some binary image structures

---
 src/bin.h  | 86 +++++++++++++++++++++++++++++-------------------------
 src/misc.h | 12 ++++++++
 2 files changed, 58 insertions(+), 40 deletions(-)
 create mode 100644 src/misc.h

diff --git a/src/bin.h b/src/bin.h
index 0cc8fe9..b695c24 100644
--- a/src/bin.h
+++ b/src/bin.h
@@ -2,6 +2,7 @@
 #define BIN_H_
 
 #include <blue/core/endian.h>
+#include "misc.h"
 
 #define EC3_SIGNATURE            0x45433358
 
@@ -34,7 +35,7 @@
 #define EC3_TAG_ENCRYPTED        0x00000004u
 
 /* 32K per cluster group */
-#define EC3_CLUSTERS_PER_GROUP   1635
+#define EC3_CLUSTERS_PER_GROUP   1637
 /* 1K per extent group */
 #define EC3_EXTENTS_PER_GROUP    36
 
@@ -67,47 +68,52 @@
 
 typedef uint8_t ec3_chunk_id[EC3_CHUNK_ID_SIZE];
 
-struct ec3_header {
-	b_i32 h_magic;
-	b_i16 h_version;
-	b_i16 h_cluster_size;
-	b_i64 h_tag_table_offset;
-	b_i64 h_extent_table_offset;
-	b_i64 h_cluster_table_offset;
-	b_i32 h_tag_count;
-	b_i32 h_extent_count;
-	b_i32 h_cluster_group_count;
-	b_i16 h_compression;
-	b_i16 h_encryption;
-	b_i64 h_app_magic;
-	uint8_t h_reserved[8];
-};
+PACK(
+	struct ec3_header {
+		b_i32 h_magic;
+		b_i16 h_version;
+		b_i16 h_cluster_size;
+		b_i64 h_tag_table_offset;
+		b_i64 h_extent_table_offset;
+		b_i64 h_cluster_table_offset;
+		b_i32 h_tag_count;
+		b_i32 h_extent_count;
+		b_i32 h_cluster_group_count;
+		b_i16 h_compression;
+		b_i16 h_encryption;
+		b_i64 h_app_magic;
+		uint8_t h_reserved[8];
+	}
+);
 
-struct ec3_cluster {
-	/* cluster identifier */
-	b_i32 c_id;
-	/* lower 32-bits of the cluster bounds */
-	b_i32 c_bounds0;
-	/* upper 32-bits of the cluster bounds */
-	b_i32 c_bounds1;
-	/* CRC-16 of the on-disk cluster data */
-	b_i16 c_checksum;
-	/* flags that apply to this cluster */
-	b_i16 c_flags;
-};
+PACK(
+	struct ec3_cluster {
+		/* cluster identifier */
+		b_i32 c_id;
+		/* lower 32-bits of the cluster bounds */
+		b_i32 c_bounds0;
+		/* upper 32-bits of the cluster bounds */
+		b_i32 c_bounds1;
+		/* CRC-16 of the on-disk cluster data */
+		b_i16 c_checksum;
+		/* flags that apply to this cluster */
+		b_i16 c_flags;
+	}
+);
 
-struct ec3_cluster_group {
-	/* the number of clusters that this group contains */
-	b_i16 g_nr_clusters;
-	uint8_t g_reserved[2];
-	/* array of clusters contained within the group. */
-	struct ec3_cluster g_clusters[EC3_CLUSTERS_PER_GROUP];
-	/* offsets to other cluster groups, relative to the start of the
-	 * cluster group table. the cluster groups form a B-tree. */
-	b_i32 g_child_offsets[EC3_CLUSTERS_PER_GROUP + 1];
-	/* pad the group out to an even 32K */
-	uint8_t g_padding[20];
-};
+PACK(
+	struct ec3_cluster_group {
+		/* the number of clusters that this group contains */
+		b_i16 g_nr_clusters;
+		uint8_t g_reserved[2];
+		/* array of clusters contained within the group. */
+		struct ec3_cluster g_clusters[EC3_CLUSTERS_PER_GROUP];
+		/* offsets to other cluster groups, relative to the start of the
+		 * cluster group table. the cluster groups form a B-tree. */
+		b_i32 g_child_offsets[EC3_CLUSTERS_PER_GROUP + 1];
+		uint8_t g_padding[20];
+	}
+);
 
 struct ec3_tag_table_entry {
 	b_i32 tag_type;
diff --git a/src/misc.h b/src/misc.h
new file mode 100644
index 0000000..49eb2e2
--- /dev/null
+++ b/src/misc.h
@@ -0,0 +1,12 @@
+#ifndef MISC_H_
+#define MISC_H_
+
+#ifdef __GNUC__
+#define PACK( __Declaration__ ) __Declaration__ __attribute__((__packed__))
+#endif
+
+#ifdef _MSC_VER
+#define PACK( __Declaration__ ) __pragma( pack(push, 1) ) __Declaration__ __pragma( pack(pop))
+#endif
+
+#endif
\ No newline at end of file