Introduce index block version 3 with enhanced fault tolerance and previous block referencing

include/aaruformat/enums.h

@@ -210,6 +210,8 @@ typedef enum
     IndexBlock                   = 0x58444E49,
     /** Block containing the index v2 */
     IndexBlock2                  = 0x32584449,
+    /** Block containing the index v3 */
+    IndexBlock3                  = 0x33584449,
     /** Block containing logical geometry */
     GeometryBlock                = 0x4D4F4547,
     /** Block containing metadata */

include/aaruformat/structs/index.h

@@ -43,6 +43,19 @@ typedef struct IndexHeader2
     uint64_t crc64;
 } IndexHeader2;
 
+/**Header for the index, followed by entries */
+typedef struct IndexHeader3
+{
+    /**Identifier, <see cref="BlockType.Index" /> */
+    uint32_t identifier;
+    /**How many entries follow this header */
+    uint64_t entries;
+    /**CRC64-ECMA of the index */
+    uint64_t crc64;
+    /**Pointer to the previous index header */
+    uint64_t previous;
+} IndexHeader3;
+
 /**Index entry */
 typedef struct IndexEntry
 {