Calculate CRC for tags on save. (#53)

CHANGELOG.MD

@@ -4,7 +4,10 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
-## [2.7.4]
+## [2.8.0]
+### Added
+ - CRCs of tags are now properly calculated on save. Use the first bit on offset 48 to determine if a tag is edited by reclaimer. (If not using this library.)
+
 ### Changed
  - safe_mode: Fix IGNORE_SAFE_MODE flag being retrieved from an incorrect location.
      - safe_mode: Fix bitmaps with permutation counts over 2048 getting pruned.

reclaimer/__init__.py

@@ -13,7 +13,7 @@
 __author__ = "Devin Bobadilla, Michelle van der Graaf"
 #           YYYY.MM.DD
 __date__ = "2020.03.07"
-__version__ = (2, 7, 4)
+__version__ = (2, 8, 0)
 __website__ = "https://github.com/Sigmmma/reclaimer"
 __all__ = (
     "animation", "bitmaps", "h2", "h3", "halo_script", "hek", "meta", "misc",

reclaimer/common_descs.py

@@ -565,7 +565,7 @@ def anim_src_func_per_pha_sca_rot_macro(name, **desc):
     UEnum32("tag_class",
         GUI_NAME="tag_class", INCLUDE=valid_tags, EDITABLE=False
         ),
-    UInt32("checksum", DEFAULT=0x4D6F7A7A, EDITABLE=False),
+    UInt32("checksum", DEFAULT=0, EDITABLE=False),
     UInt32("header_size",  DEFAULT=64, EDITABLE=False),
     BBool64("flags",
         "edited_with_mozz",
@@ -813,7 +813,7 @@ def blam_header_os(tagid, version=1):
     UEnum32("tag_class",
         GUI_NAME="tag_class", INCLUDE=valid_tags_os, EDITABLE=False
         ),
-    UInt32("checksum", DEFAULT=0x4D6F7A7A, EDITABLE=False),
+    UInt32("checksum", DEFAULT=0, EDITABLE=False),
     UInt32("header_size", DEFAULT=64, EDITABLE=False),
     Bool64("flags",
         "edited_with_mozz",

reclaimer/h2/common_descs.py

@@ -244,7 +244,7 @@ def h2_blam_header(tagid, version=1):
     UEnum32("tag class",
         GUI_NAME="tag class", INCLUDE=valid_h2_tags, EDITABLE=False
         ),
-    UInt32("checksum", DEFAULT=0x4D6F7A7A, EDITABLE=False),
+    UInt32("checksum", DEFAULT=0, EDITABLE=False),
     UInt32("header size", DEFAULT=64, EDITABLE=False),
     Bool64("flags",
         "edited with mozz",

reclaimer/h3/common_descs.py

@@ -132,7 +132,7 @@ def h3_blam_header(tagid, version=1):
     UEnum32("tag class",
         GUI_NAME="tag class", INCLUDE=valid_h3_tags, EDITABLE=False
         ),
-    UInt32("checksum", DEFAULT=0x4D6F7A7A, EDITABLE=False),
+    UInt32("checksum", DEFAULT=0, EDITABLE=False),
     UInt32("header size", DEFAULT=64, EDITABLE=False),
     Bool64("flags",
         "edited with mozz",

reclaimer/hek/defs/objs/tag.py

@@ -6,21 +6,63 @@
 # Reclaimer is free software under the GNU General Public License v3.0.
 # See LICENSE for more information.
 #
+from pathlib import Path
 
 from supyr_struct.defs.constants import DEFAULT
 from supyr_struct.tag import Tag
 
+from reclaimer.util import calc_halo_crc32
+
 class HekTag(Tag):
     def __init__(self, **kwargs):
         self.calc_pointers = False
         Tag.__init__(self, **kwargs)
 
+    def serialize(self, **kwargs):
+        '''
+        Overload of the supyr serialization function that retroactively adds
+        a CRC to the tag.
+        '''
+        head = self.data.blam_header
+        filepath = kwargs.get('filepath', self.filepath)
+        buffer = kwargs.get('buffer', None)
+
+        # Run the normal serialization.
+        result = Tag.serialize(self, **kwargs)
+
+        # If there is neither a buffer or filepath just return the result.
+        if (buffer is None) and (not filepath):
+            return result
+
+        # Prefer to use the buffer as that is how Tag.serialize does it.
+        f = buffer
+        if buffer is None:
+            f = Path(filepath).open('rb+')
+
+        # Calculate the crc from after the header to the end.
+        crc = calc_halo_crc32(f, offset=head.get_desc('SIZE'))
+        # Write the crc to the offset of the checksum value in the header.
+        # The way we retrieve this offset from supyr is insane.
+        attr_index = head.get_desc('NAME_MAP')['checksum']
+        f.seek(head.get_desc('ATTR_OFFS')[attr_index])
+        f.write(crc.to_bytes(4, byteorder='big', signed=False))
+        # Flush the stream.
+        f.flush()
+        # Only close if it is a file. Because the only case where we own
+        # this buffer is if there was no buffer kwarg.
+        if not buffer:
+            f.close()
+
+        # Update the tag object so it won't have to be deserialized again.
+        head.checksum = crc
+        return result
+
     def calc_internal_data(self):
         # recalculate the header data
         head = self.data.blam_header
 
         head.tag_class.data = head.tag_class.get_desc(DEFAULT)
-        head.checksum = head.get_desc(DEFAULT, 'checksum')
+        head.flags.edited_with_mozz = True
         head.header_size = head.get_desc(DEFAULT, 'header_size')
         head.version = head.get_desc(DEFAULT, 'version')
         head.integrity0 = head.get_desc(DEFAULT, 'integrity0')

reclaimer/shadowrun_prototype/common_descs.py

@@ -57,7 +57,7 @@ def blam_header(tagid, version=1):
     UEnum32("tag_class",
         GUI_NAME="tag_class", INCLUDE=sr_valid_tags, EDITABLE=False
         ),
-    UInt32("checksum", DEFAULT=0x4D6F7A7A, EDITABLE=False),
+    UInt32("checksum", DEFAULT=0, EDITABLE=False),
     UInt32("header_size",  DEFAULT=64, EDITABLE=False),
     BBool64("flags",
         "edited_with_mozz",

reclaimer/stubbs/common_descs.py

@@ -172,7 +172,7 @@ def blam_header_stubbs(tagid, version=1):
     UEnum32("tag_class",
         GUI_NAME="tag_class", INCLUDE=stubbs_valid_tags, EDITABLE=False
         ),
-    UInt32("checksum", DEFAULT=0x4D6F7A7A, EDITABLE=False),
+    UInt32("checksum", DEFAULT=0, EDITABLE=False),
     UInt32("header_size",  DEFAULT=64, EDITABLE=False),
     BBool64("flags",
         "edited_with_mozz",

reclaimer/util/__init__.py

@@ -1,4 +1,5 @@
 import re
+import zlib
 
 from math import log
 
@@ -124,4 +125,10 @@ def is_valid_ascii_name_str(string):
             return False
     return True
 
+def calc_halo_crc32(buffer, offset=None, size=None, crc=0xFFffFFff):
+    if offset is not None:
+        buffer.seek(offset)
+
+    return zlib.crc32(buffer.read(size), crc ^ 0xFFffFFff) ^ 0xFFffFFff
+
 del re