add asset extract script

.gitignore

@@ -12,6 +12,10 @@ vtable.lcf
 # Game Assets
 game/
 
+# Disk Images
+*.iso
+*.gcm
+
 # Generated documentation
 docs/doxygen/
 

tools/extract_game_assets.py

@@ -0,0 +1,123 @@
+import os
+import sys
+
+"""
+Extracts the game assets and stores them in the game folder
+Usage: `python tools/extract_game_assets.py`
+"""
+
+fstInfoPosition = 0x424
+numFileEntries = 0
+
+"""
+Returns the offset address and size of fst.bin
+"""
+def getFstInfo(handler, fstOffsetPosition):
+    fstOffset = int.from_bytes(bytearray(handler.read(4)), byteorder='big')
+    handler.seek(fstOffsetPosition + 4) # Get the size which is 4 bytes after the offset
+    fstSize = int.from_bytes(bytearray(handler.read(4)), byteorder='big')
+    return fstOffset, fstSize
+
+"""
+Parses the fst.bin into a list of dictionaries containing
+the file name, file offset into the ISO, the file size,
+and the folder structure
+"""
+def parseFstBin(fstBinBytes):
+    currentByte = 0
+    numFileEntries = int.from_bytes(fstBinBytes[10:12], byteorder='big') # fst.bin offset
+    stringTableOffset = numFileEntries * 0xC
+
+    ret = []
+
+    while currentByte != (numFileEntries*12):
+        currentByte += 12
+
+        # lazy
+        if currentByte == (numFileEntries*12):
+            break
+
+        fileFolder = fstBinBytes[currentByte]
+        filenameOffset = int.from_bytes(fstBinBytes[currentByte+1:currentByte+4], byteorder='big')
+        fileOffsetOrParentEntryNum = int.from_bytes(fstBinBytes[currentByte+4:currentByte+8], byteorder='big')
+        fileSizeOrLastEntryNum = int.from_bytes(fstBinBytes[currentByte+8:currentByte+12], byteorder='big')
+        currentFilenameOffset = stringTableOffset+filenameOffset
+
+        # Figure out the filename by checking for null string terminator
+        i = 0
+        while fstBinBytes[currentFilenameOffset+i] != 0:
+            i += 1
+
+        fileName = (fstBinBytes[currentFilenameOffset:currentFilenameOffset+i]).decode()
+
+        if fileFolder == 0:
+            ret.append({"type": "File","fileName": fileName,"fileOffset":fileOffsetOrParentEntryNum,"fileSize":fileSizeOrLastEntryNum})
+        else:
+            ret.append({"type": "Folder","folderName": fileName,"parentFolderEntryNumber": fileOffsetOrParentEntryNum, "lastEntryNumber": fileSizeOrLastEntryNum})
+        
+    return ret
+
+"""
+Write the current folder to disk and return it's name/last entry number
+"""
+def writeFolder(parsedFstBin,i):
+    folderPath = i["folderName"]+"/"
+    lastEntryNumber = i["lastEntryNumber"]
+
+    if i["parentFolderEntryNumber"] == 0:
+        if not os.path.exists(folderPath):
+            os.makedirs(folderPath)
+    else:
+        parentFolderEntry = parsedFstBin[i["parentFolderEntryNumber"]-1]
+        while True:
+            folderPath = parentFolderEntry["folderName"] + "/" + folderPath
+            if parentFolderEntry["parentFolderEntryNumber"] == 0:
+                break
+
+            nextParentFolderEntryNumber = parentFolderEntry["parentFolderEntryNumber"]
+            parentFolderEntry = parsedFstBin[nextParentFolderEntryNumber-1]
+        
+        if not os.path.exists(folderPath):
+            os.makedirs(folderPath)
+
+    return folderPath, lastEntryNumber
+
+"""
+Use the parsed fst.bin contents to write assets to file
+"""
+def writeAssets(parsedFstBin, handler):
+    # Write the folder structure and files to disc
+    j = 0
+    folderStack = []
+    folderStack.append({"folderName": "./", "lastEntryNumber": numFileEntries})
+    for i in parsedFstBin:
+        j += 1
+        if i["type"] == "Folder":
+            currentFolder, lastEntryNumber = writeFolder(parsedFstBin,i)
+            folderStack.append({"folderName": currentFolder, "lastEntryNumber": lastEntryNumber})
+        else:
+            handler.seek(i["fileOffset"])
+            with open((folderStack[-1]["folderName"]+i["fileName"]), "wb") as currentFile:
+                currentFile.write(bytearray(handler.read(i["fileSize"])))
+            
+            while folderStack[-1]["lastEntryNumber"] == j+1:
+                folderStack.pop()
+
+def main():
+    with open(sys.argv[1], "rb") as f:
+        # Seek to fst offset information and retrieve it
+        f.seek(fstInfoPosition)
+        fstOffset,fstSize = getFstInfo(f,fstInfoPosition)
+
+        # Seek to fst.bin and retrieve it
+        f.seek(fstOffset)
+        fstBinBytes = bytearray(f.read(fstSize))
+
+        # Parse fst.bin
+        parsedFstBin = parseFstBin(fstBinBytes)
+
+        # Write assets to file
+        writeAssets(parsedFstBin, f)
+
+if __name__ == "__main__":
+    main()