Create script to convert files between .arc and .zip

arcconv.py

@@ -0,0 +1,81 @@
+import sys, struct
+from zipfile import ZipFile, Path
+from io import BytesIO
+
+
+def usage(exe_name: str):
+    print(f"usage: {exe_name} <command> <infile> <outfile>")
+    print("  command: either arc2zip or zip2arc")
+    sys.exit(1)
+
+
+def main():
+    exe_name = sys.argv[0]
+    if len(sys.argv) != 4: usage(exe_name)
+    command = sys.argv[1]
+    in_filename = sys.argv[2]
+    out_filename = sys.argv[3]
+
+    if command == "arc2zip":
+        arc_to_zip(in_filename, out_filename)
+    elif command == "zip2arc":
+        zip_to_arc(in_filename, out_filename)
+    else:
+        usage(exe_name)
+
+
+def arc_to_zip(in_filename: str, out_filename: str):
+    with open(in_filename, "rb") as file:
+        data = file.read()
+        buf = BytesIO(data)
+
+    with ZipFile(out_filename, "w") as zipfile:
+        entry_count = struct.unpack(">I", buf.read(4))[0]
+        files = []
+
+        for _ in range(entry_count):
+            strlen = struct.unpack(">H", buf.read(2))[0]
+            fmt = f">{strlen}s2I"
+            fmt_size = struct.calcsize(fmt)
+            (filename, offset, size) = struct.unpack(fmt, buf.read(fmt_size))
+            filename = filename.decode("UTF-8").strip("\0").replace("\\", "/")
+            file_path = Path(zipfile, filename)
+            files.append((filename, data[offset:offset + size]))
+
+#        files.sort(key=lambda pair: pair[0])
+        for filename, contents in files:
+            zipfile.writestr(filename, contents)
+
+
+def zip_to_arc(in_filename: str, out_filename: str):
+    data_buf = bytearray()
+
+    with open(out_filename, "wb") as out_file:
+        files = []
+
+        with ZipFile(in_filename, "r") as zip_file:
+            files.extend((file.filename, zip_file.read(file)) for file in zip_file.filelist)
+
+#        files.sort(key=lambda pair: pair[0])
+
+        header_length = (
+            sum(len(file[0].encode('utf-8')) for file in files)
+            + len(files) * struct.calcsize(f">H2I")
+            + struct.calcsize("I")
+        )
+
+        out_file.write(struct.pack(">I", len(files)))
+
+        for filename, contents in files:
+            offset = header_length + len(data_buf)
+            file_path = filename.replace("/", "\\").encode('utf-8')
+            out_file.write(struct.pack(
+                f">H{len(file_path)}s2I", len(file_path), file_path, offset, len(contents)
+            ))
+            data_buf.extend(contents)
+
+        out_file.write(data_buf)
+
+if __name__ == "__main__":
+    main()
+