ljfa-ag / libnbtplusplus

A C++ library for Minecraft's file format NBT

This repository is not being maintained anymore, please refer to one of the active forks instead, for example PrismLauncher/libnbtplusplus.

libnbt++ 2

libnbt++ is a free C++ library for Minecraft's file format Named Binary Tag (NBT). It can read and write compressed and uncompressed NBT files and provides a code interface for working with NBT data.

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libnbt++2 is a remake of the old libnbt++ library with the goal of making it more easily usable and fixing some problems. The old libnbt++ especially suffered from a very convoluted syntax and boilerplate code needed to work with NBT data.

libnbtplusplus's Issues

Hi, "fatal error: 'nbt_export.h' file not found", I cannot find out the "nbt_export.h"

please. as title, I got "fatal error: 'nbt_export.h' file not found" error.
CMake:

In file included from ...nbt_tags.h:20:
In file included from ...tag_primitive.h:23:
In file included from ...crtp_tag.h:23:
...tag.h:26:10: fatal error: 'nbt_export.h' file not found

so i cannot compile it, is that common? I am confuse..

Little endian negative long encoding doesn't match Minecraft

I've found that Minecraft Bedrock Edition encodes negative little endian longs different than expected:
For example, creating a level with seed -123456789 will encode it in level.dat as EB 32 A4 F8 00 00 00 00, which is read by this library as 4171510507.
The same can be seen with the worldStartCount value in level.dat, on a newly generated world it's encoded as FE FF FF FF 00 00 00 00, apparently meaning -2.

With positive values, such as any positive seed, or the timestamp in LastPlayed it seems to work correctly, presumably because they values themselves aren't bigger than 32-bit.

tl;dr:

name	value in level.dat	read by minecraft	read by libnbtplusplus	correct?
RandomSeed	EB32A4F800000000	-123456789	4171510507	👎
RandomSeed	15CD5B0700000000	123456789	123456789	👍
worldStartCount	FEFFFFFF00000000	-2?	4294967294	👎
LastPlayed	CF94015B00000000	2018-05-20	1526830287	👍

This is based on level.dat files from different versions of Minecraft 1.2 to 1.4 for iOS and Windows 10.
It seems Minecraft is treating the 64-bit long as 32-bit, and ignoring the rest, it seems related to this minecraft bug: https://bugs.mojang.com/browse/MCPE-7091?jql=text%20~%20%22TAG_Long%22, which was ultimately resolved by limiting the seed to 32 bits.

Better unit tests and a real testing framework

Like Cppunit

Make some functions inline

Right now, most functions are defined in source files, even if they're small, preventing the compiler from inlining them. Link-time optimization is not guaranteed, so some of the definitions should maybe be moved to the header files.

Better exception throwing

Especially the bad_cast exceptions should get more meaningful messages

Support for long arrays

Minecraft 1.13 adds a new NBT LongArray tag which stores 64-bit signed integer arrays, which aren't yet supported by the library

Documentation & Conan support

Hi,
I'd really love to use your library but I'm stopped by the fact it lacks of documentation and I'm struggling also including it in my Conan project.

I'm willing to do the dirty job to post your lib on Conan Center, but I'd like to know if the version that is currently on master is working without any issue and could be defined as 1.0, or should I pick the branch called v1.

I will manage to understand the library by just reading the code, but for future users it would be helpful to have a minimalist documentation.

The ability to read and write gzip-compressed tags

For now libraries like Boost::Iostreams or Gzstream can be used for that purpose.

Requires documentation

While this is a resourceful tool, I can’t find anything that lets me know how to use it. I’m not sure how to write or read NBT files either.

Incorporate changes done in a manual fork

Hello, I started using this library in MultiMC, but had to make some changes:

• Make it a shared library instead of a static one (because of LGPL)
• Fix build on OSX and Windows because of the above
• Make the build system a bit more adapted to MultiMC integration

I'll try to get it into a decent repo again so you can use it.

See tracking issue on my end:
MultiMC/Launcher#1229

6 CxxTests fail

I ran CxxTest on the LibNBT++ library, but 6 of the 34 tests fail. The files appear to be read correctly as no file-related exceptions appear to be thrown, however the data returned does not meet the assertions in those tests.

These are the tests that failed:

• endian_str_test::test_uint
• read_test::test_read_bigtest
• read_test::test_read_littletest
• zlibstream_test::test_inflate_zlib
• zlibstream_test::test_inflate_open
• zlibstream_test::test_deflate_closed

I am using Windows 8, Visual Studio Community 2019, CxxTest 4.4, and zlib 1.2.11.

Here is the full log from running those tests.