test/nbt_size_helpers: Implement tests for valid input

I stumbled over this when writing the unit test. Previously, it would return
an error code but explicitly mark it as not being an error. This was intended
behavior but I decided to change it because I didn’t anticipate it when writing
the test.

Technically `ErrorOr<T>` can be used to pass any message alongside `T`,
but practically, it is reasonable to assume that the error code is
`ErrorCodes::SUCCESS` when `isError` is false. Therefore, this feature
should be really only used in the weirdest edge cases - if at all.
Even then, it is most likely still preferable to flag it as an error and
just hand the resulting `T` back using the long constructor
`ErrorOr<T>(bool, uint8_t, T)`.

scripts/build.sh

@@ -33,7 +33,7 @@ fi
 
 # `.cpp` files in src/lib will be automatically picked up and compiled into
 # dynamically linked libraries.
-echo "Building libs..."
+echo ">>> Building libs..."
 create_directory bin/lib
 for lib in $(find ./src/lib -name "*.cpp"); do
     COMPILE_COMMAND="$CXX_WITH_FLAGS -I ./include -fPIC -shared -o $(sed -e 's/^.\/src/.\/bin/;s/cpp$/so/' <<< $lib) $lib"
@@ -55,7 +55,7 @@ wait
 # How to run a tool: specify the library path to use for the dynamic linker
 #   when running a program
 # Example: LD_LIBRARY_PATH=bin/lib bin/tools/dumpnbt
-echo "Building tools..."
+echo ">>> Building tools..."
 create_directory bin/tools
 # add compile commands to this array
 COMPILE_COMMANDS=(

scripts/clean.sh

@@ -15,6 +15,8 @@
 # version 3 along with this program.
 # If not, see https://www.gnu.org/licenses/agpl-3.0.en.html
 
+echo ">>> Cleaning build files..."
+
 source scripts/lib.sh
 
 remove ./bin

scripts/clean_dependencies.sh

@@ -17,7 +17,7 @@
 
 source scripts/lib.sh
 
-echo "Checking download cache for unneeded or corrupted files..."
+echo ">>> Checking download cache for unneeded or corrupted files..."
 for file in $(ls .download_cache); do
     #TODO: remove if unknown shasum
     if grep $file scripts/setup_project.sh >/dev/null 2>&1; then
@@ -32,7 +32,8 @@ for file in $(ls .download_cache); do
         rm ".download_cache/$file"
     fi
 done
-echo ""
+echo "
+>>> Cleaning dependencies..."
 
 remove ./dependencies
 create_directory ./dependencies

scripts/setup_project.sh

@@ -72,9 +72,7 @@ function download {
     fi
 }
 
-echo "Cleaning build files..."
 scripts/clean.sh
-echo "Cleaning dependencies..."
 scripts/clean_dependencies.sh
 
 set -e # failures are not acceptable here
@@ -82,20 +80,21 @@ create_directory dependencies/tmp
 download https://github.com/DuffsDevice/tiny-utf8/archive/refs/tags/v4.4.3.tar.gz dependencies/tmp/tiny-utf8.tar.gz 8e3f61651909c9f3105d3501932a96aa65733127fb6e7cf94cb1b0a2dff42c8f
 download https://github.com/fpagliughi/sockpp/archive/refs/tags/v0.7.1.tar.gz dependencies/tmp/sockpp.tar.gz 2e023528bebbd2ac083fc91fbe6d5c4158c3336bedbcff48f594f3b28f53b940
 
-echo -n "Extracting tiny-utf8... "
+echo -n ">>> Extracting tiny-utf8... "
 gzip -d dependencies/tmp/tiny-utf8.tar.gz
 tar -xf dependencies/tmp/tiny-utf8.tar -C dependencies
-echo "done."
+echo "done"
 
-echo -n "Extracting sockpp... "
+echo -n ">>> Extracting sockpp... "
 gzip -d dependencies/tmp/sockpp.tar.gz
 tar -xf dependencies/tmp/sockpp.tar -C dependencies
-echo "done."
-echo -n "Building sockpp... "
+echo "done"
+
+echo ">>> Building sockpp... "
 pushd dependencies/sockpp-0.7.1/ >/dev/null 2>&1
 cmake -Bbuild .
 cmake --build build
 popd >/dev/null 2>&1
-echo "done."
 
+echo ">>> Cleaning up..."
 remove dependencies/tmp

scripts/test.sh

@@ -25,16 +25,20 @@ else
 fi
 echo "$LD_LIBRARY_PATH"
 
+echo ">>> Cleaning tests..."
+remove bin/test
 create_directory bin/test
 
-echo "Building tests..."
+echo ">>> Building tests..."
 
 # add compile commands to this array
 COMPILE_COMMANDS=(
-    "$CXX_WITH_FLAGS src/test/nbt_helpers.cpp -I./include -Lbin/lib -l:nbt.so -l:javacompat.so -o bin/test/nbt_helpers"
+    "$CXX_WITH_FLAGS src/test/nbt_read_write_helpers.cpp -I./include -Lbin/lib -l:nbt.so -l:javacompat.so -o bin/test/nbt_read_write_helpers"
     "$CXX_WITH_FLAGS src/test/cli_argument_parser.cpp -Lbin/lib -l:cli.so -o bin/test/cli_argument_parser"
     "$CXX_WITH_FLAGS src/test/javacompat.cpp -I./include -Lbin/lib -l:javacompat.so -o bin/test/javacompat"
-    "$CXX_WITH_FLAGS src/test/nbt_writestring_failure_mode.cpp -I./include -Lbin/lib -l:nbt.so -l:javacompat.so -o bin/test/nbt_writestring_failure_mode"
+    "$CXX_WITH_FLAGS src/test/nbt_write_string_failure_mode.cpp -I./include -Lbin/lib -l:nbt.so -l:javacompat.so -o bin/test/nbt_write_string_failure_mode"
+    "$CXX_WITH_FLAGS src/test/nbt_tags.cpp -I./include -Lbin/lib -l:nbt.so -l:javacompat.so -o bin/test/nbt_tags"
+    "$CXX_WITH_FLAGS src/test/nbt_size_helpers.cpp -I./include -Lbin/lib -l:nbt.so -l:javacompat.so -o bin/test/nbt_size_helpers"
 )
 for command in ${!COMPILE_COMMANDS[@]}; do
     echo "${COMPILE_COMMANDS[command]}"
@@ -44,9 +48,15 @@ done
 
 wait
 
-echo "Running tests..."
+echo ">>> Running tests..."
 
+# explicitly allow commands to fail at this stage
 set +e
+
 for test in $(ls bin/test); do
     bin/test/$test
 done
+
+for test in $(ls scripts/test); do
+    scripts/test/$test
+done

scripts/test/hexnet.sh

@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+
+# Copyright 2022, FOSS-VG Developers and Contributers
+#
+# This program is free software: you can redistribute it and/or modify it
+# under the terms of the GNU Affero General Public License as published
+# by the Free Software Foundation, version 3.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied
+# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+# See the GNU Affero General Public License for more details.
+#
+# You should have received a copy of the GNU Affero General Public License
+# version 3 along with this program.
+# If not, see https://www.gnu.org/licenses/agpl-3.0.en.html
+
+echo "################################################################################
+Testing hexnet
+################################################################################"
+
+echo "Test not yet implemented."
+#TODO: implement unit test after merging back with master

setupenv.bashrc

@@ -44,6 +44,4 @@ if [ -f "$PROJECT_BASE_DIR/.localenv.bashrc" ]; then
     source "$PROJECT_BASE_DIR/.localenv.bashrc"
 fi
 
-unset PROJECT_BASE_DIR
-
 echo "done."

src/lib/error.hpp

@@ -78,10 +78,12 @@ namespace ErrorCodes {
     // when dealing with maps
     const uint8_t UNKNOWN_KEY = 5;
 
+    //mismatched size in java strings
+    const uint8_t MISMATCHEDSIZE = 6;
+
+    const uint8_t NOT_YET_KNOWN = 7;
+
     const uint8_t UNIMPLEMENTED = 254;
 
     const uint8_t UNKNOWN = 255;
-
-    //mismatched size in java strings
-    const uint8_t MISMATCHEDSIZE = 6;
 }

src/lib/nbt.cpp

@@ -370,6 +370,151 @@ namespace NBT {
                 writeInt64(destination, data[i]);
             }
         }
+
+        //FIXME: instead of blindly passing the error code upwards, choose
+        // one that is applicable to the situation (for example replace
+        // OUT_OF_RANGE with OVERRUN where appropriate)
+        //
+        // The total size in bytes
+        //
+        // Does not work for compound tags and lists. This is an intended
+        // feature as compound tags and lists need to be dealt with
+        // separately to avoid unnecessarily long and complex code.
+        //
+        // Regardinng lists specifically: The size of some lists can can
+        // be determined easily by looking at the contained data type and
+        // size information but cases like string lists or compound lists
+        // are significantly more difficult to deal with. Parsing their
+        // contents requires special attention anyway due the tag headers
+        // of contained tags being absent so they may as well get their
+        // own function for this as well.
+        ErrorOr<uint64_t> totalTagSize(uint8_t data[], uint64_t dataSize, uint64_t currentPosition) {
+            uint8_t nextTag;
+            if (dataSize <= currentPosition) {
+                return ErrorOr<uint64_t>(true, ErrorCodes::OVERRUN);
+            } else {
+                nextTag = data[currentPosition];
+            }
+            // deal with compound tags and lists separately
+            if (nextTag == TagType::COMPOUND || nextTag == TagType::LIST) return ErrorOr<uint64_t>(true, ErrorCodes::NOT_YET_KNOWN);
+            // deal with end tag before trying to access the name
+            if (nextTag == TagType::END) return ErrorOr<uint64_t>(1);
+
+            ErrorOr<int16_t> nameSize = helper::readInt16(data, dataSize, currentPosition+1);
+            if (nameSize.isError) {
+                return ErrorOr<uint64_t>(true, nameSize.errorCode);
+            }
+            // add type byte and name size bytes
+            uint64_t prefixSize = (uint64_t) nameSize.value + 3;
+            switch (nextTag) {
+                case TagType::INT8:
+                    return ErrorOr<uint64_t>(prefixSize+1);
+                case TagType::INT16:
+                    return ErrorOr<uint64_t>(prefixSize+2);
+                case TagType::INT32:
+                    return ErrorOr<uint64_t>(prefixSize+4);
+                case TagType::INT64:
+                    return ErrorOr<uint64_t>(prefixSize+8);
+                case TagType::FLOAT:
+                    return ErrorOr<uint64_t>(prefixSize+4);
+                case TagType::DOUBLE:
+                    return ErrorOr<uint64_t>(prefixSize+8);
+                case TagType::INT8_ARRAY: {
+                    ErrorOr<int32_t> arrayLength = helper::readInt32(data, dataSize, currentPosition+prefixSize);
+                    if (arrayLength.isError) {
+                        return ErrorOr<uint64_t>(true, arrayLength.errorCode);
+                    }
+                    return ErrorOr<uint64_t>((uint64_t) arrayLength.value + prefixSize + 4);
+                }
+                case TagType::STRING: {
+                    ErrorOr<int16_t> stringSize = helper::readInt16(data, dataSize, currentPosition+prefixSize);
+                    if (stringSize.isError) {
+                        return ErrorOr<uint64_t>(true, stringSize.errorCode);
+                    }
+                    return ErrorOr<uint64_t>((uint64_t) stringSize.value + prefixSize + 2);
+                }
+                case TagType::INT32_ARRAY: {
+                    ErrorOr<int32_t> arrayLength = helper::readInt32(data, dataSize, currentPosition+prefixSize);
+                    if (arrayLength.isError) {
+                        return ErrorOr<uint64_t>(true, arrayLength.errorCode);
+                    }
+                    return ErrorOr<uint64_t>((uint64_t) arrayLength.value*4 + prefixSize + 4);
+                }
+                case TagType::INT64_ARRAY: {
+                    ErrorOr<int32_t> arrayLength = helper::readInt32(data, dataSize, currentPosition+prefixSize);
+                    if (arrayLength.isError) {
+                        return ErrorOr<uint64_t>(true, arrayLength.errorCode);
+                    }
+                    return ErrorOr<uint64_t>((uint64_t) arrayLength.value*8 + prefixSize + 4);
+                }
+                // unknown tag or parsing error
+                default:
+                    return ErrorOr<uint64_t>(true, ErrorCodes::UNKNOWN);
+            }
+        }
+
+        //FIXME: instead of blindly passing the error code upwards, choose
+        // one that is applicable to the situation (for example replace
+        // OUT_OF_RANGE with OVERRUN where appropriate)
+        //
+        // Length is the number of stored elements, not to be confused with size
+        // which is the size in bytes.
+        ErrorOr<int32_t> containedDataLength(uint8_t data[], uint64_t dataSize, uint64_t currentPosition){
+
+            uint8_t nextTag;
+            if (dataSize <= currentPosition) {
+                return ErrorOr<int32_t>(true, ErrorCodes::OVERRUN);
+            } else {
+                nextTag = data[currentPosition];
+            }
+
+            // deal with compound tags separately
+            if (nextTag == TagType::COMPOUND) {
+                return ErrorOr<int32_t>(true, ErrorCodes::NOT_YET_KNOWN);
+            }
+
+            // deal with end tag before trying to access the name
+            if (nextTag == TagType::END) {
+                return ErrorOr<int32_t>(0);
+            }
+
+            // tags that only ever hold one value
+            if (nextTag == TagType::INT8 || nextTag == TagType::INT16 || nextTag == TagType::INT32 || nextTag == TagType::INT64 || nextTag == TagType::FLOAT || nextTag == TagType::DOUBLE) {
+                return ErrorOr<int32_t>(1);
+            }
+
+            ErrorOr<int16_t> nameSize = helper::readInt16(data, dataSize, currentPosition+1);
+            if (nameSize.isError) {
+                return ErrorOr<int32_t>(true, nameSize.errorCode);
+            }
+            // add type byte and name size bytes
+            uint64_t prefixSize = (uint64_t) nameSize.value + 3;
+            switch (nextTag) {
+                case TagType::INT8_ARRAY: {
+                    return helper::readInt32(data, dataSize, currentPosition+prefixSize);
+                }
+                case TagType::STRING: {
+                    ErrorOr<int16_t> stringSize = helper::readInt16(data, dataSize, currentPosition+prefixSize);
+                    if (stringSize.isError) {
+                        return ErrorOr<int32_t>(true, stringSize.errorCode);
+                    }
+                    return ErrorOr<int32_t>((int32_t) stringSize.value);
+                }
+                case TagType::LIST: {
+                    // add an additional byte for the contained data type
+                    return helper::readInt32(data, dataSize, currentPosition+prefixSize+1);
+                }
+                case TagType::INT32_ARRAY: {
+                    return helper::readInt32(data, dataSize, currentPosition+prefixSize);
+                }
+                case TagType::INT64_ARRAY: {
+                    return helper::readInt32(data, dataSize, currentPosition+prefixSize);
+                }
+                default:
+                    // unknown tag or parsing error
+                    return ErrorOr<int32_t>(true, ErrorCodes::UNKNOWN);
+            }
+        }
     }
 
     //Tag constructors
@@ -424,9 +569,10 @@ namespace NBT {
         }
     }
 
-    bool validateRawNBTData(uint8_t data[], uint64_t dataSize){
-        //state machine?
-        //TODO: implement
+    bool validateRawNBTData(uint8_t data[], uint64_t dataSize, uint64_t initialPosition){
+        //TODO: find out the size of the next tag
+        //TODO: consume tag
+        //TODO: recurse if tag compound and return if tag end
         return false;
     }
 }

src/lib/nbt.hpp

@@ -66,6 +66,25 @@ namespace NBT {
         void writeInt32Array(std::vector<uint8_t>* destination, int32_t data[], uint32_t dataSize);
         void writeInt64Array(std::vector<uint8_t>* destination, std::vector<int64_t> data);
         void writeInt64Array(std::vector<uint8_t>* destination, int64_t data[], uint32_t dataSize);
+
+        ErrorOr<uint64_t> totalTagSize(uint8_t data[], uint64_t dataSize, uint64_t currentPosition);
+        ErrorOr<int32_t> containedDataLength(uint8_t data[], uint64_t dataSize, uint64_t currentPosition);
+    }
+
+    namespace TagType {
+        const uint8_t END        =  0;
+        const uint8_t INT8       =  1;
+        const uint8_t INT16      =  2;
+        const uint8_t INT32      =  3;
+        const uint8_t INT64      =  4;
+        const uint8_t FLOAT      =  5;
+        const uint8_t DOUBLE     =  6;
+        const uint8_t INT8_ARRAY =  7;
+        const uint8_t STRING     =  8;
+        const uint8_t LIST       =  9;
+        const uint8_t COMPOUND   = 10;
+        const uint8_t INT32_ARRAY= 11;
+        const uint8_t INT64_ARRAY= 12;
     }
 
     //Generic parent class to make declaration easier
@@ -94,5 +113,5 @@ namespace NBT {
         bool validate(uint8_t data[]);
     };
 
-    bool validateRawNBTData(uint8_t data[], int length);
+    bool validateRawNBTData(uint8_t data[], int length, uint64_t initialPosition=0);
 }

src/test/assert.hpp

@@ -15,4 +15,4 @@
 
 #include <iostream>
 
-#define ASSERT(truth) if ((truth)); else { std::cout << "Assertion failed: " << #truth << std::endl; return 1; }
+#define ASSERT(truth) if ((truth)); else { std::cout << "On line " << __LINE__ << ": Assertion failed: " << #truth << std::endl; return 1; }

src/test/nbt_read_write_helpers.cpp

@@ -26,7 +26,7 @@
 
 int main(){
     std::cout << "################################################################################" << std::endl;
-    std::cout << "NBT helper tests" << std::endl;
+    std::cout << "NBT read/write helper tests" << std::endl;
     std::cout << "################################################################################" << std::endl;
 
     // used for all integer tests
@@ -524,15 +524,5 @@ int main(){
 
     std::cout << "Passed writeString NBT helper test." << std::endl;
 
-    //Byte tag constructor test
-    uint8_t bytetest[] = {0x01, 0x00, 0x02, 0x68, 0x69, 0x32};
-    NBT::Byte byte = NBT::Byte(bytetest);
-
-    ASSERT(byte.tagType == 1);
-    ASSERT(byte.nameSize == 2);
-    ASSERT(byte.content = 0x32);
-    ASSERT(byte.name == tiny_utf8::string("hi"));
-
-    std::cout << "Passed Byte Tag constructor test." << std::endl;
     return 0;
 }

src/test/nbt_size_helpers.cpp

@@ -0,0 +1,257 @@
+// Copyright 2022, FOSS-VG Developers and Contributers
+//
+// This program is free software: you can redistribute it and/or modify it
+// under the terms of the GNU Affero General Public License as published
+// by the Free Software Foundation, version 3.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied
+// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+// See the GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// version 3 along with this program.
+// If not, see https://www.gnu.org/licenses/agpl-3.0.en.html
+
+#include <iostream>
+#include <cstdint>
+
+#include "assert.hpp"
+
+#include "../lib/nbt.hpp"
+#include "../lib/error.hpp"
+
+int main() {
+    std::cout
+        << "################################################################################\n"
+        << "NBT size helper tests\n"
+        << "################################################################################"
+        << std::endl;
+
+    // a full copy of /resources/NBT_data/simple_nbt
+    //
+    // This contains all tag types. It is most likely not suitable for
+    // tests chasing edge cases as it is - as the name says - really
+    // basic NBT data.
+    uint8_t simpleNBTData[] = {
+        0x0a, 0x00, 0x00, 0x08, 0x00, 0x3e, 0x53, 0x70,
+        0x61, 0x63, 0x65, 0x73, 0x20, 0x61, 0x6e, 0x64,
+        0x20, 0x73, 0x70, 0x65, 0x63, 0x69, 0x61, 0x6c,
+        0x20, 0x63, 0x68, 0x61, 0x72, 0x61, 0x63, 0x74,
+        0x65, 0x72, 0x73, 0x20, 0x61, 0x72, 0x65, 0x20,
+        0x61, 0x6c, 0x6c, 0x6f, 0x77, 0x65, 0x64, 0x20,
+        0x69, 0x6e, 0x20, 0x74, 0x61, 0x67, 0x20, 0x6e,
+        0x61, 0x6d, 0x65, 0x73, 0x2c, 0x20, 0x72, 0x69,
+        0x67, 0x68, 0x74, 0x3f, 0x00, 0x16, 0x49, 0x64,
+        0x6b, 0x2e, 0x20, 0x4c, 0x65, 0x74, 0xe2, 0x80,
+        0x99, 0x73, 0x20, 0x66, 0x69, 0x6e, 0x64, 0x20,
+        0x6f, 0x75, 0x74, 0x2e, 0x0a, 0x00, 0x08, 0x63,
+        0x6f, 0x6d, 0x70, 0x6f, 0x75, 0x6e, 0x64, 0x03,
+        0x00, 0x0b, 0x73, 0x6f, 0x6d, 0x65, 0x5f, 0x6e,
+        0x75, 0x6d, 0x62, 0x65, 0x72, 0xd3, 0x07, 0x23,
+        0x41, 0x08, 0x00, 0x09, 0x73, 0x6f, 0x6d, 0x65,
+        0x5f, 0x74, 0x65, 0x78, 0x74, 0x00, 0x0c, 0x65,
+        0x61, 0x74, 0x20, 0x61, 0x20, 0x63, 0x6f, 0x6f,
+        0x6b, 0x69, 0x65, 0x00, 0x06, 0x00, 0x06, 0x64,
+        0x6f, 0x75, 0x62, 0x6c, 0x65, 0x41, 0x23, 0x07,
+        0xd3, 0x4e, 0xfd, 0x07, 0xf1, 0x05, 0x00, 0x05,
+        0x66, 0x6c, 0x6f, 0x61, 0x74, 0x42, 0x0d, 0x12,
+        0x43, 0x02, 0x00, 0x05, 0x69, 0x6e, 0x74, 0x31,
+        0x36, 0x07, 0xd0, 0x03, 0x00, 0x05, 0x69, 0x6e,
+        0x74, 0x33, 0x32, 0x00, 0x9a, 0x21, 0x12, 0x0b,
+        0x00, 0x0b, 0x69, 0x6e, 0x74, 0x33, 0x32, 0x5f,
+        0x61, 0x72, 0x72, 0x61, 0x79, 0x00, 0x00, 0x00,
+        0x04, 0x17, 0xbf, 0xe8, 0x3c, 0x00, 0x00, 0xa8,
+        0xfb, 0x7f, 0xff, 0xff, 0xff, 0x61, 0x72, 0x72,
+        0x61, 0x04, 0x00, 0x05, 0x69, 0x6e, 0x74, 0x36,
+        0x34, 0x00, 0x00, 0x00, 0xbc, 0x97, 0xde, 0x9e,
+        0x3e, 0x0c, 0x00, 0x0b, 0x69, 0x6e, 0x74, 0x36,
+        0x34, 0x5f, 0x61, 0x72, 0x72, 0x61, 0x79, 0x00,
+        0x00, 0x00, 0x05, 0x00, 0x00, 0x00, 0x00, 0x00,
+        0x03, 0xa8, 0xf9, 0x00, 0x00, 0x00, 0x00, 0x01,
+        0x67, 0xe7, 0xbd, 0x7f, 0xff, 0xff, 0xff, 0xff,
+        0xff, 0xff, 0xff, 0x00, 0x00, 0xab, 0xd8, 0x00,
+        0x00, 0xab, 0xd8, 0x00, 0x0b, 0x12, 0x21, 0x00,
+        0x79, 0x61, 0x72, 0x01, 0x00, 0x04, 0x69, 0x6e,
+        0x74, 0x38, 0x64, 0x07, 0x00, 0x0a, 0x69, 0x6e,
+        0x74, 0x38, 0x5f, 0x61, 0x72, 0x72, 0x61, 0x79,
+        0x00, 0x00, 0x00, 0x08, 0x71, 0x35, 0x77, 0x62,
+        0x54, 0x64, 0xf5, 0x32, 0x09, 0x00, 0x09, 0x6c,
+        0x69, 0x73, 0x74, 0x5f, 0x69, 0x6e, 0x74, 0x38,
+        0x01, 0x00, 0x00, 0x00, 0x05, 0x41, 0x60, 0x4e,
+        0x7f, 0xfa, 0x09, 0x00, 0x0c, 0x6c, 0x69, 0x73,
+        0x74, 0x5f, 0x73, 0x74, 0x72, 0x69, 0x6e, 0x67,
+        0x73, 0x08, 0x00, 0x00, 0x00, 0x0c, 0x00, 0x06,
+        0x50, 0x61, 0x63, 0x6d, 0x61, 0x6e, 0x00, 0x03,
+        0x61, 0x74, 0x65, 0x00, 0x03, 0x61, 0x6c, 0x6c,
+        0x00, 0x03, 0x74, 0x68, 0x65, 0x00, 0x04, 0x64,
+        0x6f, 0x74, 0x73, 0x00, 0x02, 0x73, 0x6f, 0x00,
+        0x03, 0x6e, 0x6f, 0x77, 0x00, 0x06, 0x68, 0x65,
+        0xe2, 0x80, 0x99, 0x73, 0x00, 0x06, 0x63, 0x6f,
+        0x6d, 0x69, 0x6e, 0x67, 0x00, 0x03, 0x66, 0x6f,
+        0x72, 0x00, 0x03, 0x74, 0x68, 0x65, 0x00, 0x06,
+        0x77, 0x6f, 0x72, 0x64, 0x73, 0x2e, 0x08, 0x00,
+        0x06, 0x73, 0x74, 0x72, 0x69, 0x6e, 0x67, 0x00,
+        0x0c, 0x48, 0x65, 0x6c, 0x6c, 0x6f, 0x20, 0x57,
+        0x6f, 0x72, 0x6c, 0x64, 0x21, 0x00
+    };
+    uint64_t simpleNBTDataSize = 478;
+
+    //##################################################################
+    // Basic valid data tests
+    //##################################################################
+    // const uint8_t END        =  0;
+    ErrorOr<uint64_t> totalSize = NBT::helper::totalTagSize(simpleNBTData, simpleNBTDataSize, 0x93);
+    ErrorOr<int32_t> dataLength = NBT::helper::containedDataLength(simpleNBTData, simpleNBTDataSize, 0x93);
+
+    ASSERT(!totalSize.isError);
+    ASSERT(totalSize.value == 1);
+    ASSERT(!dataLength.isError);
+    ASSERT(dataLength.value == 0);
+
+    totalSize = NBT::helper::totalTagSize(simpleNBTData, simpleNBTDataSize, 477);
+    dataLength = NBT::helper::containedDataLength(simpleNBTData, simpleNBTDataSize, 477);
+
+    ASSERT(!totalSize.isError);
+    ASSERT(totalSize.value == 1);
+    ASSERT(!dataLength.isError);
+    ASSERT(dataLength.value == 0);
+
+    //const uint8_t INT8       =  1;
+    totalSize = NBT::helper::totalTagSize(simpleNBTData, simpleNBTDataSize, 0x133);
+    dataLength = NBT::helper::containedDataLength(simpleNBTData, simpleNBTDataSize, 0x133);
+
+    ASSERT(!totalSize.isError);
+    ASSERT(totalSize.value == 8);
+    ASSERT(!dataLength.isError);
+    ASSERT(dataLength.value == 1);
+
+    //const uint8_t INT16      =  2;
+    totalSize = NBT::helper::totalTagSize(simpleNBTData, simpleNBTDataSize, 0xb1);
+    dataLength = NBT::helper::containedDataLength(simpleNBTData, simpleNBTDataSize, 0xb1);
+
+    ASSERT(!totalSize.isError);
+    ASSERT(totalSize.value == 10);
+    ASSERT(!dataLength.isError);
+    ASSERT(dataLength.value == 1);
+
+    //const uint8_t INT32      =  3;
+    totalSize = NBT::helper::totalTagSize(simpleNBTData, simpleNBTDataSize, 0xbb);
+    dataLength = NBT::helper::containedDataLength(simpleNBTData, simpleNBTDataSize, 0xbb);
+
+    ASSERT(!totalSize.isError);
+    ASSERT(totalSize.value == 12);
+    ASSERT(!dataLength.isError);
+    ASSERT(dataLength.value == 1);
+
+    totalSize = NBT::helper::totalTagSize(simpleNBTData, simpleNBTDataSize, 0x67);
+    dataLength = NBT::helper::containedDataLength(simpleNBTData, simpleNBTDataSize, 0x67);
+
+    ASSERT(!totalSize.isError);
+    ASSERT(totalSize.value == 18);
+    ASSERT(!dataLength.isError);
+    ASSERT(dataLength.value == 1);
+
+    //const uint8_t INT64      =  4;
+    totalSize = NBT::helper::totalTagSize(simpleNBTData, simpleNBTDataSize, 0xe9);
+    dataLength = NBT::helper::containedDataLength(simpleNBTData, simpleNBTDataSize, 0xe9);
+
+    ASSERT(!totalSize.isError);
+    ASSERT(totalSize.value == 16);
+    ASSERT(!dataLength.isError);
+    ASSERT(dataLength.value == 1);
+
+    //const uint8_t FLOAT      =  5;
+    totalSize = NBT::helper::totalTagSize(simpleNBTData, simpleNBTDataSize, 0xa5);
+    dataLength = NBT::helper::containedDataLength(simpleNBTData, simpleNBTDataSize, 0xa5);
+
+    ASSERT(!totalSize.isError);
+    ASSERT(totalSize.value == 12);
+    ASSERT(!dataLength.isError);
+    ASSERT(dataLength.value == 1);
+
+    //const uint8_t DOUBLE     =  6;
+    totalSize = NBT::helper::totalTagSize(simpleNBTData, simpleNBTDataSize, 0x94);
+    dataLength = NBT::helper::containedDataLength(simpleNBTData, simpleNBTDataSize, 0x94);
+
+    ASSERT(!totalSize.isError);
+    ASSERT(totalSize.value == 17);
+    ASSERT(!dataLength.isError);
+    ASSERT(dataLength.value == 1);
+
+    //const uint8_t INT8_ARRAY =  7;
+    totalSize = NBT::helper::totalTagSize(simpleNBTData, simpleNBTDataSize, 0x13b);
+    dataLength = NBT::helper::containedDataLength(simpleNBTData, simpleNBTDataSize, 0x13b);
+
+    ASSERT(!totalSize.isError);
+    ASSERT(totalSize.value == 25);
+    ASSERT(!dataLength.isError);
+    ASSERT(dataLength.value == 8);
+
+    //const uint8_t STRING     =  8;
+    totalSize = NBT::helper::totalTagSize(simpleNBTData, simpleNBTDataSize, 0x1c6);
+    dataLength = NBT::helper::containedDataLength(simpleNBTData, simpleNBTDataSize, 0x1c6);
+
+    ASSERT(!totalSize.isError);
+    ASSERT(totalSize.value == 23);
+    ASSERT(!dataLength.isError);
+    ASSERT(dataLength.value == 12);
+
+    totalSize = NBT::helper::totalTagSize(simpleNBTData, simpleNBTDataSize, 0x79);
+    dataLength = NBT::helper::containedDataLength(simpleNBTData, simpleNBTDataSize, 0x79);
+
+    ASSERT(!totalSize.isError);
+    ASSERT(totalSize.value == 26);
+    ASSERT(!dataLength.isError);
+    ASSERT(dataLength.value == 12);
+
+    //const uint8_t LIST       =  9;
+    totalSize = NBT::helper::totalTagSize(simpleNBTData, simpleNBTDataSize, 0x154);
+    dataLength = NBT::helper::containedDataLength(simpleNBTData, simpleNBTDataSize, 0x154);
+
+    ASSERT(totalSize.isError);
+    ASSERT(totalSize.errorCode == ErrorCodes::NOT_YET_KNOWN);
+    ASSERT(!dataLength.isError);
+    ASSERT(dataLength.value == 5);
+
+    totalSize = NBT::helper::totalTagSize(simpleNBTData, simpleNBTDataSize, 0x16a);
+    dataLength = NBT::helper::containedDataLength(simpleNBTData, simpleNBTDataSize, 0x16a);
+
+    ASSERT(totalSize.isError);
+    ASSERT(totalSize.errorCode == ErrorCodes::NOT_YET_KNOWN);
+    ASSERT(!dataLength.isError);
+    ASSERT(dataLength.value == 12);
+
+    //const uint8_t COMPOUND   = 10;
+    totalSize = NBT::helper::totalTagSize(simpleNBTData, simpleNBTDataSize, 0x5c);
+    dataLength = NBT::helper::containedDataLength(simpleNBTData, simpleNBTDataSize, 0x5c);
+
+    ASSERT(totalSize.isError);
+    ASSERT(totalSize.errorCode == ErrorCodes::NOT_YET_KNOWN);
+    ASSERT(dataLength.isError);
+    ASSERT(dataLength.errorCode == ErrorCodes::NOT_YET_KNOWN);
+
+    //const uint8_t INT32_ARRAY= 11;
+    totalSize = NBT::helper::totalTagSize(simpleNBTData, simpleNBTDataSize, 0xc7);
+    dataLength = NBT::helper::containedDataLength(simpleNBTData, simpleNBTDataSize, 0xc7);
+
+    ASSERT(!totalSize.isError);
+    ASSERT(totalSize.value == 34);
+    ASSERT(!dataLength.isError);
+    ASSERT(dataLength.value == 4);
+
+    //const uint8_t INT64_ARRAY= 12;
+    totalSize = NBT::helper::totalTagSize(simpleNBTData, simpleNBTDataSize, 0xf9);
+    dataLength = NBT::helper::containedDataLength(simpleNBTData, simpleNBTDataSize, 0xf9);
+
+    ASSERT(!totalSize.isError);
+    ASSERT(totalSize.value == 58);
+    ASSERT(!dataLength.isError);
+    ASSERT(dataLength.value == 5);
+
+    std::cout << "Passed simple valid data test." << std::endl;
+
+    //TODO: add tests for errors and edge cases
+
+    return 0;
+}

src/test/nbt_tags.cpp

@@ -0,0 +1,44 @@
+// Copyright 2022, FOSS-VG Developers and Contributers
+//
+// This program is free software: you can redistribute it and/or modify it
+// under the terms of the GNU Affero General Public License as published
+// by the Free Software Foundation, version 3.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied
+// warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+// See the GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// version 3 along with this program.
+// If not, see https://www.gnu.org/licenses/agpl-3.0.en.html
+
+#include <iostream>
+#include <cstdint>
+#include <vector>
+#include <fstream>
+
+#include "assert.hpp"
+
+#include "../lib/nbt.hpp"
+#include "../lib/error.hpp"
+#include "../lib/javacompat.hpp"
+
+int main(){
+    std::cout << "################################################################################" << std::endl;
+    std::cout << "NBT object tests" << std::endl;
+    std::cout << "################################################################################" << std::endl;
+
+    //Byte tag constructor test
+    uint8_t bytetest[] = {0x01, 0x00, 0x02, 0x68, 0x69, 0x32};
+    NBT::Byte byte = NBT::Byte(bytetest);
+
+    ASSERT(byte.tagType == 1);
+    ASSERT(byte.nameSize == 2);
+    ASSERT(byte.content = 0x32);
+    ASSERT(byte.name == tiny_utf8::string("hi"));
+
+    std::cout << "Passed Byte Tag constructor test." << std::endl;
+
+    return 0;
+}