From 7649e5d58fc1ecef42d77e68ea2b482cff48d5b7 Mon Sep 17 00:00:00 2001
From: Jan <jan@laupetin.net>
Date: Sun, 22 Sep 2024 15:10:54 +0200
Subject: [PATCH] chore: generalize base64 usage

---
 src/Crypto/Impl/Base64.cpp                    | 49 +++++++++++++++++++
 src/Crypto/Impl/Base64.h                      | 12 +++++
 .../XModel/Gltf/Internal/GltfBuffer.cpp       | 15 ++----
 src/ObjWriting/XModel/Gltf/GltfTextOutput.cpp | 11 ++---
 4 files changed, 71 insertions(+), 16 deletions(-)
 create mode 100644 src/Crypto/Impl/Base64.cpp
 create mode 100644 src/Crypto/Impl/Base64.h

diff --git a/src/Crypto/Impl/Base64.cpp b/src/Crypto/Impl/Base64.cpp
new file mode 100644
index 00000000..f4400d6a
--- /dev/null
+++ b/src/Crypto/Impl/Base64.cpp
@@ -0,0 +1,49 @@
+#include "Base64.h"
+
+#define LTC_NO_PROTOTYPES
+#include <tomcrypt.h>
+
+namespace base64
+{
+    std::string EncodeBase64(const void* inputData, const size_t inputLength)
+    {
+        const auto base64BufferSize = GetBase64EncodeOutputLength(inputLength);
+
+        std::string output(base64BufferSize, '\0');
+        const auto outLength = base64BufferSize + 1u;
+
+        const auto result = EncodeBase64(inputData, inputLength, output.data(), outLength);
+        assert(result);
+
+        return output;
+    }
+
+    bool EncodeBase64(const void* inputData, const size_t inputLength, void* outputBuffer, const size_t outputBufferSize)
+    {
+        unsigned long outLength = outputBufferSize;
+        const auto result = base64_encode(static_cast<const unsigned char*>(inputData), inputLength, static_cast<char*>(outputBuffer), &outLength);
+        return result == CRYPT_OK;
+    }
+
+    size_t GetBase64EncodeOutputLength(const size_t inputLength)
+    {
+        return 4u * ((inputLength + 2u) / 3u);
+    }
+
+    size_t DecodeBase64(const void* base64Data, const size_t inputLength, void* outputBuffer, const size_t outputBufferSize)
+    {
+        unsigned long outLength = GetBase64DecodeOutputLength(inputLength);
+        if (outLength > outputBufferSize)
+            return 0u;
+
+        const auto result = base64_decode(static_cast<const char*>(base64Data), inputLength, static_cast<unsigned char*>(outputBuffer), &outLength);
+        assert(result == CRYPT_OK);
+
+        return static_cast<size_t>(outLength);
+    }
+
+    size_t GetBase64DecodeOutputLength(const size_t inputLength)
+    {
+        return inputLength / 4u;
+    }
+} // namespace base64
diff --git a/src/Crypto/Impl/Base64.h b/src/Crypto/Impl/Base64.h
new file mode 100644
index 00000000..1e1ec51d
--- /dev/null
+++ b/src/Crypto/Impl/Base64.h
@@ -0,0 +1,12 @@
+#pragma once
+#include <string>
+
+namespace base64
+{
+    std::string EncodeBase64(const void* inputData, size_t inputLength);
+    bool EncodeBase64(const void* inputData, size_t inputLength, void* outputBuffer, size_t outputBufferSize);
+    size_t GetBase64EncodeOutputLength(size_t inputLength);
+
+    size_t DecodeBase64(const void* base64Data, size_t inputLength, void* outputBuffer, size_t outputBufferSize);
+    size_t GetBase64DecodeOutputLength(size_t inputLength);
+} // namespace base64
diff --git a/src/ObjLoading/XModel/Gltf/Internal/GltfBuffer.cpp b/src/ObjLoading/XModel/Gltf/Internal/GltfBuffer.cpp
index 95ec99a1..a0edf7f0 100644
--- a/src/ObjLoading/XModel/Gltf/Internal/GltfBuffer.cpp
+++ b/src/ObjLoading/XModel/Gltf/Internal/GltfBuffer.cpp
@@ -1,14 +1,12 @@
 #include "GltfBuffer.h"
 
+#include "Impl/Base64.h"
 #include "XModel/Gltf/GltfConstants.h"
 
 #include <cassert>
 #include <cstdint>
 #include <cstring>
 
-#define LTC_NO_PROTOTYPES
-#include <tomcrypt.h>
-
 using namespace gltf;
 
 EmbeddedBuffer::EmbeddedBuffer(const void* data, const size_t dataSize)
@@ -51,15 +49,12 @@ bool DataUriBuffer::ReadDataFromUri(const std::string& uri)
         return false;
 
     const auto base64DataLength = uri.size() - URI_PREFIX_LENGTH;
+    m_data_size = base64::GetBase64DecodeOutputLength(base64DataLength);
+    m_data = std::make_unique<uint8_t[]>(m_data_size);
 
-    unsigned long outLength = base64DataLength / 4u;
-    m_data = std::make_unique<uint8_t[]>(outLength);
-    const auto result = base64_decode(&uri[URI_PREFIX_LENGTH], base64DataLength, m_data.get(), &outLength);
-    m_data_size = static_cast<size_t>(outLength);
+    m_data_size = base64::DecodeBase64(&uri[URI_PREFIX_LENGTH], base64DataLength, m_data.get(), m_data_size);
 
-    assert(result == CRYPT_OK);
-
-    return false;
+    return m_data_size > 0;
 }
 
 bool DataUriBuffer::ReadData(void* dest, const size_t offset, const size_t count) const
diff --git a/src/ObjWriting/XModel/Gltf/GltfTextOutput.cpp b/src/ObjWriting/XModel/Gltf/GltfTextOutput.cpp
index effb524a..49afebd6 100644
--- a/src/ObjWriting/XModel/Gltf/GltfTextOutput.cpp
+++ b/src/ObjWriting/XModel/Gltf/GltfTextOutput.cpp
@@ -6,6 +6,8 @@
 #include <nlohmann/json.hpp>
 
 #define LTC_NO_PROTOTYPES
+#include "Impl/Base64.h"
+
 #include <tomcrypt.h>
 
 using namespace gltf;
@@ -17,18 +19,15 @@ TextOutput::TextOutput(std::ostream& stream)
 
 std::optional<std::string> TextOutput::CreateBufferUri(const void* buffer, const size_t bufferSize) const
 {
-    const auto base64Length = 4u * ((bufferSize + 2u) / 3u);
+    const auto base64Length = base64::GetBase64EncodeOutputLength(bufferSize);
     const auto base64BufferSize = URI_PREFIX_LENGTH + base64Length;
 
     std::string output(base64BufferSize, '\0');
 
     std::memcpy(output.data(), GLTF_DATA_URI_PREFIX, URI_PREFIX_LENGTH);
 
-    unsigned long outLength = base64Length + 1u;
-    const auto result = base64_encode(static_cast<const unsigned char*>(buffer), bufferSize, &output[URI_PREFIX_LENGTH], &outLength);
-
-    assert(result == CRYPT_OK);
-    assert(outLength == base64Length);
+    auto result = base64::EncodeBase64(buffer, bufferSize, &output[URI_PREFIX_LENGTH], base64Length + 1u);
+    assert(result);
 
     return output;
 }