feat(util): add ZlibDecompress

src/util/CMakeLists.txt

@@ -28,6 +28,8 @@ target_link_libraries(util
         common
         storm
         tempest
+    PRIVATE
+        zlib-1.2
 )
 
 if(WHOA_SYSTEM_LINUX OR WHOA_SYSTEM_MAC)

src/util/Zlib.cpp

@@ -0,0 +1,76 @@
+#include "util/Zlib.hpp"
+#include <storm/Error.hpp>
+#include <storm/Memory.hpp>
+#include <zlib.h>
+
+int zlib_uncompress(Bytef* dest, uInt* destLen, const Bytef* source, uInt sourceLen) {
+    char buffer[47000];
+    ZlibAllocBufferHeader header = { buffer, sizeof(buffer), buffer };
+
+    z_stream strm;
+    strm.next_in = const_cast<Bytef*>(source);
+    strm.avail_in = sourceLen;
+    strm.next_out = dest;
+    strm.avail_out = *destLen;
+    strm.zalloc = &ZlibAlloc;
+    strm.zfree = &ZlibFree;
+    strm.opaque = &header;
+
+    auto err = inflateInit(&strm);
+    if (err != Z_OK) {
+        return err;
+    }
+
+    err = inflate(&strm, Z_FINISH);
+    if (err == Z_STREAM_END) {
+        *destLen = strm.total_out;
+        return inflateEnd(&strm);
+    }
+
+    inflateEnd(&strm);
+    return err ? err : Z_BUF_ERROR;
+}
+
+void* ZlibAlloc(void* opaque, uint32_t items, uint32_t size) {
+    auto buffer = static_cast<ZlibAllocBufferHeader*>(opaque);
+    STORM_ASSERT(buffer);
+
+    uint32_t total = items * size;
+
+    // Align to 4 bytes
+    if ((total & 3) != 0) {
+        total = (total & ~3) + 4;
+    }
+
+    auto ptr = buffer->nextPtr;
+    size_t used = buffer->nextPtr - buffer->bufStart;
+    size_t remaining = buffer->bufSize - used;
+
+    // Fall back to heap if stack allocated buffer is exhausted
+    if (total >= remaining) {
+        return STORM_ALLOC(total);
+    }
+
+    buffer->nextPtr = ptr + total;
+    return ptr;
+}
+
+void ZlibFree(void* opaque, void* ptr) {
+    auto* buffer = static_cast<ZlibAllocBufferHeader*>(opaque);
+    auto bufferStart = buffer->bufStart;
+    auto bufferEnd = buffer->bufStart + buffer->bufSize;
+
+    // Only free if pointer is outside of stack allocated buffer
+    if (ptr < bufferStart || ptr >= bufferEnd) {
+        STORM_FREE(ptr);
+    }
+}
+
+int32_t ZlibDecompress(void* dest, uint32_t* destLen, const void* source, uint32_t sourceLen) {
+    return zlib_uncompress(
+        static_cast<Bytef*>(dest),
+        destLen,
+        static_cast<const Bytef*>(source),
+        sourceLen
+    );
+}

src/util/Zlib.hpp

@@ -0,0 +1,18 @@
+#ifndef UTIL_ZLIB_HPP
+#define UTIL_ZLIB_HPP
+
+#include <cstdint>
+
+struct ZlibAllocBufferHeader {
+    char* nextPtr;
+    uint32_t bufSize;
+    char* bufStart;
+};
+
+void* ZlibAlloc(void* opaque, uint32_t items, uint32_t size);
+
+int32_t ZlibDecompress(void* dest, uint32_t* destLen, const void* source, uint32_t sourceLen);
+
+void ZlibFree(void* opaque, void* ptr);
+
+#endif