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#include <vector>
#include <stdexcept>
#include <cstdint>
#include <cstring>
#include <string>
#include <utility>
#include <zlib.h>
#include "bk_unzip.h"
#include "spdlog/spdlog.h"
namespace BK64 {
static const char* zlibResultName(int result) {
switch (result) {
case Z_OK:
return "Z_OK";
case Z_STREAM_END:
return "Z_STREAM_END";
case Z_NEED_DICT:
return "Z_NEED_DICT";
case Z_ERRNO:
return "Z_ERRNO";
case Z_STREAM_ERROR:
return "Z_STREAM_ERROR";
case Z_DATA_ERROR:
return "Z_DATA_ERROR";
case Z_MEM_ERROR:
return "Z_MEM_ERROR";
case Z_BUF_ERROR:
return "Z_BUF_ERROR";
case Z_VERSION_ERROR:
return "Z_VERSION_ERROR";
default:
return "UNKNOWN";
}
}
/**
* Implementation of bk_unzip as declared in bk_unzip.h
*/
uint8_t* bk_unzip(const uint8_t* in_buffer, uint32_t* size) {
// Check buffer size
if (*size < 6) {
throw std::runtime_error("Input buffer too small");
}
// Check for BK magic header
if (in_buffer[0] != 0x11 || in_buffer[1] != 0x72) {
throw std::runtime_error("Input buffer does not have BK header");
}
// Extract expected uncompressed length (big-endian)
uint32_t expected_len = (static_cast<uint32_t>(in_buffer[2]) << 24) | (static_cast<uint32_t>(in_buffer[3]) << 16) |
(static_cast<uint32_t>(in_buffer[4]) << 8) | static_cast<uint32_t>(in_buffer[5]);
if (expected_len == 0) {
*size = 0;
return (uint8_t*)malloc(1);
}
if (expected_len > 8 * 1024 * 1024) {
throw std::runtime_error("BKZIP expected size too large: " + std::to_string(expected_len) +
" bytes (compressed: " + std::to_string(*size) + ")");
}
uint8_t* out_buffer = (uint8_t*)malloc(expected_len);
memset(out_buffer, 0, expected_len);
// Set up zlib stream
z_stream stream;
stream.zalloc = Z_NULL;
stream.zfree = Z_NULL;
stream.opaque = Z_NULL;
stream.avail_in = static_cast<uInt>(*size - 6);
stream.next_in = const_cast<Bytef*>(in_buffer + 6);
stream.avail_out = static_cast<uInt>(expected_len);
stream.next_out = out_buffer;
// Initialize for raw inflate (no zlib/gzip header) - same as wbits=-15 in Python
int result = inflateInit2(&stream, -15);
if (result != Z_OK) {
throw std::runtime_error(std::string("Failed to initialize zlib: ") + zlibResultName(result) +
(stream.msg ? std::string(" (") + stream.msg + ")" : ""));
}
// Perform decompression
result = inflate(&stream, Z_FINISH);
// Check for successful decompression:
// - Z_STREAM_END: normal completion
// - Z_BUF_ERROR with no input remaining: input fully consumed
// - Z_BUF_ERROR with output complete: all expected bytes produced (BB-extended ROMs
// may have compressed sizes that include trailing padding from adjacent assets)
bool success = (result == Z_STREAM_END) || (result == Z_BUF_ERROR && stream.avail_in == 0) ||
(result == Z_BUF_ERROR && stream.total_out == expected_len);
// Clean up zlib stream
inflateEnd(&stream);
if (!success) {
free(out_buffer);
throw std::runtime_error(std::string("Decompression failed: ") + zlibResultName(result) +
(stream.msg ? std::string(" (") + stream.msg + ")" : "") +
" compressed=" + std::to_string(*size) + " expected=" + std::to_string(expected_len) +
" produced=" + std::to_string(stream.total_out));
}
// Resize buffer to the actual decompressed size
// out_buffer.resize(stream.total_out);
*size = stream.total_out;
// Verify decompressed size matches expected size
if (stream.total_out != expected_len) {
throw std::runtime_error("Decompressed size (" + std::to_string(stream.total_out) +
") does not match expected size (" + std::to_string(expected_len) + ")");
}
return out_buffer;
}
} // namespace BK64
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