add extract assets tool

tools/extract/extract.cpp

@@ -0,0 +1,72 @@
+#include <iostream>
+#include <fstream>
+#include <vector>
+#include <cstdint>
+
+const uint32_t PNG_SIGNATURE = 0x89504E47;
+const uint32_t PNG_END_SIGNATURE = 0xAE426082;
+
+bool readFileToBuffer(const std::string& filename, std::vector<uint8_t>& buffer) {
+    std::ifstream file(filename, std::ios::binary);
+    if (!file) {
+        std::cerr << "Unable to open file: " << filename << std::endl;
+        return false;
+    }
+
+    // Read the entire file into a buffer
+    buffer.assign((std::istreambuf_iterator<char>(file)), std::istreambuf_iterator<char>());
+    return true;
+}
+
+void extractPNGs(const std::string& outdir, const std::vector<uint8_t>& buffer) {
+    size_t offset = 0;
+    size_t fileCount = 0;
+
+    while (offset < buffer.size() - 8) { // Ensure there's enough data for the end signature
+        // Look for the PNG signature
+        if (buffer[offset] == 0x89 && buffer[offset + 1] == 0x50 && 
+            buffer[offset + 2] == 0x4E && buffer[offset + 3] == 0x47) {
+            
+            // Check for the end signature starting from the PNG signature position
+            size_t endOffset = offset;
+            while (endOffset <= buffer.size() - 4) {
+                if (buffer[endOffset] == 0xAE && buffer[endOffset + 1] == 0x42 &&
+                    buffer[endOffset + 2] == 0x60 && buffer[endOffset + 3] == 0x82) {
+                    
+                    // We found the end signature; extract the PNG
+                    std::string outputFilename = std::to_string(fileCount++) + ".png";
+                    std::ofstream outFile(outdir + outputFilename, std::ios::binary);
+                    if (outFile) {
+                        outFile.write(reinterpret_cast<const char*>(&buffer[offset]), endOffset - offset + 4); // Include end signature
+                        std::cout << "Extracted: " << outputFilename << std::endl;
+                    } else {
+                        std::cerr << "Unable to create file: " << outputFilename << std::endl;
+                    }
+
+                    // Move offset to end of current PNG
+                    offset = endOffset + 4; // Move past the end signature
+                    break; // Break to search for the next PNG
+                }
+                endOffset++;
+            }
+        }
+        offset++;
+    }
+}
+
+int main(int argc, char* argv[]) {
+    if (argc < 3) {
+        std::cerr << "Usage: " << argv[0] << " <input_file> <output_dir>" << std::endl;
+        return 1;
+    }
+
+    const std::string filename = argv[1]; // Take the input file from command-line argument
+    const std::string outdir = argv[2];
+    std::vector<uint8_t> buffer;
+
+    if (readFileToBuffer(filename, buffer)) {
+        extractPNGs(outdir, buffer);
+    }
+
+    return 0;
+}