Fix compiler warnings and improve code quality

- Replace unsafe strcpy with strcpy_s for better security
- Fix DLL binding issues by adding PRIVATEBIN_API macros
- Add explicit type casts to resolve size conversion warnings
- Replace unsafe getenv with _dupenv_s for better security
- Add PRIVATEBINAPI_EXPORTS definition in CMakeLists.txt
- Improve CMake configuration for better build compatibility

CMakeLists.txt

@@ -40,6 +40,9 @@ set(HEADERS
 # Create the shared library
 add_library(privatebinapi SHARED ${SOURCES} ${HEADERS})
 
+# Define PRIVATEBINAPI_EXPORTS for the library build
+target_compile_definitions(privatebinapi PRIVATE PRIVATEBINAPI_EXPORTS)
+
 # Include directories
 target_include_directories(privatebinapi PUBLIC 
     ${CMAKE_CURRENT_SOURCE_DIR}/include

src/base58.cpp

@@ -16,7 +16,7 @@ std::string Base58::encode(const std::vector<unsigned char>& data) {
     }
     
     // Convert to base58
-    std::vector<unsigned char> digits((data.size() - leading_zeros) * 138 / 100 + 1);
+    std::vector<unsigned char> digits(static_cast<size_t>((data.size() - leading_zeros) * 138 / 100 + 1));
     size_t digitslen = 1;
     
     for (size_t i = leading_zeros; i < data.size(); i++) {

src/crypto.cpp

@@ -45,13 +45,13 @@ std::vector<unsigned char> Crypto::encrypt(const std::vector<unsigned char>& pla
         encryption.EncryptAndAuthenticate(
             ciphertext.data(), 
             auth_tag.data(),
-            auth_tag.size(),
+            static_cast<int>(auth_tag.size()),
             iv.data(), 
-            iv.size(),
+            static_cast<int>(iv.size()),
             nullptr, 
             0,  // Additional authenticated data
             plaintext.data(), 
-            plaintext.size()
+            static_cast<int>(plaintext.size())
         );
         
         return ciphertext;
@@ -79,13 +79,13 @@ std::vector<unsigned char> Crypto::decrypt(const std::vector<unsigned char>& cip
         bool valid = decryption.DecryptAndVerify(
             plaintext.data(),
             auth_tag.data(),
-            auth_tag.size(),
+            static_cast<int>(auth_tag.size()),
             iv.data(),
-            iv.size(),
+            static_cast<int>(iv.size()),
             nullptr,
             0,  // Additional authenticated data
             ciphertext.data(),
-            ciphertext.size()
+            static_cast<int>(ciphertext.size())
         );
         
         if(!valid) {

src/privatebinapi.cpp

@@ -26,14 +26,14 @@ static void copy_string_to_output(const std::string& source, char** destination)
     if (destination) {
         *destination = static_cast<char*>(malloc(source.length() + 1));
         if (*destination) {
-            std::strcpy(*destination, source.c_str());
+            strcpy_s(*destination, source.length() + 1, source.c_str());
         }
     }
 }
 
 extern "C" {
 
-int create_paste(const char* server_url, const char* content, 
+PRIVATEBIN_API int create_paste(const char* server_url, const char* content, 
                  const char* password, const char* expiration,
                  const char* format, int burn_after_reading, 
                  int open_discussion, char** paste_url, 
@@ -128,10 +128,10 @@ int create_paste(const char* server_url, const char* content,
     }
 }
 
-int upload_file(const char* server_url, const char* file_path,
-                const char* password, const char* expiration,
-                int burn_after_reading, int open_discussion,
-                char** paste_url, char** delete_token) {
+PRIVATEBIN_API int upload_file(const char* server_url, const char* file_path,
+               const char* password, const char* expiration,
+               int burn_after_reading, int open_discussion,
+               char** paste_url, char** delete_token) {
     
     if (!server_url || !file_path) {
         return ERROR_INVALID_INPUT;
@@ -248,7 +248,7 @@ int upload_file(const char* server_url, const char* file_path,
     }
 }
 
-int get_paste(const char* server_url, const char* paste_id, 
+PRIVATEBIN_API int get_paste(const char* server_url, const char* paste_id, 
               const char* key, char** content) {
     
     if (!server_url || !paste_id || !key || !content) {
@@ -305,7 +305,7 @@ int get_paste(const char* server_url, const char* paste_id,
     }
 }
 
-int delete_paste(const char* server_url, const char* paste_id, 
+PRIVATEBIN_API int delete_paste(const char* server_url, const char* paste_id, 
                  const char* delete_token) {
     
     if (!server_url || !paste_id || !delete_token) {
@@ -347,7 +347,7 @@ int delete_paste(const char* server_url, const char* paste_id,
     }
 }
 
-void free_string(char* str) {
+PRIVATEBIN_API void free_string(char* str) {
     if (str) {
         free(str);
     }

tests/test_basic.cpp

@@ -21,9 +21,12 @@ static bool extract_paste_id_and_key(const std::string& full_url, std::string& p
 }
 
 int main() {
-    const char* it = std::getenv("PRIVATEBIN_IT");
+    char* it = nullptr;
+    size_t len = 0;
+    _dupenv_s(&it, &len, "PRIVATEBIN_IT");
     if (!it || std::string(it) == "0") {
         std::cout << "[test] PRIVATEBIN_IT not set; skipping integration test." << std::endl;
+        free(it);
         return 0; // treat as success when integration testing is disabled
     }