allow to read files virtually from memory stream

sources/dunelegacy/FileClasses/FileManager.cpp

@@ -129,6 +129,17 @@ std::vector<std::string> FileManager::getMissingFiles() {
 sdl2::RWops_ptr FileManager::openFile(const std::string& filename) {
     sdl2::RWops_ptr ret;
 
+    // try loading memory file
+    {
+        auto it = memoryFiles.find(strToUpper(filename));
+        if (it != memoryFiles.end()) {
+            ret = sdl2::RWops_ptr{SDL_RWFromConstMem(it->second.first, it->second.second)};
+            if(ret) {
+                return ret;
+            }
+        }
+    }
+
     // try loading external file
     for(const auto& searchPath : getSearchPath()) {
         auto externalFilename = searchPath + "/";
@@ -153,6 +164,10 @@ sdl2::RWops_ptr FileManager::openFile(const std::string& filename) {
 
 bool FileManager::exists(const std::string& filename) const {
 
+    if (memoryFiles.find(strToUpper(filename)) != memoryFiles.end()) {
+        return true;
+    }
+
     // try finding external file
     for(const std::string& searchPath : getSearchPath()) {
         auto externalFilename = searchPath + "/";
@@ -172,6 +187,11 @@ bool FileManager::exists(const std::string& filename) const {
     return false;
 }
 
+void FileManager::insertMemoryFile(const std::string &filename, const void *data, size_t length)
+{
+    memoryFiles[strToUpper(filename)] = {data, length};
+}
+
 
 std::string FileManager::md5FromFilename(const std::string& filename) const {
     unsigned char md5sum[16];

sources/dunelegacy/FileClasses/FileManager.h

@@ -23,6 +23,7 @@
 
 #include <string>
 #include <vector>
+#include <map>
 #include <memory>
 
 /// A class for loading all the PAK-Files.
@@ -59,10 +60,14 @@ class FileManager final {
     sdl2::RWops_ptr openFile(const std::string& filename);
 
     bool exists(const std::string& filename) const;
+
+    void insertMemoryFile(const std::string &filename, const void *data, size_t length);
 private:
     std::string md5FromFilename(const std::string& filename) const;
 
     std::vector<std::unique_ptr<Pakfile>> pakFiles;
+
+    std::map<std::string, std::pair<const void *, size_t>> memoryFiles;
 };
 
 #endif // FILEMANAGER_H

sources/dunemusic.cpp

@@ -21,7 +21,12 @@ DUNEMUSIC_EXPORT
 void DuneMusic_Init(int sampleRate, const char *dataDirectory, DuneMusicOplEmu oplEmu)
 {
     Mix_OpenAudio(sampleRate, MIX_DEFAULT_FORMAT, 2, 1024);
-    duneLegacyDataDir.assign(dataDirectory);
+
+    if (dataDirectory && dataDirectory[0])
+        duneLegacyDataDir.assign(dataDirectory);
+    else
+        duneLegacyDataDir.assign(".");
+
     pFileManager.reset(new FileManager);
     SoundAdlibPC::s_oplEmu = oplEmu;
     sPlayer.reset(new ADLPlayer);
@@ -35,6 +40,12 @@ void DuneMusic_Quit()
     Mix_CloseAudio();
 }
 
+DUNEMUSIC_EXPORT
+void DuneMusic_InsertMemoryFile(const char *filename, const void *data, size_t length)
+{
+    pFileManager->insertMemoryFile(filename, data, length);
+}
+
 DUNEMUSIC_EXPORT
 void DuneMusic_GetSamples(int16_t *buf, unsigned count)
 {

sources/dunemusic.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <stdint.h>
+#include <stddef.h>
 
 #ifdef __cplusplus
 extern "C" {
@@ -17,6 +18,8 @@ void DuneMusic_Quit();
 
 void DuneMusic_GetSamples(int16_t *buf, unsigned count);
 
+void DuneMusic_InsertMemoryFile(const char *filename, const void *data, size_t length);
+
 typedef enum DuneMusicType {
     kMusicAttack = 0,   /*!< Played when at least one of player's units was hit. */
     kMusicPeace,        /*!< Played most of the time when the enemy is not attacking. */