RCT2 Steam path locator: improve OS support

Now looks for RCT2 install within OS-specific steam install directories.
Also checks the registry in Windows in case Steam has a custom install
path.

src/openrct2/config/Config.cpp

@@ -614,6 +614,17 @@ namespace Config
                 return location;
             }
         }
+
+        utf8 steamPath[2048] = { 0 };
+        if (platform_get_steam_path(steamPath, sizeof(steamPath)))
+        {
+            std::string location = Path::Combine(steamPath, "Rollercoaster Tycoon 2");
+            if (platform_original_game_data_exists(location.c_str()))
+            {
+                return location;
+            }
+        }
+
         if (platform_original_game_data_exists(gExePath))
         {
             return gExePath;

src/openrct2/platform/linux.c

@@ -34,6 +34,7 @@
 #endif // NO_TTF
 #include <fnmatch.h>
 #include <locale.h>
+#include <pwd.h>
 
 #include "../config/Config.h"
 #include "../localisation/language.h"
@@ -253,6 +254,52 @@ void platform_get_changelog_path(utf8 *outPath, size_t outSize)
     safe_strcat_path(outPath, "changelog.txt", outSize);
 }
 
+bool platform_get_steam_path(utf8 * outPath, size_t outSize)
+{
+    const char * steamRoot = getenv("STEAMROOT");
+    if (steamRoot != NULL)
+    {
+        safe_strcpy(outPath, steamRoot, outSize);
+        safe_strcat_path(outPath, "steamapps/common", outSize);
+        return true;
+    }
+
+    char steamPath[1024] = { 0 };
+    const char * localSharePath = getenv("XDG_DATA_HOME");
+    if (localSharePath != NULL)
+    {
+        safe_strcpy(steamPath, localSharePath, sizeof(steamPath));
+        safe_strcat_path(steamPath, "Steam/steamapps/common", sizeof(steamPath));
+        if (platform_directory_exists(steamPath))
+        {
+            safe_strcpy(outPath, steamPath, outSize);
+            return true;
+        }
+    }
+
+    const char * homeDir = getpwuid(getuid())->pw_dir;
+    if (homeDir != NULL)
+    {
+        safe_strcpy(steamPath, homeDir, sizeof(steamPath));
+        safe_strcat_path(steamPath, ".local/share/Steam/steamapps/common", sizeof(steamPath));
+        if (platform_directory_exists(steamPath))
+        {
+            safe_strcpy(outPath, steamPath, outSize);
+            return true;
+        }
+
+        memset(steamPath, 0, sizeof(steamPath));
+        safe_strcpy(steamPath, homeDir, sizeof(steamPath));
+        safe_strcat_path(steamPath, ".steam/steam/steamapps/common", sizeof(steamPath));
+        if (platform_directory_exists(steamPath))
+        {
+            safe_strcpy(outPath, steamPath, outSize);
+            return true;
+        }
+    }
+    return false;
+}
+
 #ifndef NO_TTF
 bool platform_get_font_path(TTFFontDescriptor *font, utf8 *buffer, size_t size)
 {

src/openrct2/platform/macos.m

@@ -19,6 +19,7 @@
 @import AppKit;
 @import Foundation;
 #include <mach-o/dyld.h>
+#include <pwd.h>
 #include "platform.h"
 #include "../util/util.h"
 #include "../localisation/language.h"
@@ -215,4 +216,21 @@ void platform_get_changelog_path(utf8 *outPath, size_t outSize)
     safe_strcat_path(outPath, "changelog.txt", outSize);
 }
 
+bool platform_get_steam_path(utf8 * outPath, size_t outSize)
+{
+    char steamPath[1024] = { 0 };
+    const char * homeDir = getpwuid(getuid())->pw_dir;
+    if (homeDir != NULL)
+    {
+        safe_strcpy(steamPath, homeDir, sizeof(steamPath));
+        safe_strcat_path(steamPath, "Library/Application Support/Steam/steamapps/common", sizeof(steamPath));
+        if (platform_directory_exists(steamPath))
+        {
+            safe_strcpy(outPath, steamPath, outSize);
+            return true;
+        }
+    }
+    return false;
+}
+
 #endif

src/openrct2/platform/platform.h

@@ -135,6 +135,7 @@ uint8 platform_get_locale_temperature_format();
 uint8 platform_get_locale_date_format();
 bool platform_process_is_elevated();
 void platform_get_changelog_path(utf8 *outPath, size_t outSize);
+bool platform_get_steam_path(utf8 * outPath, size_t outSize);
 
 #ifndef NO_TTF
 bool platform_get_font_path(TTFFontDescriptor *font, utf8 *buffer, size_t size);

src/openrct2/platform/posix.c

@@ -27,6 +27,7 @@
 #include <libgen.h>
 #include <locale.h>
 #include <pwd.h>
+#include <stdlib.h>
 #include <sys/file.h>
 #include <sys/stat.h>
 #include <sys/time.h>

src/openrct2/platform/windows.c

@@ -506,6 +506,37 @@ void platform_get_user_directory(utf8 *outPath, const utf8 *subDirectory, size_t
     }
 }
 
+bool platform_get_steam_path(utf8 * outPath, size_t outSize)
+{
+    wchar_t * wSteamPath;
+    HKEY hKey;
+    DWORD type, size;
+    LRESULT result;
+
+    if (RegOpenKeyW(HKEY_CURRENT_USER, L"Software\\Valve\\Steam", &hKey) != ERROR_SUCCESS)
+        return false;
+
+    // Get the size of the path first
+    if (RegQueryValueExW(hKey, L"SteamPath", 0, &type, NULL, &size) != ERROR_SUCCESS)
+    {
+        RegCloseKey(hKey);
+        return false;
+    }
+
+    wSteamPath = (wchar_t*)malloc(size);
+    result = RegQueryValueExW(hKey, L"SteamPath", 0, &type, (LPBYTE)wSteamPath, &size);
+    if (result == ERROR_SUCCESS)
+    {
+        utf8 * utf8SteamPath = widechar_to_utf8(wSteamPath);
+        safe_strcpy(outPath, utf8SteamPath, outSize);
+        safe_strcat_path(outPath, "steamapps\\common", outSize);
+        free(utf8SteamPath);
+    }
+    free(wSteamPath);
+    RegCloseKey(hKey);
+    return result == ERROR_SUCCESS;
+}
+
 /**
  *
  *  rct2: 0x00407978