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common/SteamAppStartup.cpp

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+//========= Copyright Valve Corporation, All rights reserved. ============//
+//
+// Purpose: 
+//
+//=============================================================================//
+
+#ifdef _WIN32
+#include "SteamAppStartup.h"
+
+#define WIN32_LEAN_AND_MEAN
+#include <assert.h>
+#include <windows.h>
+#include <process.h>
+#include <direct.h>
+#include <stdio.h>
+#include <sys/stat.h>
+
+#define STEAM_PARM "-steam"
+
+void LaunchSelfViaSteam(const char *params);
+
+bool FileExists(const char *fileName)
+{
+	struct _stat statbuf;
+	return (_stat(fileName, &statbuf) == 0);
+}
+
+//-----------------------------------------------------------------------------
+// Purpose: Launches steam if necessary
+//-----------------------------------------------------------------------------
+bool ShouldLaunchAppViaSteam(const char *lpCmdLine, const char *steamFilesystemDllName, const char *stdioFilesystemDllName)
+{
+	// see if steam is on the command line
+	const char *steamStr = strstr(lpCmdLine, STEAM_PARM);
+
+	// check the character following it is a whitespace or null
+	if (steamStr)
+	{
+		const char *postChar = steamStr + strlen(STEAM_PARM);
+		if (*postChar == 0 || isspace(*postChar))
+		{
+			// we're running under steam already, let the app continue
+			return false;
+		}
+	}
+
+	// we're not running under steam, see which filesystems are available
+	if (FileExists(stdioFilesystemDllName))
+	{
+		// we're being run with a stdio filesystem, so we can continue without steam
+		return false;
+	}
+
+	// make sure we have a steam filesystem available
+	if (!FileExists(steamFilesystemDllName))
+	{
+		return false;
+	}
+
+	// we have the steam filesystem, and no stdio filesystem, so we must need to be run under steam
+	// launch steam
+	LaunchSelfViaSteam(lpCmdLine);
+	return true;
+}
+
+//-----------------------------------------------------------------------------
+// Purpose: Handles launching the game indirectly via steam
+//-----------------------------------------------------------------------------
+void LaunchSelfViaSteam(const char *params)
+{
+	// calculate the details of our launch
+	char appPath[MAX_PATH];
+	::GetModuleFileName((HINSTANCE)GetModuleHandle(NULL), appPath, sizeof(appPath));
+
+	// strip out the exe name
+	char *slash = strrchr(appPath, '\\');
+	if (slash)
+	{
+		*slash = 0;
+	}
+
+	// save out our details to the registry
+	HKEY hKey;
+	if (ERROR_SUCCESS == RegOpenKey(HKEY_CURRENT_USER, "Software\\Valve\\Steam", &hKey)) 
+	{
+		DWORD dwType = REG_SZ;
+		DWORD dwSize = static_cast<DWORD>( strlen(appPath) + 1 );
+		RegSetValueEx(hKey, "TempAppPath", NULL, dwType, (LPBYTE)appPath, dwSize);
+		dwSize = static_cast<DWORD>( strlen(params) + 1 );
+		RegSetValueEx(hKey, "TempAppCmdLine", NULL, dwType, (LPBYTE)params, dwSize);
+		// clear out the appID (since we don't know it yet)
+		dwType = REG_DWORD;
+		int appID = -1;
+		RegSetValueEx(hKey, "TempAppID", NULL, dwType, (LPBYTE)&appID, sizeof(appID));
+		RegCloseKey(hKey);
+	}
+
+	// search for an active steam instance
+	HWND hwnd = ::FindWindow("Valve_SteamIPC_Class", "Hidden Window");
+	if (hwnd)
+	{
+		::PostMessage(hwnd, WM_USER + 3, 0, 0);
+	}
+	else
+	{
+		// couldn't find steam, find and launch it
+		
+		// first, search backwards through our current set of directories
+		char steamExe[MAX_PATH];
+		steamExe[0] = 0;
+		char dir[MAX_PATH];
+		if (::GetCurrentDirectoryA(sizeof(dir), dir))
+		{
+			char *slash = strrchr(dir, '\\');
+			while (slash)
+			{
+				// see if steam_dev.exe is in the directory first
+				slash[1] = 0;
+				strcat(slash, "steam_dev.exe");
+				FILE *f = fopen(dir, "rb");
+				if (f)
+				{
+					// found it
+					fclose(f);
+					strcpy(steamExe, dir);
+					break;
+				}
+
+				// see if steam.exe is in the directory
+				slash[1] = 0;
+				strcat(slash, "steam.exe");
+				f = fopen(dir, "rb");
+				if (f)
+				{
+					// found it
+					fclose(f);
+					strcpy(steamExe, dir);
+					break;
+				}
+
+				// kill the string at the slash
+				slash[0] = 0;
+
+				// move to the previous slash
+				slash = strrchr(dir, '\\');
+			}
+		}
+
+		if (!steamExe[0])
+		{
+			// still not found, use the one in the registry
+			HKEY hKey;
+			if (ERROR_SUCCESS == RegOpenKey(HKEY_CURRENT_USER, "Software\\Valve\\Steam", &hKey)) 
+			{
+				DWORD dwType;
+				DWORD dwSize = sizeof(steamExe);
+				RegQueryValueEx( hKey, "SteamExe", NULL, &dwType, (LPBYTE)steamExe, &dwSize);
+				RegCloseKey( hKey );
+			}
+		}
+		
+		if (!steamExe[0])
+		{
+			// still no path, error
+			::MessageBox(NULL, "Error running game: could not find steam.exe to launch", "Fatal Error", MB_OK | MB_ICONERROR);
+			return;
+		}
+
+		// fix any slashes
+		for (char *slash = steamExe; *slash; slash++)
+		{
+			if (*slash == '/')
+			{
+				*slash = '\\';
+			}
+		}
+
+		// change to the steam directory
+		strcpy(dir, steamExe);
+		char *delimiter = strrchr(dir, '\\');
+		if (delimiter)
+		{
+			*delimiter = 0;
+			_chdir(dir);
+		}
+
+		// exec steam.exe, in silent mode, with the launch app param
+		char *args[4] = { steamExe, "-silent", "-applaunch", NULL };
+		_spawnv(_P_NOWAIT, steamExe, args);
+	}
+}
+
+#endif // _WIN32