From 186f36beea8df7c51cf55769350b1cfd982d28a7 Mon Sep 17 00:00:00 2001
From: Misa <infoteddy@infoteddy.info>
Date: Sun, 18 Apr 2021 14:32:38 -0700
Subject: [PATCH] Add error checking to base path setup

Previously, if the game couldn't set the write dir to the base
directory, or couldn't make the base directory, or couldn't calculate
the base directory, it would probably dereference NULL or read from
uninitialized memory or murder your family or something. But now, I've
eliminated the potential Undefined Behavior from the code dealing with
the base path.
---
 desktop_version/src/FileSystemUtils.cpp | 91 ++++++++++++++++++++++---
 1 file changed, 81 insertions(+), 10 deletions(-)

diff --git a/desktop_version/src/FileSystemUtils.cpp b/desktop_version/src/FileSystemUtils.cpp
index 00412744..f7bd8402 100644
--- a/desktop_version/src/FileSystemUtils.cpp
+++ b/desktop_version/src/FileSystemUtils.cpp
@@ -39,7 +39,7 @@ static char levelDir[MAX_PATH] = {'\0'};
 static char assetDir[MAX_PATH] = {'\0'};
 static char virtualMountPath[MAX_PATH] = {'\0'};
 
-static void PLATFORM_getOSDirectory(char* output, const size_t output_size);
+static int PLATFORM_getOSDirectory(char* output, const size_t output_size);
 static void PLATFORM_migrateSaveData(char* output);
 static void PLATFORM_copyFile(const char *oldLocation, const char *newLocation);
 
@@ -70,7 +70,16 @@ int FILESYSTEM_init(char *argvZero, char* baseDir, char *assetsPath)
 	char* basePath;
 
 	PHYSFS_setAllocator(&allocator);
-	PHYSFS_init(argvZero);
+
+	if (!PHYSFS_init(argvZero))
+	{
+		printf(
+			"Unable to initialize PhysFS: %s\n",
+			PHYSFS_getErrorByCode(PHYSFS_getLastErrorCode())
+		);
+		return 0;
+	}
+
 	PHYSFS_permitSymbolicLinks(1);
 
 	/* Determine the OS user directory */
@@ -84,14 +93,30 @@ int FILESYSTEM_init(char *argvZero, char* baseDir, char *assetsPath)
 			!trailing_pathsep ? pathSep : ""
 		);
 	}
-	else
+	else if (!PLATFORM_getOSDirectory(output, sizeof(output)))
 	{
-		PLATFORM_getOSDirectory(output, sizeof(output));
+		return 0;
 	}
 
 	/* Mount our base user directory */
-	PHYSFS_mount(output, NULL, 0);
-	PHYSFS_setWriteDir(output);
+	if (!PHYSFS_mount(output, NULL, 0))
+	{
+		printf(
+			"Could not mount %s: %s\n",
+			output,
+			PHYSFS_getErrorByCode(PHYSFS_getLastErrorCode())
+		);
+		return 0;
+	}
+	if (!PHYSFS_setWriteDir(output))
+	{
+		printf(
+			"Could not set write dir to %s: %s\n",
+			output,
+			PHYSFS_getErrorByCode(PHYSFS_getLastErrorCode())
+		);
+		return 0;
+	}
 	printf("Base directory: %s\n", output);
 
 	/* Store full save directory */
@@ -707,17 +732,63 @@ void FILESYSTEM_enumerateLevelDirFileNames(
 	}
 }
 
-static void PLATFORM_getOSDirectory(char* output, const size_t output_size)
+static int PLATFORM_getOSDirectory(char* output, const size_t output_size)
 {
 #ifdef _WIN32
 	/* This block is here for compatibility, do not touch it! */
 	WCHAR utf16_path[MAX_PATH];
-	SHGetFolderPathW(NULL, CSIDL_PERSONAL, NULL, SHGFP_TYPE_CURRENT, utf16_path);
-	WideCharToMultiByte(CP_UTF8, 0, utf16_path, -1, output, output_size, NULL, NULL);
+	HRESULT retcode = SHGetFolderPathW(
+		NULL,
+		CSIDL_PERSONAL,
+		NULL,
+		SHGFP_TYPE_CURRENT,
+		utf16_path
+	);
+	int num_bytes;
+
+	if (FAILED(retcode))
+	{
+		printf(
+			"Could not get OS directory: SHGetFolderPathW returned 0x%08x\n",
+			retcode
+		);
+		return 0;
+	}
+
+	num_bytes = WideCharToMultiByte(
+		CP_UTF8,
+		0,
+		utf16_path,
+		-1,
+		output,
+		output_size,
+		NULL,
+		NULL
+	);
+	if (num_bytes == 0)
+	{
+		printf(
+			"Could not get OS directory: UTF-8 conversion failed with %d\n",
+			GetLastError()
+		);
+		return 0;
+	}
+
 	SDL_strlcat(output, "\\VVVVVV\\", MAX_PATH);
 	mkdir(output, 0777);
+	return 1;
 #else
-	SDL_strlcpy(output, PHYSFS_getPrefDir("distractionware", "VVVVVV"), output_size);
+	const char* prefDir = PHYSFS_getPrefDir("distractionware", "VVVVVV");
+	if (prefDir == NULL)
+	{
+		printf(
+			"Could not get OS directory: %s\n",
+			PHYSFS_getErrorByCode(PHYSFS_getLastErrorCode())
+		);
+		return 0;
+	}
+	SDL_strlcpy(output, prefDir, output_size);
+	return 1;
 #endif
 }