Core: Handle relative paths for saves, screenshots, etc consistently (fixes #2826)

CHANGES

@@ -28,6 +28,7 @@ Other fixes:
  - Scripting: Fix receiving packets for client sockets
  - Scripting: Fix empty receive calls returning unknown error on Windows
 Misc:
+ - Core: Handle relative paths for saves, screenshots, etc consistently (fixes mgba.io/i/2826)
  - GB Serialize: Add missing savestate support for MBC6 and NT (newer)
  - GBA: Improve detection of valid ELF ROMs
  - Qt: Include wayland QPA in AppImage (fixes mgba.io/i/2796)

CMakeLists.txt

@@ -338,6 +338,8 @@ find_function(popcount32)
 find_function(futimens)
 find_function(futimes)
 
+find_function(realpath)
+
 if(ANDROID AND ANDROID_NDK_MAJOR GREATER 13)
 	find_function(localtime_r)
 	set(HAVE_STRTOF_L ON)

include/mgba-util/vfs.h

@@ -100,6 +100,9 @@ struct VFile* VFileFromFILE(FILE* file);
 
 void separatePath(const char* path, char* dirname, char* basename, char* extension);
 
+bool isAbsolute(const char* path);
+void makeAbsolute(const char* path, const char* base, char* out);
+
 struct VFile* VDirFindFirst(struct VDir* dir, bool (*filter)(struct VFile*));
 struct VFile* VDirFindNextAvailable(struct VDir*, const char* basename, const char* infix, const char* suffix, int mode);
 

src/core/directories.c

@@ -116,10 +116,15 @@ struct VFile* mDirectorySetOpenSuffix(struct mDirectorySet* dirs, struct VDir* d
 }
 
 void mDirectorySetMapOptions(struct mDirectorySet* dirs, const struct mCoreOptions* opts) {
+	char abspath[PATH_MAX + 1];
+	char configDir[PATH_MAX + 1];
+	mCoreConfigDirectory(configDir, sizeof(configDir));
+
 	if (opts->savegamePath) {
-		struct VDir* dir = VDirOpen(opts->savegamePath);
-		if (!dir && VDirCreate(opts->savegamePath)) {
-			dir = VDirOpen(opts->savegamePath);
+		makeAbsolute(opts->savegamePath, configDir, abspath);
+		struct VDir* dir = VDirOpen(abspath);
+		if (!dir && VDirCreate(abspath)) {
+			dir = VDirOpen(abspath);
 		}
 		if (dir) {
 			if (dirs->save && dirs->save != dirs->base) {
@@ -130,9 +135,10 @@ void mDirectorySetMapOptions(struct mDirectorySet* dirs, const struct mCoreOptio
 	}
 
 	if (opts->savestatePath) {
-		struct VDir* dir = VDirOpen(opts->savestatePath);
-		if (!dir && VDirCreate(opts->savestatePath)) {
-			dir = VDirOpen(opts->savestatePath);
+		makeAbsolute(opts->savestatePath, configDir, abspath);
+		struct VDir* dir = VDirOpen(abspath);
+		if (!dir && VDirCreate(abspath)) {
+			dir = VDirOpen(abspath);
 		}
 		if (dir) {
 			if (dirs->state && dirs->state != dirs->base) {
@@ -143,9 +149,10 @@ void mDirectorySetMapOptions(struct mDirectorySet* dirs, const struct mCoreOptio
 	}
 
 	if (opts->screenshotPath) {
-		struct VDir* dir = VDirOpen(opts->screenshotPath);
-		if (!dir && VDirCreate(opts->screenshotPath)) {
-			dir = VDirOpen(opts->screenshotPath);
+		makeAbsolute(opts->screenshotPath, configDir, abspath);
+		struct VDir* dir = VDirOpen(abspath);
+		if (!dir && VDirCreate(abspath)) {
+			dir = VDirOpen(abspath);
 		}
 		if (dir) {
 			if (dirs->screenshot && dirs->screenshot != dirs->base) {
@@ -156,9 +163,10 @@ void mDirectorySetMapOptions(struct mDirectorySet* dirs, const struct mCoreOptio
 	}
 
 	if (opts->patchPath) {
-		struct VDir* dir = VDirOpen(opts->patchPath);
-		if (!dir && VDirCreate(opts->patchPath)) {
-			dir = VDirOpen(opts->patchPath);
+		makeAbsolute(opts->patchPath, configDir, abspath);
+		struct VDir* dir = VDirOpen(abspath);
+		if (!dir && VDirCreate(abspath)) {
+			dir = VDirOpen(abspath);
 		}
 		if (dir) {
 			if (dirs->patch && dirs->patch != dirs->base) {
@@ -169,9 +177,10 @@ void mDirectorySetMapOptions(struct mDirectorySet* dirs, const struct mCoreOptio
 	}
 
 	if (opts->cheatsPath) {
-		struct VDir* dir = VDirOpen(opts->cheatsPath);
-		if (!dir && VDirCreate(opts->cheatsPath)) {
-			dir = VDirOpen(opts->cheatsPath);
+		makeAbsolute(opts->cheatsPath, configDir, abspath);
+		struct VDir* dir = VDirOpen(abspath);
+		if (!dir && VDirCreate(abspath)) {
+			dir = VDirOpen(abspath);
 		}
 		if (dir) {
 			if (dirs->cheats && dirs->cheats != dirs->base) {

src/util/vfs.c

@@ -13,6 +13,10 @@
 #ifdef __3DS__
 #include <mgba-util/platform/3ds/3ds-vfs.h>
 #endif
+#ifdef _WIN32
+#include <shlwapi.h>
+#include <windows.h>
+#endif
 
 struct VFile* VFileOpen(const char* path, int flags) {
 #ifdef USE_VFS_FILE
@@ -207,6 +211,41 @@ void separatePath(const char* path, char* dirname, char* basename, char* extensi
 	}
 }
 
+bool isAbsolute(const char* path) {
+	// XXX: Is this robust?
+#ifdef _WIN32
+	WCHAR wpath[PATH_MAX];
+	MultiByteToWideChar(CP_UTF8, 0, path, -1, wpath, PATH_MAX);
+	return !PathIsRelativeW(wpath);
+#else
+	return path[0] == '/';
+#endif
+}
+
+void makeAbsolute(const char* path, const char* base, char* out) {
+	if (isAbsolute(path)) {
+		strncpy(out, path, PATH_MAX);
+		return;
+	}
+
+	char buf[PATH_MAX];
+	snprintf(buf, sizeof(buf), "%s" PATH_SEP "%s", base, path);
+#ifdef _WIN32
+	WCHAR wbuf[PATH_MAX];
+	WCHAR wout[PATH_MAX];
+	MultiByteToWideChar(CP_UTF8, 0, buf, -1, wbuf, PATH_MAX);
+	if (GetFullPathNameW(wbuf, PATH_MAX, wout, NULL)) {
+		WideCharToMultiByte(CP_UTF8, 0, wout, -1, out, PATH_MAX, 0, 0);
+		return;
+	}
+#elif defined(HAVE_REALPATH)
+	if (realpath(buf, out)) {
+		return;
+	}
+#endif
+	strncpy(out, buf, PATH_MAX);
+}
+
 struct VFile* VDirFindFirst(struct VDir* dir, bool (*filter)(struct VFile*)) {
 	dir->rewind(dir);
 	struct VDirEntry* dirent = dir->listNext(dir);