Make Quake II compatible with unicode directory names

This changes employs a horrible hack to connect the ASCII Quake II to
the UTF-16 WinAPI. The path to "My Documentes" is read in UTF-16, then
converted to a old "DOS style path" with 8.3 characters. This DOS path
has by convention no UTF-16 characters in it and can be converted into
a normal ASCII string. This ASCII string is the path used by Yamagi
Quake II. The conversion logic will fail if the "Windows to DOS
filename transistion" is deactivated in the registry (it's on by
default). In that case no homedir is used and the "Windows Roaming
Mechanism" kicks in.

TODO

@@ -42,19 +42,7 @@ Long term TODO list for Quake II on Windows
    implementation is rather invasive into the console
    subsystem and I don't think that it's worth the efford.
 
-4. The unicode issue:
-   Quake II only allows ASCII characters, internally all
-   characters are represented as "char". But Windows uses
-   unicode quite often. This may lead to problems. The big
-   question is: "What happens, if the path to the home dir
-   contains unicode characters?" At what can we do to prevent
-   problems without rewriting the whole game to be unicode
-   aware? This may be a problem on Linux and FreeBSD too,
-   but at least on FreeBSD unicode characters in the user-
-   name are a bad idea and for things to work correctly
-   the homedir-name should be the same as the username...
-
-5. The debug / stdout issue:
+4. The debug / stdout issue:
    At the moment no stdout is readable on windows, the only
    way is to scroll in the console. This is a problem, because
    without the game output problems are hard to debug. Enabling
@@ -70,7 +58,7 @@ Long term TODO list for Quake II on Windows
    While I'm not sure that gdb can read Windows crashdumps,
    it may be worth to take a deeper look into this.
 
-6. The CR-LF issue:
+5. The CR-LF issue:
    At the moment all files have LF line endings, which are
    incompatible with most Windows software. This isn't a
    problem for the code itself (at least with MinGW), but

src/common/header/shared.h

@@ -55,7 +55,7 @@ typedef enum {false, true}  qboolean;
 #define MAX_QPATH 64                /* max length of a quake game pathname */
 
 #ifdef _WIN32
-#define MAX_OSPATH 256              /* max length of a filesystem pathname */
+#define MAX_OSPATH 256             /* max length of a filesystem pathname (same as MAX_PATH) */
 #else
 #define MAX_OSPATH 128              /* max length of a filesystem pathname */
 #endif

src/windows/system.c

@@ -610,12 +610,46 @@ Sys_GetCurrentDirectory(void)
 char *
 Sys_GetHomeDir(void)
 {
-	char *old;
 	char *cur;
+	char *old;
+	char profile[MAX_PATH];
+	int len;
 	static char gdir[MAX_OSPATH];
-	TCHAR profile[MAX_OSPATH];
+	WCHAR sprofile[MAX_PATH];
+	WCHAR uprofile[MAX_PATH];
 
-    SHGetFolderPath(NULL, CSIDL_PERSONAL, NULL, 0, profile);
+	/* The following lines implement a horrible
+	   hack to connect the UTF-16 WinAPI to the
+	   ASCII Quake II. While this should work in
+	   most cases, it'll fail if the "Windows to
+	   DOS filename translation" is switched off.
+	   In that case the function will return NULL
+	   and no homedir is used. */
+
+	/* Get the path to "My Documents" directory */
+	SHGetFolderPathW(NULL, CSIDL_PERSONAL, NULL, 0, uprofile);
+
+	/* Create a UTF-16 DOS path */
+    len = GetShortPathNameW(uprofile, sprofile, sizeof(sprofile));
+
+	if (len == 0)
+	{
+		return NULL;
+	}
+
+	/* Since the DOS path contains no UTF-16 characters, just convert it to ASCII */
+	WideCharToMultiByte(CP_ACP, 0, sprofile, -1, profile, sizeof(profile), NULL, NULL);
+
+	if (len == 0)
+	{
+		return NULL;
+	}
+
+	/* Check if path is too long */
+    if ((len + strlen(CFGDIR) -1) >= 256)
+	{
+		return NULL;
+	}
 
 	/* Replace backslashes by slashes */
 	cur = old = profile;