This is a hack to unix-ify the Hammer of Thyrion (uHexen2) command line.
Its purpose is to catch mis-spelt options such as "-fullscrren" and also
to print a comprehensive help message when desired.  It has two parts:

1. option_t data structure, which attempts to bring all the command line
args parsed by COM_CheckParm() into one place for validation upon program
startup.

2. C code which parses the command line, attempting to identify faulty
options, but also allowing for "+map e1m1" type args.

stevenaaus@yahoo.com


--- a/engine/hexen2/sys_unix.c
+++ b/engine/hexen2/sys_unix.c
@@ -601,65 +601,268 @@ static void PrintVersion (void)
 }
 
 #include "snd_sys.h"
-static const char *help_strings[] = {
-	"     [-v | --version]        Display version information",
+
+/* Summarise command line options and inspect for correctness.
+ * No attempt is made to validate arg type is integer or whatever.
+ * Note: dos, windows options are not handled here.
+ * S.A. 22 Jan 2009  */
+typedef struct
+{
+	const char	*option;
+	const char	*alias1;
+	const char	*alias2;
+	int		num_args; /* only 0, 1 (and -1:one optional arg) are currently implemented */
+	const char	*descrip; /* if option = "" , descrip is an help section title */
+} option_t;
+
+static option_t options[] =
+{
+/* GENERAL */
+	{"","","",0,"General"},
 #ifndef DEMOBUILD
 #   if defined(H2MP)
-	"     [-noportals]            Disable the mission pack support",
+	{"-noportals",	"",		"",	0, "Disable the mission pack support"},
 #   else
-	"     [-portals | -h2mp ]     Run the Portal of Praevus mission pack",
+	{"-portals",	"-h2mp",	"",	0, "Play Portal of Praevus mission pack"},
 #   endif
 #endif
+	{"-game",	"",		"",	1, "Play this mod"},
+	{"-basedir",	"",		"",	1, "Use this directory as base"},
+	{"-nomouse",	"",		"",	0, "Disable mouse"},
+	{"-heapsize",	"",		"",	1, "Kilobytes memory for heap"},
+	{"-v",		"--version",	"",	0, "Display version information"},
+	{"-h",		"--help",	"-?",	0, "Show help"},
+/* VIDEO */
+	{"","","",0,"Video"},
 #ifndef SVGAQUAKE
-	"     [-w | -window ]         Run the game windowed",
-	"     [-f | -fullscreen]      Run the game fullscreen",
+	{"-f",		"-fullscreen",	"",	0, "Run fullscreen"},
+	{"-w",		"-window",	"",	0, "Run as a window"},
 #endif
-	"     [-width X [-height Y]]  Select screen size",
+	{"-width",	"",		"",	1, "Set screen width"},
+	{"-height",	"",		"",	1, "Set screen height (requires -width)"},
+	{"-force",	"",		"",	0, "Skip some video sanity checks"},
+	{"-conwidth",	"",		"",	1, "Set console width (in pixels)"},
 #ifdef GLQUAKE
-	"     [-bpp]                  Depth for GL fullscreen mode",
-	"     [-vsync]                Enable sync with monitor refresh",
-	"     [-g | -gllibrary]       Select 3D rendering library",
-	"     [-fsaa N]               Enable N sample antialiasing",
-	"     [-paltex]               Enable 8-bit textures",
-	"     [-nomtex]               Disable multitexture detection/usage",
+	{"-bpp",	"",		"",	1, "Depth for GL fullscreen mode"},
+	{"-sync",	"-vsync",	"",	0, "Enable sync with monitor refresh"},
+	{"-g",		"-gllibrary",	"",	1, "Select 3D rendering library"},
+	{"-fsaa",	"",		"",	1, "Enable N sample antialiasing"},
+	{"-paltex",	"",		"",	0, "Enable 8-bit textures"},
+	{"-nomtex",	"",		"",	0, "Disable multitexture detection/usage"},
 #endif
+/* SOUND */
+	{"","","",0,"Sound"},
+
 #if !defined(_NO_SOUND)
 #if SOUND_NUMDRIVERS
-	"     [-s | -nosound]         Run the game without sound",
+	{"-s",		"-nosound",	"",	0, "Disable sound"},
 #endif
 #if (SOUND_NUMDRIVERS > 1)
 #if HAVE_OSS_SOUND
-	"     [-sndoss]               Use OSS sound",
+	{"-sndoss",	"",		"",	0, "Use OSS sound"},
 #endif
 #if HAVE_ALSA_SOUND
-	"     [-sndalsa]              Use ALSA sound (alsa > 1.0.1)",
+	{"-sndalsa",	"",		"",	0, "Use ALSA sound (alsa > 1.0.1)"},
 #endif
 #if HAVE_SUN_SOUND
-	"     [-sndsun | -sndbsd]     Use SUN / BSD sound",
+	{"-sndsun",	"-sndbsd",	"",	0, "Use SUN/BSD sound"},
 #endif
 #if HAVE_SDL_SOUND
-	"     [-sndsdl]               Use SDL sound",
+	{"-sndsdl",	"",		"",	0, "Use SDL sound"},
 #endif
 #endif	/*  SOUND_NUMDRIVERS */
 #endif	/* _NO_SOUND */
-	"     [-nomouse]              Disable mouse usage",
-	"     [-listen N]             Enable multiplayer with max N players",
-	"     [-heapsize Bytes]       Heapsize (memory to allocate)",
-	NULL
+	{"-sndspeed",	"",		"",	1, "Sound sampling rate"},
+	{"-sndbits",	"",		"",	1, "Sound sampling bits"},
+	{"-alsadev",	"",		"",	1, "Alsa device name"},
+	{"-ossdev",	"",		"",	1, "OSS device name"},
+	{"-sndmono",	"",		"",	0, "Set mono playback"},
+/* MUSIC */
+	{"","","",0,"Music"},
+
+	{"-nomidi",	"",		"",	0, "Disable midi device"},
+	{"-nocdaudio",	"",		"",	0, "Disable CD playback"},
+	{"-cddev",	"",		"",	1, "Use this CD device"},
+/* NETWORK */
+	{"","","",0,"Network"},
+
+	{"-listen",	"",		"",	-1, "Enable multiplayer with max N players"},
+	{"-dedicated",	"",		"",	-1, "Enable dedicated server with max N players"},
+	{"-nolan",	"",		"",	0, "Disable local area network"},
+	{"-noudp",	"",		"",	0, "Disable udp"},
+	{"-noifscan",	"",		"",	0, "Disable net interface scan"},
+	{"-ip",		"-bindip",	"",	1, "Use this IP address"},
+	{"-localip",	"",		"",	1, "Use this local IP address"},
+	{"-port",	"",		"",	1, "Use this port"},
+	{"-udpport",	"",		"",	1, "Use this udp port"},
+	{"-ipxport",	"",		"",	1, "Use this ipx port"},
+/* DEBUG */
+	{"","","",0,"Debugging"},
+
+	{"-condebug",	"-debuglog",	"",	0, "Do extra debug logging"},
+	{"-developer",	"",		"",	0, "Set developer cvar"},
+	{"-devlog",	"",		"",	0, "Log some dev events when !developer"},
+	{"-safemode",	"",		"",	0, "Disable some hardware features"},
+/* extra OPENGL */
+#ifdef GLQUAKE
+	{"","","",0,"Extra OpenGL"},
+
+	{"-lm_1",	"",		"",	0, "use GL_LUMINANCE light format"},
+	{"-lm_4",	"",		"",	0, "use GL_RGBA      light format"},
+# ifdef USE_3DFXGAMMA
+	{"-3dfxgamma",	"",		"",	0, "enable 3dfx gamma support"},
+# endif
+#endif
+/* SVGA */
+#ifdef SVGAQUAKE
+	{"","","",0,"SVGA"},
+	{"-mode",	"",		"",	1, "SVGA mode"},
+	{"-mdev",	"",		"",	1, "Use this mouse device"},
+	{"-mrate",	"",		"",	1, "Mouse sampling rate"},
+	{"-nokbd",	"",		"",	0, "Disable keyboard"},
+#endif
+/* MISCELLANEOUS */
+	{"","","",0,"Miscellaneous"},
+	{"-forcemem",	"",		"",	0, "Force memory option"},
+	{"-surfcachesize","",		"",	1, "Surface cache size"},
+	{"-protocol",	"",		"",	1, "Request different game version"},
+	{"-particles",	"",		"",	1, "Set number of particles"},
+	{"-fullsbar",	"",		"",	0, "Enable full status bar (unused)"},
+	{"-nojoy",	"",		"",	0, "Disable joystick"},
+	{"-zone",	"",		"",	1, "Zone memory size"},
+/* end used to terminate options */
+	{"end","","",0,""}
 };
 
-static void PrintHelp (const char *name)
+static void CheckArgs (int argc, char **argv)
 {
-	int i = 0;
+	/* Check each argv[] against the options registered above -
+	 * If it's not a valid option, exit with error message.
+	 * Else, skip checking the next option.num_arg argv[].
+	 * (num_args=-1 means a single argv[] is optional).
+	 * Also allow for game commands like "+r_shadow 1"  */
+	int	i, j, valid, skip;
+	int	num_avail_options;
+	char	string[40];
 
-	Sys_Printf ("Usage: %s [options]\n", name);
-	while (help_strings[i])
+	/* find how many options are registered */
+	for (i = 1; ; i++)
 	{
-		Sys_PrintTerm (help_strings[i]);
-		Sys_PrintTerm ("\n");
-		i++;
+		if (options[i].option[0] == 0)
+			continue;
+		if (strcmp(options[i].option, "end") == 0)
+			break;
+	}
+	num_avail_options = i;
+
+	if (argc <= 1)
+		return;
+
+	skip = 0;
+
+	for (i = 1; i < argc; i++)
+	{
+		if (skip == 1) {
+			/* one arg only */
+			skip = 0;
+			continue;
+		}
+		if (skip == -1) {
+			/* optional single arg */
+			skip = 0;
+			if (argv[i][0] != '-')
+				continue;
+		}
+		if (skip == -2) {
+			/* parsing +game_command */
+			/* +game command found... skip till we find an "-option" */
+			if (argv[i][0] != '-')
+				continue;
+			else
+				skip = 0;
+		}
+
+		if ( !strcmp(argv[i], "-v") || !strcmp(argv[i], "-version" ) ||
+			!strcmp(argv[i], "--version"))
+		{
+			exit(0);
+		}
+		if ( !strcmp(argv[i], "-h") || !strcmp(argv[i], "-help" ) ||
+			!strcmp(argv[i], "-?") || !strcmp(argv[i], "--help"))
+		{
+			Sys_Printf ("\nUsage: %s [options] [+gamecommands]\n", argv[0]);
+			for (j = 0; j < num_avail_options; j++)
+			{
+				if (options[j].option[0]) {
+				    sprintf (string, "     %s", options[j].option);
+				    if (options[j].alias1[0]) {
+					    strcat (string, " | ");
+					    strcat (string, options[j].alias1);
+				    }
+				    if (options[j].num_args == 1)
+					    strcat (string, " ARG");
+				    if (options[j].num_args == -1)
+					    strcat (string, " [ARG]");
+				    Sys_Printf  ("%-30s%s\n", string, options[j].descrip);
+				} else {
+				    /* print header */
+				    Sys_Printf  ("\n%s Options:\n", options[j].descrip);
+				}
+			}
+			exit (0);
+		}
+
+		valid = 0; /* check this arg is valid */
+
+		for (j = 0; j < num_avail_options; j++)
+		{
+			if (!options[j].option[0]) 
+				continue;
+
+			valid = (strcmp(options[j].option, argv[i]) == 0) |
+				(strcmp(options[j].alias1, argv[i]) == 0) |
+				(strcmp(options[j].alias2, argv[i]) == 0);
+			if (valid)
+				break;
+		}
+
+		if (valid) {
+			switch (options[j].num_args) {
+			case 1:
+				/* ensure there is one, and skip checking next arg */
+				if (i == argc-1) {
+					Sys_Printf ("\n%s: missing arg for option \"%s\"\n",argv[0],argv[i]);
+					exit(1);
+				}
+				/* this assumes that strings beginning with "-" and "+" will
+				 * never be valid values for an option */
+				if (argv[i+1][0] == '-' || argv[i+1][0] == '+') {
+					Sys_Printf ("\n%s: Missing arg for option \"%s\"\n",argv[0],argv[i]);
+					exit(1);
+				}
+				skip = 1;
+				break;
+			case -1:
+				skip = -1;
+				break;
+#if 0
+			case 0:
+				/* doesn't accept args: make sure there aren't any. */
+				if (argv[i+1][0] != '-' && argv[i+1][0] != '+') {
+					Sys_Printf ("\n%s: Unwanted arg for option \"%s\"\n",argv[0],argv[i]);
+					exit(1);
+				}
+#endif
+			}
+		} else {
+			if (argv[i][0] == '+') {
+				skip = -2;
+			} else {
+				Sys_Printf ("\n%s: illegal arg \"%s\"\n", argv[0], argv[i]);
+				exit (1);
+			}
+		}
 	}
-	Sys_PrintTerm ("\n");
 }
 
 /*
@@ -685,23 +888,7 @@ int main (int argc, char **argv)
 
 	PrintVersion();
 
-	if (argc > 1)
-	{
-		for (i = 1; i < argc; i++)
-		{
-			if ( !(strcmp(argv[i], "-v")) || !(strcmp(argv[i], "-version" )) ||
-				!(strcmp(argv[i], "--version")) )
-			{
-				exit(0);
-			}
-			else if ( !(strcmp(argv[i], "-h")) || !(strcmp(argv[i], "-help" )) ||
-				  !(strcmp(argv[i], "-?")) || !(strcmp(argv[i], "--help")) )
-			{
-				PrintHelp(argv[0]);
-				exit (0);
-			}
-		}
-	}
+	CheckArgs(argc, argv);
 
 	/* initialize the host params */
 	memset (&parms, 0, sizeof(parms));