From c27a50568cf407ce8faea4adcc3e07756c002c8a Mon Sep 17 00:00:00 2001
From: midipix <writeonce@midipix.org>
Date: Jun 09 2018 00:48:12 +0000
Subject: driver: support cmd selection via symlinks and/or program name.


---

diff --git a/include/ntux/ntux.h b/include/ntux/ntux.h
index ff7d504..6063304 100644
--- a/include/ntux/ntux.h
+++ b/include/ntux/ntux.h
@@ -54,6 +54,7 @@ enum ntux_cmd {
 	NTUX_CMD_STAT,
 	NTUX_CMD_SPAWN,
 	NTUX_CMD_STRACE,
+	NTUX_CMD_CAP,
 };
 
 struct ntux_source_version {
diff --git a/src/driver/ntux_driver_ctx.c b/src/driver/ntux_driver_ctx.c
index f06d085..cc5142b 100644
--- a/src/driver/ntux_driver_ctx.c
+++ b/src/driver/ntux_driver_ctx.c
@@ -29,6 +29,21 @@ static const nt_tty_affiliation tty_affiliation
 /* ntapi accessor table */
 const ntapi_vtbl * ntux_ntapi;
 
+/* ntux command names */
+static const char * const ntux_cmd_name[NTUX_CMD_CAP] = {
+	[NTUX_CMD_STAT]       = "stat",
+	[NTUX_CMD_SPAWN]      = "spawn",
+	[NTUX_CMD_STRACE]     = "strace",
+};
+
+/* ntux command options */
+static const struct argv_option * ntux_cmd_options[NTUX_CMD_CAP] = {
+	[NTUX_CMD_DEFAULT]    = ntux_default_options,
+	[NTUX_CMD_STAT]       = ntux_default_options,
+	[NTUX_CMD_SPAWN]      = ntux_spawn_options,
+	[NTUX_CMD_STRACE]     = ntux_strace_options,
+};
+
 /* package info */
 static const struct ntux_source_version ntux_src_version = {
 	NTUX_TAG_VER_MAJOR,
@@ -64,9 +79,22 @@ static int ntux_driver_usage(
 	const char *			program,
 	const char *			arg,
 	const struct argv_option **	optv,
-	struct argv_meta *		meta)
+	struct argv_meta *		meta,
+	enum ntux_cmd			cmd)
 {
-	char header[512];
+	char		header[512];
+	char *		cmdarg[2];
+	const char *	cmdname;
+
+	if (cmd == NTUX_CMD_DEFAULT) {
+		cmdarg[0] = "";
+		cmdarg[1] = "";
+		cmdname   = "";
+	} else {
+		cmdarg[0] = " (--cmd=";
+		cmdarg[1] = ")";
+		cmdname   = ntux_cmd_name[cmd];
+	}
 
 	snprintf(header,sizeof(header),
 		"Usage: %s [options] ...\n"
@@ -76,8 +104,8 @@ static int ntux_driver_usage(
 		"       for commands that spawn other programs (e.g. spawn, strace),\n"
 		"       the first non-option argument must specify the name of the\n"
 		"       program to be executed.\n\n"
-		"Options:\n",
-		program,program);
+		"Options%s%s%s:\n",
+		program,program,cmdarg[0],cmdname,cmdarg[1]);
 
 	argv_usage(stdout,header,optv,arg);
 	argv_free(meta);
@@ -140,7 +168,7 @@ static int ntux_cctx_update(
 					if (flags & NTUX_DRIVER_VERBOSITY_USAGE)
 						return ntux_driver_usage(
 							program,entry->arg,
-							optv,0);
+							optv,0,cctx->cmd);
 
 				case TAG_VERSION:
 					cctx->drvflags |= NTUX_DRIVER_VERSION;
@@ -150,7 +178,7 @@ static int ntux_cctx_update(
 					if (*nunits)
 						return ntux_driver_usage(
 							program,entry->arg,
-							optv,0);
+							optv,0,cctx->cmd);
 
 					if (!strcmp(entry->arg,"stat"))
 						cctx->cmd = NTUX_CMD_STAT;
@@ -185,6 +213,32 @@ static int ntux_get_driver_ctx_fail(struct argv_meta * meta)
 	return -1;
 }
 
+static int ntux_cmd_from_program(const char * program)
+{
+	const char *	dot;
+	const char *	hyphen;
+	const char *	mark;
+
+	dot    = strrchr(program,'.');
+	hyphen = strrchr(program,'-');
+
+	if (hyphen > dot)
+		mark = ++hyphen;
+	else if (dot > hyphen)
+		mark = ++dot;
+	else
+		mark = program;
+
+	if (!strcmp(mark,"stat"))
+		return NTUX_CMD_STAT;
+	else if (!strcmp(mark,"spawn"))
+		return NTUX_CMD_SPAWN;
+	else if (!strcmp(mark,"strace"))
+		return NTUX_CMD_STRACE;
+
+	return NTUX_CMD_DEFAULT;
+}
+
 int ntux_get_driver_ctx(
 	char **				argv,
 	char **				envp,
@@ -212,16 +266,17 @@ int ntux_get_driver_ctx(
 
 	memset(&cctx,0,sizeof(cctx));
 
-	cctx.drvflags = flags;
-	program       = argv_program_name(argv[0]);
 	nunits	      = 0;
 	execargv      = 0;
+	program       = argv_program_name(argv[0]);
+	cctx.cmd      = ntux_cmd_from_program(program);
+	cctx.drvflags = flags;
 
 	/* missing arguments? */
-	argv_optv_init(ntux_default_options,optv);
+	argv_optv_init(ntux_cmd_options[cctx.cmd],optv);
 
 	if (!argv[1] && (flags & NTUX_DRIVER_VERBOSITY_USAGE))
-		return ntux_driver_usage(program,0,optv,0);
+		return ntux_driver_usage(program,0,optv,0,cctx.cmd);
 
 	/* initial argv scan: ... --cmd=xxx ... */
 	for (parg=argv, cmdargv=0; *parg && !cmdargv; parg++) {
@@ -271,7 +326,7 @@ int ntux_get_driver_ctx(
 		}
 
 		if (!ctx.unitidx && (flags & NTUX_DRIVER_VERBOSITY_USAGE))
-			ntux_driver_usage(program,0,optv,0);
+			ntux_driver_usage(program,0,optv,0,cctx.cmd);
 
 		if (!ctx.unitidx)
 			return NTUX_ERROR;
@@ -300,7 +355,7 @@ int ntux_get_driver_ctx(
 
 	/* finalize */
 	if (nunits && !cctx.cmd)
-		return ntux_driver_usage(program,0,optv,meta);
+		return ntux_driver_usage(program,0,optv,meta,NTUX_CMD_DEFAULT);
 
 	if (!(ictx = ntux_driver_ctx_alloc(meta,&cctx,nunits)))
 		return ntux_get_driver_ctx_fail(meta);