Introduce 'function' built-in

As requested in #4, here's my proposal. This is a wrapper around goto and source. The script recurses itself and searches for a goto label. It's an error for labels not contain an exit to their end. Function calls outside labels are, by default, labeled main.

This was tested sparsely, and may contain bugs I haven't faced, but is working as expected. One bug to be noted is that pipes don't give up on errors. This is possibly due to forking.

I noticed Tcsh has a built-in function command, but I can't trace the code. Said built-in function command is evaluated before mine, thus those who attempt to execute it won't get the correct error message.

sh.c

@@ -111,6 +111,7 @@ int	exitset = 0;
 static time_t  chktim;		/* Time mail last checked */
 char *progname;
 int tcsh;
+struct funcargs *fargv = NULL;
 
 /*
  * This preserves the input state of the shell. It is used by
@@ -1993,6 +1994,59 @@ process(int catch)
 
     getexit(osetexit);
     omark = cleanup_push_mark();
+
+    /* If this is a function, setup STRargv and invoke goto. */
+    if (fargv) {
+	int funcdelim = 0;
+	Char funcexit[] = { 'e', 'x', 'i', 't', 0 },
+	     funcmain[] = { 'm', 'a', 'i', 'n', 0 };
+	struct Strbuf aword = Strbuf_INIT;
+	cleanup_push(&aword, Strbuf_cleanup);
+	Sgoal = funcmain;
+	Stype = TC_GOTO;
+
+	if (!fargv->prev)
+	    while (!funcdelim) {
+		(void) getword(&aword);
+		Strbuf_terminate(&aword);
+
+		if (aword.s[0] != ':' && lastchr(aword.s) == ':')
+		    funcerror(funcmain, funcexit);
+		else if (eq(aword.s, funcexit))
+		    funcdelim = 1;
+
+		(void) getword(NULL);
+	    }
+
+	setq(STRargv, &fargv->v[3], &shvhed, 0);
+	dogoto(&fargv->v[1], fargv->t);
+
+	{
+	    struct Ain a;
+
+	    cleanup_push(&aword, Strbuf_cleanup);
+	    Sgoal = fargv->v[2];
+	    Stype = TC_EXIT;
+	    a.type = TCSH_F_SEEK;
+	    btell(&a);
+	    funcdelim = 0;
+
+	    while (!funcdelim) {
+		(void) getword(&aword);
+		Strbuf_terminate(&aword);
+
+		if (aword.s[0] != ':' && lastchr(aword.s) == ':')
+		    funcerror(fargv->v[2], funcexit);
+		else if (eq(aword.s, funcexit))
+		    funcdelim = 1;
+
+		(void) getword(NULL);
+	    }
+
+	    bseek(&a);
+	}
+    }
+
     for (;;) {
 	struct command *t;
 	int hadhist, old_pintr_disabled;
@@ -2177,6 +2231,20 @@ process(int catch)
 	else
 	    haderr = 1;
     }
+
+    if (fargv) {
+	/* Reset STRargv on function exit. */
+	setv(STRargv, NULL, 0);
+
+	if (fargv->prev)
+	{
+	    fargv = fargv->prev;
+	    free(fargv->next);
+	}
+	else
+	    free(fargv);
+    }
+
     cleanup_pop_mark(omark);
     resexit(osetexit);
     exitset--;

sh.decls.h

@@ -105,6 +105,7 @@ extern	void		  xfree_indirect(void *);
 extern	void		  errinit	(void);
 extern	void		  seterror	(unsigned int, ...);
 extern	void		  fixerror	(void);
+extern	void		  funcerror	(Char *, Char *);
 extern	void		  stderror	(unsigned int, ...)
     __attribute__((__noreturn__));
 
@@ -150,6 +151,7 @@ extern	void		  doend		(Char **, struct command *);
 extern	void		  doeval	(Char **, struct command *);
 extern	void		  doexit	(Char **, struct command *);
 extern	void		  doforeach	(Char **, struct command *);
+extern	void		  dofunction	(Char **, struct command *);
 extern	void		  doglob	(Char **, struct command *);
 extern	void		  dogoto	(Char **, struct command *);
 extern	void		  doif		(Char **, struct command *);

sh.err.c

@@ -187,7 +187,8 @@ extern int enterhist;
 #define ERR_INVALID	133
 #define ERR_BADCOLORVAR	134
 #define ERR_EOF		135
-#define NO_ERRORS	136
+#define ERR_DOLFUNC	136
+#define NO_ERRORS	137
 
 static const char *elst[NO_ERRORS] INIT_ZERO_STRUCT;
 
@@ -365,6 +366,7 @@ errinit(void)
     elst[ERR_BADJOB] = CSAVS(1, 136, "No such job (badjob)");
     elst[ERR_BADCOLORVAR] = CSAVS(1, 137, "Unknown colorls variable '%c%c'");
     elst[ERR_EOF] = CSAVS(1, 138, "Unexpected end of file");
+    elst[ERR_DOLFUNC] = CSAVS(1, 139, "Functions are only supported for scripts");
 }
 
 /* Cleanup data. */
@@ -654,3 +656,16 @@ stderror(unsigned int id, ...)
 
     reset();		/* Unwind */
 }
+
+void
+funcerror(Char *n, Char *msg)
+{
+    char nconv[Strlen(n) + 1],
+	 msgconv[Strlen(msg) + 1];
+
+    strcpy(nconv, short2str(n));
+    strcpy(msgconv, short2str(msg));
+
+    setname(nconv);
+    stderror(ERR_NAME | ERR_NOTFOUND, msgconv);
+}

sh.func.c

@@ -56,7 +56,6 @@ static	void	preread		(void);
 static	void	doagain		(void);
 static  const char *isrchx	(int);
 static	void	search		(int, int, Char *);
-static	int	getword		(struct Strbuf *);
 static	struct wordent	*histgetword	(struct wordent *);
 static	void	toend		(void);
 static	void	xecho		(int, Char **);
@@ -742,8 +741,8 @@ isrchx(int n)
 }
 
 
-static int Stype;
-static Char *Sgoal;
+int Stype;
+Char *Sgoal;
 
 static void
 search(int type, int level, Char *goal)
@@ -1000,7 +999,7 @@ histgetword(struct wordent *histent)
     return NULL;
 }
 
-static int
+int
 getword(struct Strbuf *wp)
 {
     int found = 0, first;
@@ -1096,6 +1095,11 @@ getword(struct Strbuf *wp)
 	stderror(ERR_NAME | ERR_NOTFOUND, "label");
 	break;
 
+    case TC_EXIT:
+	setname(short2str(Sgoal));
+	stderror(ERR_NAME | ERR_NOTFOUND, "exit");
+	break;
+
     default:
 	break;
     }
@@ -2694,3 +2698,41 @@ getYN(const char *prompt)
 	continue;
     return doit;
 }
+
+void
+dofunction(Char **v, struct command *t)
+{
+    if (!ffile)
+	stderror(ERR_DOLFUNC);
+
+    {
+	int i, j;
+	Char **vh;
+
+	for (i = 0; v[i]; i++)
+	    ;
+
+	vh = xmalloc((i + 2) * sizeof(Char *));
+	vh[i + 1] = NULL;
+
+	for (j = i--; i; i--, j--) {
+	    vh[j] = xmalloc(((Strlen(v[i]) + 1) * sizeof(Char)));
+	    Strcpy(vh[j], v[i]);
+	}
+	vh[1] = xmalloc(Strlen(ffile) + 1);
+	Strcpy(vh[1], ffile);
+	*vh = xmalloc(Strlen(*v) + 1);
+	Strcpy(*vh, *v);
+
+	if (fargv) {
+	    fargv->next = malloc(sizeof *fargv);
+	    fargv->next->prev = fargv;
+	    fargv = fargv->next;
+	} else {
+	    fargv = malloc(sizeof *fargv);
+	    fargv->prev = NULL;
+	}
+
+	dosource(fargv->v = vh, fargv->t = t);
+    }
+}

sh.h

@@ -1302,5 +1302,15 @@ extern int    filec;
 #define TEXP_IGNORE 1	/* in ignore, it means to ignore value, just parse */
 #define TEXP_NOGLOB 2	/* in ignore, it means not to globone */
 
+/* Function variable(s) and function(s). */
+extern Char *Sgoal;
+extern int Stype;
+extern struct funcargs {
+    Char **v;
+    struct command *t;
+    struct funcargs *prev,
+		    *next;
+} *fargv;
+extern int getword(struct Strbuf *);
 
 #endif /* _h_sh */

sh.init.c

@@ -80,6 +80,7 @@ const struct biltins bfunc[] = {
     { "fg",		dofg,		0,	INF	},
     { "filetest",	dofiletest,	2,	INF	},
     { "foreach",	doforeach,	3,	INF	},
+    { "function",	dofunction,	1,	INF	},
 #ifdef TCF
     { "getspath",	dogetspath,	0,	0	},
     { "getxvers",	dogetxvers,	0,	0	},