add -u flag, error if variable undefined

builtins.c

@@ -244,6 +244,7 @@ static void b_flag(char **av) {
 		case 's':
 			  if (mode != 2) goto flag_immutable;
 			  flagp = &dashess; break;
+		case 'u': flagp = &dashewe; break;
 		case 'v': flagp = &dashvee; break;
 		case 'x': flagp = &dashex; break;
 	}

glom.c

@@ -420,14 +420,19 @@ extern List *glom(Node *n) {
 			rc_error("multi-word variable name");
 		if (*v->w == '\0')
 			rc_error("zero-length variable name");
+		if (n->type == nCount) {
+		  /*
+		     Allow programmer to get length of undefined variables for idiom: if( ~ $#variable 0) { . . . }
+		  */
+		  v = (*v->w == '*' && v->w[1] == '\0') ? varlookupNonStrict(v->w)->n : varlookupNonStrict(v->w);
+		  return count(v);
+		} 
 		v = (*v->w == '*' && v->w[1] == '\0') ? varlookup(v->w)->n : varlookup(v->w);
 		switch (n->type) {
 		default:
 			panic("unexpected node in glom");
 			exit(1);
 			/* NOTREACHED */
-		case nCount:
-			return count(v);
 		case nFlat:
 			return flatten(v);
 		case nVar:

input.c

@@ -68,9 +68,9 @@ static void history() {
 	List *hist;
 	size_t a;
 
-	if (!interactive || (hist = varlookup("history")) == NULL)
+	if (!interactive || lookup_var("history") == NULL)
 		return;
-
+        hist = varlookup("history");
 	for (a = 0; a < chars_in; a++) {
 		char c = inbuf[a];
 

main.c

@@ -7,7 +7,7 @@
 #include "input.h"
 
 bool dashdee, dashee, dasheye, dashell, dashen;
-bool dashpee, dashoh, dashess, dashvee, dashex;
+bool dashpee, dashoh, dashess, dashvee, dashewe, dashex;
 bool interactive;
 static bool dashEYE;
 char *dashsee[2];
@@ -25,7 +25,7 @@ extern int main(int argc, char *argv[], char *envp[]) {
 	dollarzero = argv[0];
 	rc_pid = getpid();
 	dashell = (*argv[0] == '-'); /* Unix tradition */
-	while ((c = rc_getopt(argc, argv, "c:deiIlnopsvx")) != -1)
+	while ((c = rc_getopt(argc, argv, "c:deiIlnopsuvx")) != -1)
 		switch (c) {
 		case 'c':
 			dashsee[0] = rc_optarg;
@@ -58,6 +58,9 @@ extern int main(int argc, char *argv[], char *envp[]) {
 		case 's':
 			dashess = TRUE;
 			break;
+		case 'u':
+			dashewe = TRUE;
+			break;
 		case 'v':
 			dashvee = TRUE;
 			break;

rc.1

@@ -166,7 +166,7 @@
 rc \- shell
 .SH SYNOPSIS
 .B rc
-.RB [ \-deiIlnopsvx ]
+.RB [ \-deiIlnopsuvx ]
 .RB [ \-c
 .IR command ]
 .RI [ arguments ]
@@ -323,6 +323,11 @@ to read from standard input.
 Any arguments are placed in
 .Cr $* .
 .TP
+.Cr \-u
+This flag causes
+.I rc
+to raise an error if a an undefined variable is used, rather than evaluating it to ().
+.TP
 .Cr \-v
 This flag causes
 .I rc

rc.h

@@ -174,7 +174,7 @@ enum {
 /* main.c */
 extern Rq *redirq;
 extern bool dashdee, dashee, dasheye, dashell, dashen;
-extern bool dashpee, dashoh, dashess, dashvee, dashex;
+extern bool dashpee, dashoh, dashess, dashvee, dashewe, dashex;
 extern bool interactive;
 extern char *dashsee[];
 extern pid_t rc_pid;
@@ -238,6 +238,7 @@ extern Htab *fp, *vp;
 extern void *lookup(char *, Htab *);
 extern rc_Function *get_fn_place(char *);
 extern List *varlookup(char *);
+extern List *varlookupNonStrict(char *);
 extern Node *fnlookup(char *);
 extern Variable *get_var_place(char *, bool);
 extern bool varassign_string(char *);

trip.rc

@@ -1,6 +1,8 @@
 # trip.rc -- take a tour of rc
+# -*-rc-*-
 # Invoke as "path-to-new-rc < trip.rc"
 
+
 rc=$0
 echo tripping $rc $version
 
@@ -411,8 +413,7 @@ if (!~ `{echo '#echo' | $rc -v |[2] sed 's/#//'} echo)
 if (~ `` '' . ?*)
 	fail null dot
 if (~ `` '' {. -i} ?*)
-	fail null dot -i
-
+ 	fail null dot -i
 cat > $tmpdir/dot.$pid << eof
 echo hi
 eof

var.c

@@ -1,5 +1,5 @@
 /* var.c: provide "public" functions for adding and removing variables from the symbol table */
-
+#include <stdio.h>
 #include "rc.h"
 
 #include "input.h"
@@ -52,14 +52,21 @@ extern bool varassign_string(char *extdef) {
 	return TRUE;
 }
 
+char* get_message(char *format, char *msg) {
+    size_t needed = snprintf(NULL, 0, format, msg);
+    char  *buffer = malloc(needed+1);
+    sprintf(buffer, format, msg);
+    return buffer;
+}
+
 /*
    Return a List based on a name lookup. If the list is in external (string) form,
    convert it to internal (List) form. Treat $n (n is an integer) specially as $*(n).
    Also check to see if $status is being dereferenced. (we lazily evaluate the List
    associated with $status)
 */
 
-extern List *varlookup(char *name) {
+List *varlookupAux(char *name, bool strict) {
 	Variable *look;
 	List *ret, *l;
 	int sub;
@@ -79,19 +86,29 @@ extern List *varlookup(char *name) {
 		return ret;
 	}
 	look = lookup_var(name);
-	if (look == NULL)
-		return NULL; /* not found */
+	if (look == NULL) {
+	       if (strict && dashewe)
+		 rc_error(get_message("Undefined variable '%s'\n", name));
+	       return NULL; /* not found */
+	}
 	if (look->def != NULL)
 		return look->def;
 	if (look->extdef == NULL)
 		return NULL; /* variable was set to null, e.g., a=() echo foo */
 	ret = parse_var(look->extdef);
 	if (ret == NULL) {
 		look->extdef = NULL;
+	       if (dashewe) rc_error(get_message("undefined variable '%s'\n", name));
 		return NULL;
 	}
 	return look->def = ret;
 }
+extern List *varlookup(char *name) {
+  return varlookupAux(name, TRUE);
+}
+extern List *varlookupNonStrict(char *name) {
+  return varlookupAux(name, FALSE);
+}
 
 /* lookup a variable in external (string) form, converting if necessary. Used by makeenv() */