Improve debugging features.

* include/smap/wordsplit.h: Rearrange WRDSF_ flags.
(WRDSF_WARNUNDEF): New flag.
(WRDSE_UNDEF): New error code.
* lib/wordsplit.c (expvar): Handle WRDSF_UNDEF and WRDSF_WARNUNDEF.
(wordsplit_perror, _wordsplit_errstr): Handle WRDSE_UNDEF.

* src/cfg.c (parse_config_loop): Level 1 enables WRDSF_WARNUNDEF.

* doc/debugcat.texi: Document level conf(5).

4 files changed, 67 insertions, 35 deletions

diff --git a/doc/debugcat.texi b/doc/debugcat.texi
index 5bafb84..7bb9023 100644
--- a/doc/debugcat.texi
+++ b/doc/debugcat.texi
@@ -40,3 +40,16 @@ Databases and their functionality.
 @item query (4)
-Query routing.
+Query dispatcher.
+
+@item conf (5)
+Configuration file parser.
+
+Level @samp{1} enables warnings about undefined variables.
+
+Level @samp{2} displays each logical line and the result of
+expanding and splitting it.
+
+Level @samp{100} enables wordsplitter debugging.  This means a
+@emph{lot} of cryptic output useful only to those who have a
+good knowledge of how the wordsplitter works.
+
 @end table
diff --git a/include/smap/wordsplit.h b/include/smap/wordsplit.h
index 07afc0a..de3a697 100644
--- a/include/smap/wordsplit.h
+++ b/include/smap/wordsplit.h
@@ -46,8 +46,8 @@ struct wordsplit
    call. */
-#define WRDSF_APPEND            0x000001
+#define WRDSF_APPEND            0x0000001
 /* Insert we_offs initial NULLs in the array ws_wordv.
    (These are not counted in the returned ws_wordc.) */
-#define WRDSF_DOOFFS            0x000002
+#define WRDSF_DOOFFS            0x0000002
 /* Don't do command substitution. Reserved for future use. */
-#define WRDSF_NOCMD             0x000004
+#define WRDSF_NOCMD             0x0000004
 /* The parameter p resulted from a previous call to
@@ -55,47 +55,49 @@ struct wordsplit
    allocated storage. */
-#define WRDSF_REUSE             0x000008
+#define WRDSF_REUSE             0x0000008
 /* Print errors */
-#define WRDSF_SHOWERR           0x000010
+#define WRDSF_SHOWERR           0x0000010
 /* Consider it an error if an undefined shell variable
    is expanded. */
-#define WRDSF_UNDEF             0x000020
+#define WRDSF_UNDEF             0x0000020
 
 /* Don't do variable expansion. Reserved for future use. */
-#define WRDSF_NOVAR             0x000040
+#define WRDSF_NOVAR             0x0000040
 /* Abort on ENOMEM error */
-#define WRDSF_ENOMEMABRT        0x000080
+#define WRDSF_ENOMEMABRT        0x0000080
 /* Treat whitespace as delimiters */
-#define WRDSF_WS                0x000100
+#define WRDSF_WS                0x0000100
 /* Handle quotes and escape directives */
-#define WRDSF_QUOTE             0x000200
+#define WRDSF_QUOTE             0x0000200
 /* Replace each input sequence of repeated delimiters with a single
    delimiter */
-#define WRDSF_SQUEEZE_DELIMS    0x000400
+#define WRDSF_SQUEEZE_DELIMS    0x0000400
 /* Return delimiters */
-#define WRDSF_RETURN_DELIMS     0x000800
+#define WRDSF_RETURN_DELIMS     0x0000800
 /* Treat sed expressions as words */
-#define WRDSF_SED_EXPR          0x001000
+#define WRDSF_SED_EXPR          0x0001000
 /* ws_delim field is initialized */
-#define WRDSF_DELIM             0x002000
+#define WRDSF_DELIM             0x0002000
 /* ws_comment field is initialized */
-#define WRDSF_COMMENT           0x004000
+#define WRDSF_COMMENT           0x0004000
 /* ws_alloc_die field is initialized */
-#define WRDSF_ALLOC_DIE         0x008000
+#define WRDSF_ALLOC_DIE         0x0008000
 /* ws_error field is initialized */
-#define WRDSF_ERROR             0x010000
+#define WRDSF_ERROR             0x0010000
+/* ws_debug field is initialized */
+#define WRDSF_DEBUG             0x0020000
 /* ws_env field is initialized */
-#define WRDSF_ENV               0x020000
+#define WRDSF_ENV               0x0040000
 /* ws_getvar field is initialized */
-#define WRDSF_GETVAR            0x040000
+#define WRDSF_GETVAR            0x0080000
 /* enable debugging */
-#define WRDSF_SHOWDBG           0x080000
+#define WRDSF_SHOWDBG           0x0100000
 /* Don't split input into words.  Useful for side effects. */
-#define WRDSF_NOSPLIT           0x100000
+#define WRDSF_NOSPLIT           0x0200000
 /* Keep undefined variables in place, instead of expanding them to
    empty string */
-#define WRDSF_KEEPUNDEF         0x200000
+#define WRDSF_KEEPUNDEF         0x0400000
+/* Warn about undefined variables */
+#define WRDSF_WARNUNDEF         0x0800000
 /* Handle C escapes */
-#define WRDSF_CESCAPES          0x400000
-/* ws_debug field is initialized */
-#define WRDSF_DEBUG             0x800000
+#define WRDSF_CESCAPES          0x1000000
 
@@ -111,2 +113,3 @@ struct wordsplit
 #define WRDSE_CBRACE     5
+#define WRDSE_UNDEF      6
 
diff --git a/lib/wordsplit.c b/lib/wordsplit.c
index 9f1b9d5..d1851bf 100644
--- a/lib/wordsplit.c
+++ b/lib/wordsplit.c
@@ -671,6 +671,16 @@ expvar(struct wordsplit *wsp, const char *str, size_t len,
 		value = wsp->ws_getvar(str, i);
-	else if (wsp->ws_flags & WRDSF_KEEPUNDEF)
-		value = NULL;
-	else
-		value = "";
+	else if (wsp->ws_flags & WRDSF_UNDEF) {
+		wsp->ws_errno = WRDSE_UNDEF;
+		if (wsp->ws_flags & WRDSF_SHOWERR)
+			wordsplit_perror(wsp);
+		return 1;
+	} else {
+		if (wsp->ws_flags & WRDSF_WARNUNDEF)
+			wsp->ws_error(_("warning: undefined variable `%.*s'"),
+				      i, str);
+		if (wsp->ws_flags & WRDSF_KEEPUNDEF)
+			value = NULL;
+		else
+			value = "";
+	}
 	 /* FIXME: handle defstr */
@@ -1223,4 +1233,3 @@ wordsplit_perror(struct wordsplit *wsp)
 	case WRDSE_NOSUPP:
-		wsp->ws_error(_("command substitution "
-				"is not yet supported"));
+		wsp->ws_error(_("command substitution is not yet supported"));
 
@@ -1233,2 +1242,6 @@ wordsplit_perror(struct wordsplit *wsp)
 		break;
+
+	case WRDSE_UNDEF:
+		wsp->ws_error(_("undefined variable"));
+		break;
 		
@@ -1246,3 +1259,4 @@ const char *_wordsplit_errstr[] = {
 	N_("invalid wordsplit usage"),
-	N_("unbalanced curly brace")
+	N_("unbalanced curly brace"),
+	N_("undefined variable")
 };
diff --git a/src/cfg.c b/src/cfg.c
index b0efe1c..ca61ab4 100644
--- a/src/cfg.c
+++ b/src/cfg.c
@@ -280,3 +280,5 @@ parse_config_loop(struct cfg_kw *kwtab, void *data)
 	ws.ws_comment = "#";
-	
+
+	if (smap_debug_np(DBG_CONF, 1))
+		wsflags |= WRDSF_WARNUNDEF;
 	if (smap_debug_np(DBG_CONF, 100)) {
@@ -300,3 +302,3 @@ parse_config_loop(struct cfg_kw *kwtab, void *data)
 
-		if (smap_debug_np(DBG_CONF, 1)) {
+		if (smap_debug_np(DBG_CONF, 2)) {
 			size_t i;