Add support for "ifdef <attribute>" blocks. It goes like this:

ifdef <attr> / ifndef <attr>
elifdef <attr>
elifndef <attr>
else
endif

No indentation is possible for now, it will come later.

usr.bin/config/config.5

@@ -1,4 +1,4 @@
-.\" $NetBSD: config.5,v 1.11 2007/09/10 10:54:20 cube Exp $
+.\" $NetBSD: config.5,v 1.12 2007/11/09 23:41:08 cube Exp $
 .\"
 .\"  Copyright (c) 2006, 2007 The NetBSD Foundation.
 .\"  All rights reserved.
@@ -27,7 +27,7 @@
 .\"  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 .\"  POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd January 9, 2007
+.Dd November 9, 2007
 .Dt CONFIG 5
 .Os
 .Sh NAME
@@ -268,6 +268,19 @@ The
 .Ar path
 argument is either absolute or relative to the current defined prefix, which
 defaults to the top of ther kernel source tree.
+.It Ic ifdef Ar attribute
+.It Ic ifndef Ar attribute
+.It Ic elifdef Ar attribute
+.It Ic elifndef Ar attribute
+.It Ic else
+.It Ic endif
+Conditionally interprets portions of the current file.
+Those statements depend on whether or not the given
+.Ar attribute
+has been previously defined, through
+.Ic define
+or any other statement that implicitely defines attributes such as
+.Ic device .
 .El
 .Ss PREAMBLE
 In addition to

usr.bin/config/defs.h

@@ -1,4 +1,4 @@
-/*	$NetBSD: defs.h,v 1.20 2007/01/13 23:47:36 christos Exp $	*/
+/*	$NetBSD: defs.h,v 1.21 2007/11/09 23:41:08 cube Exp $	*/
 
 /*
  * Copyright (c) 1992, 1993
@@ -98,7 +98,7 @@ extern const char *progname;
  * The next two lines define the current version of the config(1) binary,
  * and the minimum version of the configuration files it supports.
  */
-#define CONFIG_VERSION		20070109
+#define CONFIG_VERSION		20071109
 #define CONFIG_MINVERSION	0
 
 /*

usr.bin/config/scan.l

@@ -1,5 +1,5 @@
 %{
-/*	$NetBSD: scan.l,v 1.8 2007/11/09 05:06:08 cube Exp $	*/
+/*	$NetBSD: scan.l,v 1.9 2007/11/09 23:41:08 cube Exp $	*/
 
 /*
  * Copyright (c) 1992, 1993
@@ -59,6 +59,34 @@ int	yyline;
 const char *yyfile;
 const char *lastfile;
 char curinclpath[PATH_MAX];
+int ifdefstate = -1;
+int st;
+#define IDS_PARENT_DISABLED \
+    ((ifdefstate > 6) && ((((ifdefstate/6)-1) & 1) == 1))
+#define IDS_MAX_DEPTH		362797056 /* 6^11 */
+/* States for ifdefstate:
+
+  0  -> matched ifdef
+  1  -> unmatched ifdef
+  2  -> matched elifdef
+  3  -> unmatched elifdef
+  4  -> matched else
+  5  -> unmatched else
+
+  Upon "ifdef", add one and multiply by 6.
+  Upon "endif", divide by 6, remove 1.
+
+  ifdef -> MATCH => continue
+           MISMATCH => set to 1
+  elifdef -> if (!1) -> MISMATCH
+             MATCH => set to 2
+             MISMATCH => if (2 || 3) set to 3, else set to 1
+  else -> if (1) -> MATCH
+          MATCH => set to 4
+          MISMATCH => set to 5
+
+  in each case, if parent & 1 == 1, MISMATCH
+*/
  
 /*
  * Data for returning to previous files from include files.
@@ -70,10 +98,12 @@ struct incl {
 	int	in_lineno;	/* previous line number */
 	int	in_ateof;	/* token to insert at EOF */
 	int	in_interesting;	/* previous value for "interesting" */
+	int	in_ifdefstate;	/* conditional level */
 };
 static struct incl *incl;
 static int endinclude(void);
 static int getincludepath(void);
+static int getcurifdef(void);
 
 #define	yywrap() 1
 
@@ -85,6 +115,8 @@ WORD	[A-Za-z_][-A-Za-z_0-9]*
 FILENAME	({PATH}|\"{QCHARS}\")
 RESTOFLINE	[ \t]*(#[^\n]*)?\n
 
+%x	IGNORED
+
 %%
 		/* Local variables for yylex() */
 		int tok;
@@ -135,6 +167,107 @@ with		return WITH;
 \+=		return PLUSEQ;
 :=		return COLONEQ;
 
+<*>ifdef[ \t]+{WORD}{RESTOFLINE} {
+		ifdefstate = (ifdefstate + 1) * 6;
+		if (ifdefstate >= IDS_MAX_DEPTH) {
+			yyerror("too many levels of conditional");
+		}
+		if (!IDS_PARENT_DISABLED && getcurifdef()) {
+			BEGIN(INITIAL);
+		} else {
+			ifdefstate++;
+			BEGIN(IGNORED);
+		}
+		yyline++;
+	}
+
+<*>ifndef[ \t]+{WORD}{RESTOFLINE} {
+		ifdefstate = (ifdefstate + 1) * 6;
+		if (ifdefstate >= IDS_MAX_DEPTH) {
+			yyerror("too many levels of conditional");
+		}
+		if (!IDS_PARENT_DISABLED && !getcurifdef()) {
+			BEGIN(INITIAL);
+		} else {
+			ifdefstate++;
+			BEGIN(IGNORED);
+		}
+		yyline++;
+	}
+
+
+<*>elifdef[ \t]+{WORD}{RESTOFLINE} {
+		st = ifdefstate % 6;
+		if (ifdefstate < 0 || st > 3) {
+			yyerror("mismatched elifdef");
+		}
+		if (IDS_PARENT_DISABLED ||
+		    st != 1 || !getcurifdef()) {
+			if (st == 2 || st == 3) {
+				ifdefstate += 3 - st;
+			} else {
+				ifdefstate += 1 - st;
+			}
+			BEGIN(IGNORED);
+		} else {
+			ifdefstate++;
+			BEGIN(INITIAL);
+		}
+		yyline++;
+	}
+
+<*>elifndef[ \t]+{WORD}{RESTOFLINE} {
+		st = ifdefstate % 6;
+		if (ifdefstate < 0 || st > 3) {
+			yyerror("mismatched elifndef");
+		}
+		if (IDS_PARENT_DISABLED ||
+		    st != 1 || getcurifdef()) {
+			if (st == 2 || st == 3) {
+				ifdefstate += 3 - st;
+			} else {
+				ifdefstate += 1 - st;
+			}
+			BEGIN(IGNORED);
+		} else {
+			ifdefstate++;
+			BEGIN(INITIAL);
+		}
+		yyline++;
+	}
+
+<*>else{RESTOFLINE} {
+		st = ifdefstate % 6;
+		if (ifdefstate < 0 || st > 3) {
+			yyerror("mismatched else");
+		}
+		if (!IDS_PARENT_DISABLED && (st == 1)) {
+			ifdefstate += 3;
+			BEGIN(INITIAL);
+		} else {
+			ifdefstate += 5 - st;
+			BEGIN(IGNORED);
+		}
+		yyline++;
+	}
+
+<*>endif{RESTOFLINE} {
+		if (ifdefstate < 0) {
+			yyerror("mismatched endif");
+		}
+		if (!IDS_PARENT_DISABLED) {
+			BEGIN(INITIAL);
+		}
+		ifdefstate = (ifdefstate/6) - 1;
+		yyline++;
+	}
+
+<IGNORED>\n		{
+		yyline++;
+	}
+
+<IGNORED>.	/* ignore */
+
 include[ \t]+{FILENAME}{RESTOFLINE}	{
 		yyline++;
 		if (getincludepath()) {
@@ -224,7 +357,10 @@ package[ \t]+{FILENAME}{RESTOFLINE}	{
 #.*	{ /* ignored (comment) */; }
 [ \t]+	{ /* ignored (white space) */; }
 .	{ return yytext[0]; }
-<<EOF>> {
+<*><<EOF>> {
+		if (ifdefstate > (incl == NULL ? -1 : incl->in_ifdefstate)) {
+			yyerror("reached EOF while looking for endif");
+		}
 		if (incl == NULL)
 			return YY_NULL;
 		tok = endinclude();
@@ -380,6 +516,7 @@ include(const char *fname, int ateof, int conditional, int direct)
 	in->in_lineno = yyline;
 	in->in_ateof = ateof;
 	in->in_interesting = interesting;
+	in->in_ifdefstate = ifdefstate;
 	interesting = direct & interesting;
 	if (interesting)
 		logconfig_include(fp, fname);
@@ -465,3 +602,20 @@ currentline(void)
 
 	return (yyline - (yychar == '\n'));
 }
+
+static int
+getcurifdef(void)
+{
+	char *p = yytext, *q;
+
+	while (*p && isascii((unsigned int)*p) && !isspace((unsigned int)*p))
+		p++;
+	while (*p && isascii((unsigned int)*p) && isspace((unsigned int)*p))
+		p++;
+	q = p;
+	while (*q && isascii((unsigned int)*q) && !isspace((unsigned int)*q))
+		q++;
+	*q = '\0';
+
+	return ht_lookup(attrtab, intern(p)) != NULL;
+}