Fix kern/187712: config(8) does not respect KERNCONFDIR.

The impact of this bug is that you cannot build a kernel if both of the
following are true:
1) The kernel config file is in a non-default location
2) The kernel config file uses the "include" statement from config(5).

usr.sbin/config/main.c
usr.sbin/config/config.8
usr.sbin/config/config.h
usr.sbin/config/lang.l
	Added a "-I path" option to config(8).  By analogy to cc(1), it adds
	an extra path in which the "include" statement will search for
	files.

Makefile.inc1
	Pass "-I ${KERNCONFDIR}" to config(8).

PR:		kern/187712
Reviewed by:	will, imp (previous version)
MFC after:	3 weeks
Sponsored by:	Spectra Logic Corporation

Makefile.inc1

@@ -1015,7 +1015,7 @@ buildkernel:
 	cd ${KRNLCONFDIR}; \
 		PATH=${TMPPATH} \
 		    config ${CONFIGARGS} -d ${KRNLOBJDIR}/${_kernel} \
-			${KERNCONFDIR}/${_kernel}
+			-I ${KERNCONFDIR} ${KERNCONFDIR}/${_kernel}
 .endif
 .if !defined(NO_CLEAN) && !defined(NO_KERNELCLEAN)
 	@echo

usr.sbin/config/config.8

@@ -37,6 +37,7 @@
 .Sh SYNOPSIS
 .Nm
 .Op Fl CVgp
+.Op Fl I Ar path
 .Op Fl d Ar destdir
 .Ar SYSTEM_NAME
 .Nm
@@ -69,6 +70,12 @@ If the INCLUDE_CONFIG_FILE is present in a configuration file,
 kernel image will contain full configuration files included
 literally (preserving comments).
 This flag is kept for backward compatibility.
+.It Fl I Ar path
+Search in
+.Ar path
+for any file included by the 
+.Ic include
+directive.  This option may be specified more than once.
 .It Fl d Ar destdir
 Use
 .Ar destdir

usr.sbin/config/config.h

@@ -144,6 +144,13 @@ struct hint {
 
 STAILQ_HEAD(hint_head, hint) hints;
 
+struct includepath {
+	char	*path;
+	SLIST_ENTRY(includepath) path_next;
+};
+
+SLIST_HEAD(, includepath) includepath;
+
 /*
  * Tag present in the kernelconf.tmlp template file. It's mandatory for those
  * two strings to be the same. Otherwise you'll get into trouble.

usr.sbin/config/lang.l

@@ -34,6 +34,7 @@
 #include <assert.h>
 #include <ctype.h>
 #include <err.h>
+#include <stdlib.h>
 #include <string.h>
 #include "y.tab.h"
 #include "config.h"
@@ -257,6 +258,7 @@ include(const char *fname, int ateof)
 {
 	FILE *fp;
 	struct incl *in;
+	struct includepath* ipath;
 	char *fnamebuf;
 
 	fnamebuf = NULL;
@@ -268,6 +270,17 @@ include(const char *fname, int ateof)
 			free(fnamebuf);
 		}
 	}
+	if (fp == NULL) {
+		SLIST_FOREACH(ipath, &includepath, path_next) {
+			asprintf(&fnamebuf, "%s/%s", ipath->path, fname);
+			if (fnamebuf != NULL) {
+				fp = fopen(fnamebuf, "r");
+				free(fnamebuf);
+			}
+			if (fp != NULL)
+				break;
+		}
+	}
 	if (fp == NULL) {
 		yyerror("cannot open included file");
 		return (-1);

usr.sbin/config/main.c

@@ -110,15 +110,25 @@ main(int argc, char **argv)
 	int ch, len;
 	char *p;
 	char *kernfile;
+	struct includepath* ipath;
 	int printmachine;
 
 	printmachine = 0;
 	kernfile = NULL;
-	while ((ch = getopt(argc, argv, "Cd:gmpVx:")) != -1)
+	SLIST_INIT(&includepath);
+	while ((ch = getopt(argc, argv, "CI:d:gmpVx:")) != -1)
 		switch (ch) {
 		case 'C':
 			filebased = 1;
 			break;
+		case 'I':
+			ipath = (struct includepath *) \
+			    	calloc(1, sizeof (struct includepath));
+			if (ipath == NULL)
+				err(EXIT_FAILURE, "calloc");
+			ipath->path = optarg;
+			SLIST_INSERT_HEAD(&includepath, ipath, path_next);
+			break;
 		case 'm':
 			printmachine = 1;
 			break;