fix a seg and minor improvements to config(8)

[Edd Barrett]

Evening,

When using `config -e`:
 * Don't print a NULL pointer if binary loaded is not a kernel.
 * Don't segfault of binary loaded is not a kernel.
 * Report non-existent kernel via a preliminary stat().
 * Make a warning look like the rest.

 OK?

Index: exec.c
===================================================================
RCS file: /cvs/src/usr.sbin/config/exec.c,v
retrieving revision 1.7
diff -u -r1.7 exec.c
--- exec.c      27 Oct 2009 23:59:51 -0000      1.7
+++ exec.c      28 Sep 2011 01:19:49 -0000
@@ -26,6 +26,8 @@
 
 #include <err.h>
 #include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
 #include <stdio.h>
 
 #ifdef AOUT_SUPPORT
@@ -109,6 +111,11 @@
 void
 loadkernel(char *file)
 {
+       struct stat                     st;
+
+       if (stat(file, &st) == -1)
+               err(1, "cannot stat '%s'", file);
+
        current_exec = -1;
 
 #ifdef AOUT_SUPPORT
Index: ukc.c
===================================================================
RCS file: /cvs/src/usr.sbin/config/ukc.c,v
retrieving revision 1.16
diff -u -r1.16 ukc.c
--- ukc.c       10 Dec 2009 22:07:19 -0000      1.16
+++ ukc.c       28 Sep 2011 01:19:49 -0000
@@ -114,10 +114,8 @@
                }
        }
 
-       printf("%s", adjust((caddr_t)nl[P_VERSION].n_value));
-
        if (force == 0 && outfile == NULL)
-               printf("warning: no output file specified\n");
+               printf("WARNING no output file specified\n");
 
        if (nl[IA_EXTRALOC].n_type == 0 || nl[I_NEXTRALOC].n_type == 0 ||
            nl[I_UEXTRALOC].n_type == 0 || nl[I_HISTLEN].n_type == 0 ||
@@ -155,6 +153,8 @@
                        process_history(histlen, history);
        }
 
+       printf("%s", adjust((caddr_t)nl[P_VERSION].n_value));
+
        if (config()) {
                if (force == 0 && outfile == NULL) {
                        fprintf(stderr, "not forced\n");
@@ -184,7 +184,9 @@
        struct winsize w;
 #endif
 
-       cd = get_cfdata(0);                     /* get first item */
+       if ((cd = get_cfdata(0)) == NULL)       /* get first item */
+               errx(1, "failed to get first cfdata");
+
        while (cd->cf_attach != 0) {
                maxdev = i;
                totdev = i;

-- 
Best Regards
Edd Barrett