kdump: tweaks for the extended errors decoding

Format the message.
Convert category to the source name if known.

Still print the raw value for the category, and the values of the
EXTERROR() optional arguments.

Requested and reviewed by:	mckusick
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D56542

usr.bin/kdump/Makefile

@@ -5,6 +5,7 @@
 PROG=		kdump
 SRCS=		kdump.c subr.c
 CFLAGS+=	-I${SRCTOP}/usr.bin/ktrace
+CFLAGS+=	-I${SRCTOP}/lib/libc/gen
 
 LIBADD=		sysdecode
 .if ${MK_CASPER} != "no"

usr.bin/kdump/kdump.c

@@ -40,6 +40,7 @@
 #include <sys/_bitset.h>
 #include <sys/bitset.h>
 #include <sys/errno.h>
+#include <sys/exterr_cat.h>
 #include <sys/time.h>
 #include <sys/uio.h>
 #include <sys/event.h>
@@ -2442,15 +2443,31 @@ ktrstructarray(struct ktr_struct_array *ksa, size_t buflen)
 	return;
 }
 
+static const char * const cat_to_filenames[] = {
+#include <exterr_cat_filenames.h>
+};
+
+static const char *
+cat_to_filename(int category)
+{
+	if (category < 0 || (unsigned)category >= nitems(cat_to_filenames) ||
+	    cat_to_filenames[category] == NULL)
+		return ("unknown");
+	return (cat_to_filenames[category]);
+}
+
 static void
 ktrexterr(struct ktr_exterr *ke)
 {
+	char *msg;
 	struct uexterror *ue;
 
 	ue = &ke->ue;
-	printf("{ errno %d category %u (src line %u) p1 %#jx p2 %#jx %s }\n",
-	    ue->error, ue->cat, ue->src_line,
-	    (uintmax_t)ue->p1, (uintmax_t)ue->p2, ue->msg);
+	asprintf(&msg, ue->msg, (uintmax_t)ue->p1, (uintmax_t)ue->p2);
+	printf("{ errno %d %s:%u \"%s\" (category %u p1 %#jx p2 %#jx) }\n",
+	    ue->error, cat_to_filename(ue->cat), ue->src_line, msg,
+	    ue->cat, (uintmax_t)ue->p1, (uintmax_t)ue->p2);
+	free(msg);
 }
 
 static void