Don't require a scheme if no partitions are given. Change the code

to handle that case. Note that we still require partitions, so the
change is effectively a no-op.

2 files changed, 13 insertions, 10 deletions

diff --git a/usr.bin/mkimg/mkimg.c b/usr.bin/mkimg/mkimg.c
index 4d55a40..0528352 100644
--- a/usr.bin/mkimg/mkimg.c
+++ b/usr.bin/mkimg/mkimg.c
@@ -541,7 +541,7 @@ main(int argc, char *argv[])
 
 	if (argc > optind)
 		usage("trailing arguments");
-	if (scheme_selected() == NULL)
+	if (scheme_selected() == NULL && nparts > 0)
 		usage("no scheme");
 	if (nparts == 0)
 		usage("no partitions");
@@ -577,8 +577,9 @@ main(int argc, char *argv[])
 		fprintf(stderr, "Sectors per track:   %u\n", nsecs);
 		fprintf(stderr, "Number of heads:     %u\n", nheads);
 		fputc('\n', stderr);
-		fprintf(stderr, "Partitioning scheme: %s\n",
-		    scheme_selected()->name);
+		if (scheme_selected())
+			fprintf(stderr, "Partitioning scheme: %s\n",
+			    scheme_selected()->name);
 		fprintf(stderr, "Output file format:  %s\n",
 		    format_selected()->name);
 		fputc('\n', stderr);
diff --git a/usr.bin/mkimg/scheme.c b/usr.bin/mkimg/scheme.c
index 5c6308f..336f953 100644
--- a/usr.bin/mkimg/scheme.c
+++ b/usr.bin/mkimg/scheme.c
@@ -31,8 +31,10 @@ __FBSDID("$FreeBSD$");
 #include <sys/linker_set.h>
 #include <sys/queue.h>
 #include <sys/stat.h>
+#include <assert.h>
 #include <err.h>
 #include <errno.h>
+#include <limits.h>
 #include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
@@ -104,7 +106,7 @@ scheme_bootcode(int fd)
 {
 	struct stat sb;
 
-	if (scheme->bootcode == 0)
+	if (scheme == NULL || scheme->bootcode == 0)
 		return (ENXIO);
 
 	if (fstat(fd, &sb) == -1)
@@ -130,6 +132,8 @@ scheme_check_part(struct part *p)
 	struct mkimg_alias *iter;
 	enum alias alias;
 
+	assert(scheme != NULL);
+
 	/* Check the partition type alias */
 	alias = scheme_parse_alias(p->alias);
 	if (alias == ALIAS_NONE)
@@ -158,28 +162,26 @@ u_int
 scheme_max_parts(void)
 {
 
-	return (scheme->nparts);
+	return ((scheme == NULL) ? 0 : scheme->nparts);
 }
 
 u_int
 scheme_max_secsz(void)
 {
 
-	return (scheme->maxsecsz);
+	return ((scheme == NULL) ? INT_MAX+1U : scheme->maxsecsz);
 }
 
 lba_t
 scheme_metadata(u_int where, lba_t start)
 {
 
-	return (scheme->metadata(where, start));
+	return ((scheme == NULL) ? start : scheme->metadata(where, start));
 }
 
 int
 scheme_write(lba_t end)
 {
-	int error;
 
-	error = scheme->write(end, bootcode);
-	return (error);
+	return ((scheme == NULL) ? 0 : scheme->write(end, bootcode));
 }