Added -i (ignore v1 features) support to imagedump. Prevents it

from looking at the embedded (and deprecated) blockindex field in
the headers.  Now imagedump won't complain if you run it on a
piece of a split image.

os/imagezip/imagedump.8

@@ -11,7 +11,7 @@
 .Nd dump information about an imagezip compressed image file
 .Sh SYNOPSIS
 .Nm
-.Op Fl dv
+.Op Fl div
 .Ar imagefile ...
 .Sh DESCRIPTION
 The
@@ -38,6 +38,15 @@ options can be specified to dump various levels of structure within the
 image file.
 .Pp
 The
+.Fl i
+option tells
+.Nm
+to ignore the deprecated blockindex field in chunk headers.
+You need this option when running
+.Nm
+on pieces of a split image.
+.Pp
+The
 .Fl v
 option prints version information about
 .Nm

os/imagezip/imagedump.c

@@ -22,6 +22,7 @@
 
 static int detail = 0;
 static int dumpmap = 0;
+static int ignorev1 = 0;
 static int infd = -1;
 
 static unsigned long long wasted;
@@ -40,11 +41,14 @@ main(int argc, char **argv)
 	int ch, version = 0;
 	extern char build_info[];
 
-	while ((ch = getopt(argc, argv, "dmv")) != -1)
+	while ((ch = getopt(argc, argv, "dimv")) != -1)
 		switch(ch) {
 		case 'd':
 			detail++;
 			break;
+		case 'i':
+			ignorev1++;
+			break;
 		case 'm':
 			dumpmap++;
 			detail = 0;
@@ -181,7 +185,11 @@ dumpfile(char *name, int fd)
 				return;
 			}
 
-			chunkcount = hdr->blocktotal;
+			if (ignorev1) {
+				chunkcount = 0;
+				checkindex = 0;
+			} else
+				chunkcount = hdr->blocktotal;
 			if ((filesize / SUBBLOCKSIZE) != chunkcount) {
 				if (chunkcount != 0) {
 					if (isstdin)
@@ -197,9 +205,11 @@ dumpfile(char *name, int fd)
 						       (filesize/SUBBLOCKSIZE),
 						       chunkcount);
 				} else if (magic == COMPRESSED_V1) {
-					printf("%s: WARNING: zero chunk count, "
-					       "ignoring block fields\n",
-					       name);
+					if (!ignorev1)
+						printf("%s: WARNING: "
+						       "zero chunk count, "
+						       "ignoring block fields\n",
+						       name);
 					checkindex = 0;
 				}
 			}
@@ -208,7 +218,7 @@ dumpfile(char *name, int fd)
 			       name, filesize,
 			       (unsigned long)(filesize / SUBBLOCKSIZE),
 			       hdr->magic - COMPRESSED_MAGIC_BASE + 1);
-		} else if (chunkno == 1) {
+		} else if (chunkno == 1 && !ignorev1) {
 			blockhdr_t *hdr = (blockhdr_t *)chunkbuf;
 
 			/*