Currently trying to turn an oversized directory into a VVFAT image will

result in a cryptic error (and an abort):
  qemu: block-vvfat.c:97: array_get: Assertion `index < array->next' failed.
  Aborted

Turn this into an actually useful error message:
  Directory does not fit in FAT16 (capacity 504MB)
  qemu: could not open disk image fat:$DIR/


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5665 c046a42c-6fe2-441c-8c8c-71466251a162

block-vvfat.c

@@ -890,7 +890,6 @@ static int init_directories(BDRVVVFATState* s,
     s->path = mapping->path;
 
     for (i = 0, cluster = 0; i < s->mapping.next; i++) {
-	int j;
 	/* MS-DOS expects the FAT to be 0 for the root directory
 	 * (except for the media byte). */
 	/* LATER TODO: still true for FAT32? */
@@ -923,20 +922,25 @@ static int init_directories(BDRVVVFATState* s,
 
 	assert(mapping->begin < mapping->end);
 
+	/* next free cluster */
+	cluster = mapping->end;
+
+	if(cluster > s->cluster_count) {
+	    fprintf(stderr,"Directory does not fit in FAT%d (capacity %s)\n",
+		    s->fat_type,
+		    s->fat_type == 12 ? s->sector_count == 2880 ? "1.44 MB"
+								: "2.88 MB"
+				      : "504MB");
+	    return -EINVAL;
+	}
+
 	/* fix fat for entry */
 	if (fix_fat) {
+	    int j;
 	    for(j = mapping->begin; j < mapping->end - 1; j++)
 		fat_set(s, j, j+1);
 	    fat_set(s, mapping->end - 1, s->max_fat_value);
 	}
-
-	/* next free cluster */
-	cluster = mapping->end;
-
-	if(cluster > s->cluster_count) {
-	    fprintf(stderr,"Directory does not fit in FAT%d\n",s->fat_type);
-	    return -1;
-	}
     }
 
     mapping = array_get(&(s->mapping), 0);