fix crash [#27158] Appending crash with preview.

source/blender/blenloader/BLO_readfile.h

@@ -148,7 +148,7 @@ BLO_blendhandle_from_memory(
  * 
  * @param bh The blendhandle to access.
  * @param ofblocktype The type of names to get.
- * @param totnames The length of the returned list.
+ * @param tot_names The length of the returned list.
  * @return A BLI_linklist of strings. The string links
  * should be freed with malloc.
  */
@@ -156,7 +156,7 @@ BLO_blendhandle_from_memory(
 BLO_blendhandle_get_datablock_names(
 	BlendHandle *bh, 
 	int ofblocktype,
-	int *totnames);
+	int *tot_names);
 
 /**
  * Gets the previews of all the datablocks in a file
@@ -165,13 +165,15 @@ BLO_blendhandle_get_datablock_names(
  * 
  * @param bh The blendhandle to access.
  * @param ofblocktype The type of names to get.
+ * @param tot_prev The length of the returned list.
  * @return A BLI_linklist of PreviewImage. The PreviewImage links
  * should be freed with malloc.
  */
 	struct LinkNode*
 BLO_blendhandle_get_previews(
 	BlendHandle *bh, 
-	int ofblocktype);
+	int ofblocktype,
+	int *tot_prev);
 
 /**
  * Gets the names of all the datablock groups in a

source/blender/blenloader/intern/readblenentry.c

@@ -144,7 +144,7 @@ LinkNode *BLO_blendhandle_get_datablock_names(BlendHandle *bh, int ofblocktype,
 	return names;
 }
 
-LinkNode *BLO_blendhandle_get_previews(BlendHandle *bh, int ofblocktype) 
+LinkNode *BLO_blendhandle_get_previews(BlendHandle *bh, int ofblocktype, int *tot_prev)
 {
 	FileData *fd= (FileData*) bh;
 	LinkNode *previews= NULL;
@@ -153,6 +153,7 @@ LinkNode *BLO_blendhandle_get_previews(BlendHandle *bh, int ofblocktype)
 	int npreviews = 0;
 	PreviewImage* prv = NULL;
 	PreviewImage* new_prv = NULL;
+	int tot= 0;
 	
 	for (bhead= blo_firstbhead(fd); bhead; bhead= blo_nextbhead(fd, bhead)) {
 		if (bhead->code==ofblocktype) {
@@ -166,6 +167,7 @@ LinkNode *BLO_blendhandle_get_previews(BlendHandle *bh, int ofblocktype)
 				case ID_LA: /* fall through */
 					new_prv = MEM_callocN(sizeof(PreviewImage), "newpreview");
 					BLI_linklist_prepend(&previews, new_prv);
+					tot++;
 					looking = 1;
 					break;
 				default:
@@ -213,7 +215,8 @@ LinkNode *BLO_blendhandle_get_previews(BlendHandle *bh, int ofblocktype)
 		}
 		
 	}
-	
+
+	*tot_prev= tot;
 	return previews;
 }
 

source/blender/editors/space_file/filelist.c

@@ -1007,7 +1007,7 @@ void filelist_from_library(struct FileList* filelist)
 {
 	LinkNode *l, *names, *previews;
 	struct ImBuf* ima;
-	int ok, i, nnames, idcode;
+	int ok, i, nprevs, nnames, idcode;
 	char filename[FILE_MAXDIR+FILE_MAXFILE];
 	char dir[FILE_MAX], group[GROUP_MAX];	
 	
@@ -1031,17 +1031,18 @@ void filelist_from_library(struct FileList* filelist)
 	
 	idcode= groupname_to_code(group);
 
-		// memory for strings is passed into filelist[i].relname
-		// and free'd in freefilelist
-	previews = NULL;
+	/* memory for strings is passed into filelist[i].relname
+	 * and free'd in freefilelist */
 	if (idcode) {
-		previews= BLO_blendhandle_get_previews(filelist->libfiledata, idcode);
+		previews= BLO_blendhandle_get_previews(filelist->libfiledata, idcode, &nprevs);
 		names= BLO_blendhandle_get_datablock_names(filelist->libfiledata, idcode, &nnames);
 		/* ugh, no rewind, need to reopen */
 		BLO_blendhandle_close(filelist->libfiledata);
 		filelist->libfiledata= BLO_blendhandle_from_file(dir, NULL);
 		
 	} else {
+		previews= NULL;
+		nprevs= 0;
 		names= BLO_blendhandle_get_linkable_groups(filelist->libfiledata);
 		nnames= BLI_linklist_length(names);
 	}
@@ -1064,7 +1065,10 @@ void filelist_from_library(struct FileList* filelist)
 		}
 	}
 	
-	if(previews) {
+	if(previews && (nnames != nprevs)) {
+		printf("filelist_from_library: error, found %d items, %d previews\n", nnames, nprevs);
+	}
+	else if(previews) {
 		for (i=0, l= previews; i<nnames; i++, l= l->next) {
 			PreviewImage *img= l->link;