098b0567c51ecc6e2098f17d8fbcf9dcf4f830ca
angie
  Tue Nov 13 12:25:19 2012 -0800
Problem: when we have a BAM or VCF track with per-chromosome files,and then view a chromosome for which there is no file (e.g. a random
or hap), hgTracks was hitting an early errAbort that is more appropriate
for a single-big-file track that is missing its filename. Fix: allow
bbiNameFromTableChrom to return NULL if there is a seqName column and
there simply isn't a file for that seqName.

diff --git src/hg/inc/hdb.h src/hg/inc/hdb.h
index ebd840f..5703195 100644
--- src/hg/inc/hdb.h
+++ src/hg/inc/hdb.h
@@ -879,18 +879,19 @@
  * custom track by name, otherwise pass NULL
  */
 
 boolean hIsBigBed(char *database, char *table, struct trackDb *parent, struct customTrack *(*ctLookupName)(char *table));
 /* Return TRUE if table corresponds to a bigBed file.
  * if table has no parent trackDb pass NULL for parent
  * If this is a custom track, pass in function ctLookupName(table) which looks up a
  * custom track by name, otherwise pass NULL
  */
 
 char *bbiNameFromSettingOrTable(struct trackDb *tdb, struct sqlConnection *conn, char *table);
 /* Return file name from bigDataUrl or little table. */
 
 char *bbiNameFromSettingOrTableChrom(struct trackDb *tdb, struct sqlConnection *conn, char *table,
 				     char *seqName);
-/* Return file name from bigDataUrl or little table (which might have a seqName column). */
+/* Return file name from bigDataUrl or little table that might have a seqName column.
+ * If table does have a seqName column, return NULL if there is no file for seqName. */
 
 #endif /* HDB_H */