4061e76e6ead3d4a59704aab422abef16e3cfd2e
hiram
  Tue Feb 19 11:41:29 2019 -0800
beginning to return data from track hub bigBed files refs #18869

diff --git src/hg/hubApi/apiUtils.c src/hg/hubApi/apiUtils.c
index 8c2f3d0..2c901fe 100644
--- src/hg/hubApi/apiUtils.c
+++ src/hg/hubApi/apiUtils.c
@@ -1,50 +1,68 @@
 /* utility functions for data API business */
 
 #include "dataApi.h"
 
 void apiErrAbort(char *format, ...)
 /* Issue an error message in json format, and exit(0) */
 {
 char errMsg[2048];
 va_list args;
 va_start(args, format);
 vsnprintf(errMsg, sizeof(errMsg), format, args);
 struct jsonWrite *jw = apiStartOutput();
 jsonWriteString(jw, "error", errMsg);
 jsonWriteObjectEnd(jw);
 fputs(jw->dy->string,stdout);
 exit(0);
 }
 
 struct jsonWrite *apiStartOutput()
 /* begin json output with standard header information for all requests */
 {
 time_t timeNow = time(NULL);
 // struct tm tm;
 // gmtime_r(&timeNow, &tm);
 struct jsonWrite *jw = jsonWriteNew();
 jsonWriteObjectStart(jw, NULL);
 jsonWriteString(jw, "apiVersion", "0.1");
 jsonWriteString(jw, "source", "UCSantaCruz");
 jsonWriteDateFromUnix(jw, "downloadTime", (long long) timeNow);
 jsonWriteNumber(jw, "downloadTimeStamp", (long long) timeNow);
 return jw;
 }
 
 int tableColumns(struct sqlConnection *conn, struct jsonWrite *jw, char *table)
 /* output the column names, and their MySQL data type, for the given table
  *  return number of columns (aka 'fields')
  */
 {
 jsonWriteListStart(jw, "columnNames");
 struct sqlFieldInfo *fi, *fiList = sqlFieldInfoGet(conn, table);
 int columnCount = slCount(fiList);
 for (fi = fiList; fi; fi = fi->next)
     {
     jsonWriteObjectStart(jw, NULL);
     jsonWriteString(jw, fi->field, fi->type);
     jsonWriteObjectEnd(jw);
     }
 jsonWriteListEnd(jw);
 return columnCount;
 }
+
+struct trackHub *errCatchTrackHubOpen(char *hubUrl)
+/* use errCatch around a trackHub open in case it fails */
+{
+struct trackHub *hub = NULL;
+struct errCatch *errCatch = errCatchNew();
+if (errCatchStart(errCatch))
+    {
+    hub = trackHubOpen(hubUrl, "");
+    }
+errCatchEnd(errCatch);
+if (errCatch->gotError)
+    {
+    apiErrAbort("error opening hubUrl: '%s', '%s'", hubUrl,  errCatch->message->string);
+    }
+errCatchFree(&errCatch);
+return hub;
+}