From 39c8d5619a7cba9e95495cc99be9c25ab514f05c Mon Sep 17 00:00:00 2001
From: Dirk Zimoch <dirk.zimoch@psi.ch>
Date: Thu, 13 Feb 2020 22:06:44 +0100
Subject: [PATCH] bugfix: dbGet should not crash because of empty array
 requests

---
 modules/database/src/ioc/db/dbAccess.c |  5 +++++
 modules/database/src/ioc/db/dbDbLink.c | 31 ++++++++++----------------
 2 files changed, 17 insertions(+), 19 deletions(-)

diff --git a/modules/database/src/ioc/db/dbAccess.c b/modules/database/src/ioc/db/dbAccess.c
index da8467a0c..5d63c51d4 100644
--- a/modules/database/src/ioc/db/dbAccess.c
+++ b/modules/database/src/ioc/db/dbAccess.c
@@ -1001,6 +1001,11 @@ long dbGet(DBADDR *paddr, short dbrType,
         } else {
             DBADDR localAddr = *paddr; /* Structure copy */
 
+            if (pfl->no_elements < 1) {
+                status = S_db_badField;
+                goto done;
+            }
+
             localAddr.field_type = pfl->field_type;
             localAddr.field_size = pfl->field_size;
             localAddr.no_elements = pfl->no_elements;
diff --git a/modules/database/src/ioc/db/dbDbLink.c b/modules/database/src/ioc/db/dbDbLink.c
index f3335f4ba..c8452fd86 100644
--- a/modules/database/src/ioc/db/dbDbLink.c
+++ b/modules/database/src/ioc/db/dbDbLink.c
@@ -101,12 +101,6 @@ long dbDbInitLink(struct link *plink, short dbfType)
 
     precord = dbChannelRecord(chan);
 
-    if (dbChannelFinalElements(chan) < 1) {
-        errlogPrintf("Warning: %s.%s=%s has %ld elements. This will not work.\n",
-            plink->precord->name, dbLinkFieldName(plink),
-            dbChannelName(chan), dbChannelFinalElements(chan));
-    }
-
     plink->lset = &dbDb_lset;
     plink->type = DB_LINK;
     plink->value.pv_link.pvt = chan;
@@ -122,12 +116,6 @@ long dbDbInitLink(struct link *plink, short dbfType)
 void dbDbAddLink(struct dbLocker *locker, struct link *plink, short dbfType,
     dbChannel *chan)
 {
-    if (dbChannelFinalElements(chan) < 1) {
-        errlogPrintf("Warning: %s.%s=%s has %ld elements. This will not work.\n",
-            plink->precord->name, dbLinkFieldName(plink),
-            dbChannelName(chan), dbChannelFinalElements(chan));
-    }
-
     plink->lset = &dbDb_lset;
     plink->type = DB_LINK;
     plink->value.pv_link.pvt = chan;
@@ -197,15 +185,20 @@ static long dbDbGetValue(struct link *plink, short dbrType, void *pbuffer,
         fl.ctx = dbfl_context_read;
         fl.type = dbfl_type_rec;
 
-        if (dbChannelFinalElements(chan) < 1)
+        /* For the moment, empty arrays are not supported by EPICS */
+        if (dbChannelFinalElements(chan) > 0)
         {
-            recGblSetSevr(precord, LINK_ALARM, UDF_ALARM);
-            return S_db_badField;
+            dbChannelRunPreChain(chan, &fl);
+            dbChannelRunPostChain(chan, &fl);
+            status = dbChannelGet(chan, dbrType, pbuffer, &options, pnRequest, &fl);
+            if (!status && pnRequest && *pnRequest <= 0)
+                status = S_db_badField;
+        } else {
+            status = S_db_badField;
+        }
+        if (status) {
+            recGblSetSevr(precord, LINK_ALARM, UDF_ALARM);
         }
-        
-        dbChannelRunPreChain(chan, &fl);
-        dbChannelRunPostChain(chan, &fl);
-        status = dbChannelGet(chan, dbrType, pbuffer, &options, pnRequest, &fl);
     } else if (ppv_link->getCvt && ppv_link->lastGetdbrType == dbrType) {
         status = ppv_link->getCvt(dbChannelField(chan), pbuffer, paddr);
     } else {