Allow changing the BPTR field

This fixes github issue #97:
Reading into an aai record from a compress or histogram or subArray record
could cause a segfault if the aai record was initialized before the
linked one.

modules/database/src/std/rec/compressRecord.c

@@ -106,7 +106,7 @@ static void monitor(compressRecord *prec)
         db_post_events(prec, &prec->nuse, monitor_mask);
         prec->ouse = prec->nuse;
     }
-    db_post_events(prec, prec->bptr, monitor_mask);
+    db_post_events(prec, (void*)&prec->val, monitor_mask);
 }
 
 static void put_value(compressRecord *prec, double *psource, int n)
@@ -404,7 +404,6 @@ static long cvt_dbaddr(DBADDR *paddr)
 {
     compressRecord *prec = (compressRecord *) paddr->precord;
 
-    paddr->pfield = prec->bptr;
     paddr->no_elements = prec->nsam;
     paddr->field_type = DBF_DOUBLE;
     paddr->field_size = sizeof(double);
@@ -426,6 +425,8 @@ static long get_array_info(DBADDR *paddr, long *no_elements, long *offset)
     epicsUInt32 off = prec->off;
     epicsUInt32 nuse = prec->nuse;
 
+    paddr->pfield = prec->bptr;
+
     if (prec->balg == bufferingALG_FIFO) {
         epicsUInt32 nsam = prec->nsam;
 

modules/database/src/std/rec/histogramRecord.c

@@ -291,7 +291,7 @@ static void monitor(histogramRecord *prec)
     }
     /* send out monitors connected to the value field */
     if (monitor_mask)
-        db_post_events(prec, prec->bptr, monitor_mask);
+        db_post_events(prec, (void*)&prec->val, monitor_mask);
 
     return;
 }
@@ -300,7 +300,6 @@ static long cvt_dbaddr(DBADDR *paddr)
 {
     histogramRecord *prec = (histogramRecord *) paddr->precord;
 
-    paddr->pfield = prec->bptr;
     paddr->no_elements = prec->nelm;
     paddr->field_type = DBF_ULONG;
     paddr->field_size = sizeof(epicsUInt32);
@@ -312,6 +311,7 @@ static long get_array_info(DBADDR *paddr, long *no_elements, long *offset)
 {
     histogramRecord *prec = (histogramRecord *) paddr->precord;
 
+    paddr->pfield = prec->bptr;
     *no_elements =  prec->nelm;
     *offset = 0;
     return 0;

modules/database/src/std/rec/subArrayRecord.c

@@ -161,7 +161,6 @@ static long cvt_dbaddr(DBADDR *paddr)
 {
     subArrayRecord *prec = (subArrayRecord *) paddr->precord;
 
-    paddr->pfield = prec->bptr;
     paddr->no_elements = prec->malm;
     paddr->field_type = prec->ftvl;
     paddr->field_size = dbValueSize(prec->ftvl);
@@ -174,6 +173,7 @@ static long get_array_info(DBADDR *paddr, long *no_elements, long *offset)
 {
     subArrayRecord *prec = (subArrayRecord *) paddr->precord;
 
+    paddr->pfield = prec->bptr;
     if (prec->udf)
        *no_elements = 0;
     else
@@ -293,7 +293,7 @@ static void monitor(subArrayRecord *prec)
     monitor_mask = recGblResetAlarms(prec);
     monitor_mask |= (DBE_LOG|DBE_VALUE);
 
-    db_post_events(prec, prec->bptr, monitor_mask);
+    db_post_events(prec, (void*)&prec->val, monitor_mask);
 
     return;
 }