From d82ab819ef751f5c1f0c7e4427cbef466fc4629e Mon Sep 17 00:00:00 2001
From: Andrew Johnson <anj@anl.gov>
Date: Wed, 13 Jul 2022 13:24:54 -0500
Subject: [PATCH] Cap5 support for zero-length long strings

---
 documentation/RELEASE_NOTES.md |  5 +++++
 modules/ca/src/perl/Cap5.xs    | 10 ++++++++--
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/documentation/RELEASE_NOTES.md b/documentation/RELEASE_NOTES.md
index e23488a3d..8ed0628d6 100644
--- a/documentation/RELEASE_NOTES.md
+++ b/documentation/RELEASE_NOTES.md
@@ -16,6 +16,11 @@ should also be read to understand what has changed since earlier releases.
 
 <!-- Insert new items immediately below here ... -->
 
+### Perl CA support for empty long strings
+
+The Perl CA bindings have been fixed to handle zero-length long string data
+properly.
+
 ### `aao` gains `OMSL` and `DOL`
 
 The `aao` record types gains the same `DOL` functionality found
diff --git a/modules/ca/src/perl/Cap5.xs b/modules/ca/src/perl/Cap5.xs
index e17fcbaf0..5da894808 100644
--- a/modules/ca/src/perl/Cap5.xs
+++ b/modules/ca/src/perl/Cap5.xs
@@ -208,6 +208,8 @@ SV * newSVdbr(struct event_handler_args *peha) {
     if (is_primitive) {
         if (value_type == DBR_CHAR) {
             /* Long string => Perl scalar */
+            if (peha->count == 0)
+                return newSVpvn(peha->dbr, 0);
             ((char *)peha->dbr) [peha->count - 1] = 0;
             return newSVpv(peha->dbr, 0);
         }
@@ -278,8 +280,12 @@ SV * newSVdbr(struct event_handler_args *peha) {
         char *str = dbr_value_ptr(peha->dbr, peha->type);
 
         /* Long string => Perl scalar */
-        str[peha->count - 1] = 0;
-        val = newSVpv(str, 0);
+        if (peha->count == 0)
+            val = newSVpvn(str, 0);
+        else {
+            str[peha->count - 1] = 0;
+            val = newSVpv(str, 0);
+        }
     } else if (peha->count == 1) {
         /* Single value => Perl scalar */
         val = newSVdbf(value_type,