From 4936502428f0de2d6be43fd65fd0f77a148d73a0 Mon Sep 17 00:00:00 2001
From: Mihai Patrascoiu <mihai.patrascoiu@cern.ch>
Date: Wed, 13 Jun 2018 12:04:27 +0200
Subject: [PATCH] Prevent issue in scenario where stat request returns larger
 size than the actual read request

---
 src/XrdHttp/XrdHttpReq.cc | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/XrdHttp/XrdHttpReq.cc b/src/XrdHttp/XrdHttpReq.cc
index 233a6d4cde7..b8c7d9e4b4e 100644
--- a/src/XrdHttp/XrdHttpReq.cc
+++ b/src/XrdHttp/XrdHttpReq.cc
@@ -1803,6 +1803,15 @@ int XrdHttpReq::PostProcessHTTPReq(bool final_) {
             // Close() if this was the third state of a readv, otherwise read the next chunk
             if ((reqstate == 3) && (ntohs(xrdreq.header.requestid) == kXR_readv)) return 1;
 
+            // Prevent scenario where data is expected but none is actually read
+            // E.g. Accessing files which return the results of a script
+            if ((ntohs(xrdreq.header.requestid) == kXR_read) &&
+                (reqstate > 2) && (iovN == 0)) {
+              TRACEI(REQ, "Stopping request because more data is expected "
+                          "but no data has been read.");
+              return -1;
+            }
+
             // If we are here it's too late to send a proper error message...
             if (xrdresp == kXR_error) return -1;