From f09b475c4b88df879a77b4fc933a2dd9af32098d Mon Sep 17 00:00:00 2001
From: Jakub Jelen <jjelen@redhat.com>
Date: Fri, 24 Mar 2023 20:28:09 +0100
Subject: [PATCH] sftpserver: Properly handle empty files and EOF while reading

Signed-off-by: Jakub Jelen <jjelen@redhat.com>
Reviewed-by: Andreas Schneider <asn@cryptomilk.org>
Reviewed-by: Anderson Toshiyuki Sasaki <ansasaki@redhat.com>
---
 src/sftpserver.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/sftpserver.c b/src/sftpserver.c
index 7fc170ef..d51dcf03 100644
--- a/src/sftpserver.c
+++ b/src/sftpserver.c
@@ -965,11 +965,18 @@ process_read(sftp_client_message client_msg)
             SSH_LOG(SSH_LOG_PROTOCOL, "read file error!");
             free(buffer);
             return SSH_ERROR;
+        } else if (readn == 0) {
+            /* no more data to read, EOF ? */
+            break;
         }
         allreadn += readn;
     } while (allreadn < (ssize_t)client_msg->len);
 
-    sftp_reply_data(client_msg, buffer, allreadn);
+    if (allreadn > 0) {
+        sftp_reply_data(client_msg, buffer, allreadn);
+    } else {
+        sftp_reply_status(client_msg, SSH_FX_EOF, NULL);
+    }
 
     free(buffer);
     return SSH_OK;