From afd375a7f86730dd865aebac257f40c58fc690df Mon Sep 17 00:00:00 2001
From: Robin Mueller <robin.mueller.m@gmail.com>
Date: Sun, 22 Aug 2021 20:24:50 +0200
Subject: [PATCH] minor fix for canonical read handling

---
 hal/src/fsfw_hal/linux/uart/UartComIF.cpp | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/hal/src/fsfw_hal/linux/uart/UartComIF.cpp b/hal/src/fsfw_hal/linux/uart/UartComIF.cpp
index 29a79205..99f5f8df 100644
--- a/hal/src/fsfw_hal/linux/uart/UartComIF.cpp
+++ b/hal/src/fsfw_hal/linux/uart/UartComIF.cpp
@@ -1,6 +1,7 @@
-#include "fsfw_hal/linux/uart/UartComIF.h"
+#include "UartComIF.h"
 #include "OBSWConfig.h"
 
+#include "fsfw_hal/linux/utility.h"
 #include "fsfw/serviceinterface/ServiceInterface.h"
 
 #include <cstring>
@@ -353,12 +354,13 @@ ReturnValue_t UartComIF::handleCanonicalRead(UartCookie& uartCookie, UartDeviceM
     size_t maxReplySize = uartCookie.getMaxReplyLen();
     int fd = iter->second.fileDescriptor;
     auto bufferPtr = iter->second.replyBuffer.data();
+    iter->second.replyLen = 0;
     do {
         size_t allowedReadSize = 0;
         if(currentBytesRead >= maxReplySize) {
             // Overflow risk. Emit warning, trigger event and break. If this happens,
             // the reception buffer is not large enough or data is not polled often enough.
-#if OBSW_VERBOSE_LEVEL >= 1
+#if FSFW_VERBOSE_LEVEL >= 1
 #if FSFW_CPP_OSTREAM_ENABLED == 1
             sif::warning << "UartComIF::requestReceiveMessage: Next read would cause overflow!"
                     << std::endl;
@@ -376,7 +378,20 @@ ReturnValue_t UartComIF::handleCanonicalRead(UartCookie& uartCookie, UartDeviceM
 
         bytesRead = read(fd, bufferPtr, allowedReadSize);
         if (bytesRead < 0) {
-            return RETURN_FAILED;
+            // EAGAIN: No data available in non-blocking mode
+            if(errno != EAGAIN) {
+#if FSFW_VERBOSE_LEVEL >= 1
+#if FSFW_CPP_OSTREAM_ENABLED == 1
+                sif::warning << "UartComIF::handleCanonicalRead: read failed with code" <<
+                        errno << ": " << strerror(errno) << std::endl;
+#else
+                sif::printWarning("UartComIF::handleCanonicalRead: read failed with code %d: %s\n",
+                        errno, strerror(errno));
+#endif
+#endif
+                return RETURN_FAILED;
+            }
+
         }
         else if(bytesRead > 0) {
             iter->second.replyLen += bytesRead;