From 74f3301679fee1d2a1cf67f3da69568a230d75eb Mon Sep 17 00:00:00 2001
From: Mat Sutcliffe <oktal3700@gmail.com>
Date: Fri, 14 Sep 2018 16:53:08 +0100
Subject: [PATCH] Ref T321 Add extended error reporting in
 CAtomicFile::replaceOriginal to try to gather more info on the problem saving
 the data cache session file.

---
 src/blackmisc/atomicfile.cpp | 17 ++++++++++++++++-
 src/blackmisc/stacktrace.cpp | 17 ++++++++++++-----
 src/blackmisc/stacktrace.h   |  7 +++++++
 3 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/src/blackmisc/atomicfile.cpp b/src/blackmisc/atomicfile.cpp
index caf7c3424..cd421c662 100644
--- a/src/blackmisc/atomicfile.cpp
+++ b/src/blackmisc/atomicfile.cpp
@@ -9,6 +9,7 @@
 
 #include "blackmisc/atomicfile.h"
 #include "blackmisc/algorithm.h"
+#include "blackmisc/logmessage.h"
 
 #include <QDir>
 #include <QFileInfo>
@@ -148,8 +149,22 @@ namespace BlackMisc
             m_renameError = true;
             wchar_t *s = nullptr;
             FormatMessage(FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM, nullptr, GetLastError(), 0, reinterpret_cast<LPWSTR>(&s), 0, nullptr);
-            setErrorString((replace ? "ReplaceFile: " : "MoveFileEx: ") + QString::fromWCharArray(s).simplified());
+            // MS 2018-09 Testing T321 ("failed to write session file")
+            //setErrorString((replace ? "ReplaceFile: " : "MoveFileEx: ") + QString::fromWCharArray(s).simplified());
+            CLogMessage(this).error((replace ? "ReplaceFile: " : "MoveFileEx: ") + QString::fromWCharArray(s).simplified() + "\n" + getStackTraceAlways().join("\n"));
             LocalFree(reinterpret_cast<HLOCAL>(s));
+
+            // fall back to non-atomic remove-and-rename
+            if (exists(m_originalFilename))
+            {
+                QFile old(m_originalFilename);
+                if (!old.remove())
+                {
+                    setErrorString(old.errorString());
+                    return;
+                }
+            }
+            rename(m_originalFilename);
         }
     }
 #else
diff --git a/src/blackmisc/stacktrace.cpp b/src/blackmisc/stacktrace.cpp
index 1f6c80f9b..1cb88cddd 100644
--- a/src/blackmisc/stacktrace.cpp
+++ b/src/blackmisc/stacktrace.cpp
@@ -38,13 +38,20 @@
 namespace BlackMisc
 {
 
-#if defined(QT_NO_DEBUG)
+#if defined(QT_DEBUG)
+    QStringList getStackTrace()
+    {
+        return getStackTraceAlways();
+    }
+#else
     QStringList getStackTrace()
     {
         return { "No stack trace with release build" };
     }
-#elif defined(Q_OS_WIN32)
-    QStringList getStackTrace()
+#endif
+
+#if defined(Q_OS_WIN32)
+    QStringList getStackTraceAlways()
     {
         static QMutex mutex;
         QMutexLocker lock(&mutex);
@@ -84,7 +91,7 @@ namespace BlackMisc
         return result;
     }
 #elif defined(Q_CC_GNU)
-    QStringList getStackTrace()
+    QStringList getStackTraceAlways()
     {
         std::array<void*, 100> stack;
         auto frames = backtrace(stack.data(), stack.size());
@@ -128,7 +135,7 @@ namespace BlackMisc
     }
 #else
     // cppcheck-suppress unusedFunction
-    QStringList getStackTrace()
+    QStringList getStackTraceAlways()
     {
         return { "No stack trace on this platform" };
     }
diff --git a/src/blackmisc/stacktrace.h b/src/blackmisc/stacktrace.h
index e2a0bc342..e68820066 100644
--- a/src/blackmisc/stacktrace.h
+++ b/src/blackmisc/stacktrace.h
@@ -19,8 +19,15 @@ namespace BlackMisc
 {
     /*!
      * Returns a stack trace of the current thread of execution as a list of function names.
+     *
+     * Returns a dummy list in release build.
      */
     BLACKMISC_EXPORT QStringList getStackTrace();
+
+    /*!
+     * Returns a stack trace of the current thread of execution as a list of function names.
+     */
+    BLACKMISC_EXPORT QStringList getStackTraceAlways();
 }
 
 #endif