From 0b070886398cae6735d5b8a28fe3f305c20a54f0 Mon Sep 17 00:00:00 2001
From: Mathew Sutcliffe <oktal3700@gmail.com>
Date: Sat, 22 Oct 2016 23:42:19 +0100
Subject: [PATCH] refs #782 Extended error information when data cache fails to
 write.

---
 src/blackmisc/atomicfile.cpp | 19 +++++++++++++++++--
 src/blackmisc/datacache.cpp  |  6 +++---
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/src/blackmisc/atomicfile.cpp b/src/blackmisc/atomicfile.cpp
index 33b984353..9cc337fab 100644
--- a/src/blackmisc/atomicfile.cpp
+++ b/src/blackmisc/atomicfile.cpp
@@ -18,6 +18,7 @@
 
 #if defined(Q_OS_POSIX)
 #include <stdio.h>
+#include <errno.h>
 #elif defined(Q_OS_WIN32)
 #include <windows.h>
 #endif
@@ -90,13 +91,27 @@ namespace BlackMisc
     void CAtomicFile::replaceOriginal()
     {
         auto result = ::rename(qPrintable(fileName()), qPrintable(m_originalFilename));
-        if (result < 0) { m_renameError = true; }
+        if (result < 0)
+        {
+            m_renameError = true;
+            char s[1024] {};
+            auto x = strerror_r(errno, s, sizeof(s));
+            setErrorString(QString::fromLocal8Bit(s));
+            static_assert(std::is_same<decltype(x), int>::value, "Non-standard signature of POSIX function strerror_r, check documentation.");
+        }
     }
 #elif defined(Q_OS_WIN32)
     void CAtomicFile::replaceOriginal()
     {
         auto result = MoveFileExA(qPrintable(fileName()), qPrintable(m_originalFilename), MOVEFILE_REPLACE_EXISTING);
-        if (! result) { m_renameError = true; }
+        if (! result)
+        {
+            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(QString::fromWCharArray(s));
+            LocalFree(reinterpret_cast<HLOCAL>(s));
+        }
     }
 #else
     void CAtomicFile::replaceOriginal()
diff --git a/src/blackmisc/datacache.cpp b/src/blackmisc/datacache.cpp
index ab7b02331..9fc166624 100644
--- a/src/blackmisc/datacache.cpp
+++ b/src/blackmisc/datacache.cpp
@@ -479,7 +479,7 @@ namespace BlackMisc
 
         if (! revisionFile.checkedClose())
         {
-            CLogMessage(this).error("Failed to write to %1: %2") << revisionFile.fileName() << revisionFile.errorString();
+            CLogMessage(this).error("Failed to write to %1: %2 (%3 %4)") << revisionFile.fileName() << revisionFile.errorString() << QThread::currentThread()->objectName() << Q_FUNC_INFO;
         }
     }
 
@@ -623,7 +623,7 @@ namespace BlackMisc
 
             if (!(revisionFile.seek(0) && revisionFile.resize(0) && revisionFile.write(QJsonDocument(json).toJson()) && revisionFile.checkedClose()))
             {
-                CLogMessage(this).error("Failed to write to %1: %2") << revisionFile.fileName() << revisionFile.errorString();
+                CLogMessage(this).error("Failed to write to %1: %2 (%3 %4)") << revisionFile.fileName() << revisionFile.errorString() << QThread::currentThread()->objectName() << Q_FUNC_INFO;
             }
         }
         m_lockFile.unlock();
@@ -776,7 +776,7 @@ namespace BlackMisc
         json.insert("uuid", uuid.toString());
         if (!(file.seek(0) && file.resize(0) && file.write(QJsonDocument(json).toJson()) && file.checkedClose()))
         {
-            CLogMessage(this).error("Failed to write to session file %1: %2") << m_filename << file.errorString();
+            CLogMessage(this).error("Failed to write to session file %1: %2 (%3 %4)") << m_filename << file.errorString() << QThread::currentThread()->objectName() << Q_FUNC_INFO;
         }
     }