From c5aa27ee869cc4859e494bde8ddf7da60e177f40 Mon Sep 17 00:00:00 2001
From: Thanos Doukoudakis <thanos.doukoudakis@isode.com>
Date: Wed, 2 Aug 2017 15:30:41 +0100
Subject: Enable log information export to a file
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This patch introduces the “logfile” argument to the client, which can be
used to specify a file path for a log file, where all logging information
will be stored.

Test-Information:

Tested on windows 10 and Ubuntu 17.04

Change-Id: I6a2f14585a72f25e7e78d79cb633e1ddc4d43c3b

diff --git a/Swift/QtUI/QtSwift.cpp b/Swift/QtUI/QtSwift.cpp
index 67fc659..7daa5ce 100644
--- a/Swift/QtUI/QtSwift.cpp
+++ b/Swift/QtUI/QtSwift.cpp
@@ -101,6 +101,7 @@ po::options_description QtSwift::getOptionsDescription() {
 #if QT_VERSION >= 0x040800
         ("language", po::value<std::string>(), "Use a specific language, instead of the system-wide one")
 #endif
+        ("logfile", po::value<std::string>()->implicit_value(""), "Save all logging information to a file")
         ;
     return result;
 }
@@ -189,6 +190,16 @@ QtSwift::QtSwift(const po::variables_map& options) : networkFactories_(&clientMa
         Log::setLogLevel(Swift::Log::debug);
     }
 
+    if (options.count("logfile")) {
+        try {
+            std::string fileName = options["logfile"].as<std::string>();
+            Log::setLogFile(fileName);
+        }
+        catch (...) {
+            SWIFT_LOG(error) << "Error while retrieving the specified log file name from the command line" << std::endl;
+        }
+    }
+
     // Load fonts
     std::vector<std::string> fontNames = {
         "themes/Default/Lato2OFL/Lato-Black.ttf",
diff --git a/Swiften/Base/Log.cpp b/Swiften/Base/Log.cpp
index 0efac7e..9b16531 100644
--- a/Swiften/Base/Log.cpp
+++ b/Swiften/Base/Log.cpp
@@ -16,6 +16,7 @@
 namespace Swift {
 
 static Log::Severity logLevel = Log::warning;
+std::unique_ptr<FILE, Log::LogFileClose> Log::logfile;
 
 Log::Log() {
 }
@@ -25,8 +26,14 @@ Log::~Log() {
     __android_log_print(ANDROID_LOG_VERBOSE, "Swift", stream.str().c_str(), 1);
 #else
     // Using stdio for thread safety (POSIX file i/o calls are guaranteed to be atomic)
-    fprintf(stderr, "%s", stream.str().c_str());
-    fflush(stderr);
+    if (logfile) {
+        fwrite(stream.str().c_str(), sizeof(char), stream.str().size(), logfile.get());
+        fflush(logfile.get());
+    }
+    else {
+        fwrite(stream.str().c_str(), sizeof(char), stream.str().size(), stderr);
+        fflush(stderr);
+    }
 #endif
 }
 
@@ -48,4 +55,10 @@ void Log::setLogLevel(Severity level) {
     logLevel = level;
 }
 
+void Log::setLogFile(const std::string& fileName) {
+    if (!fileName.empty()) {
+        logfile = std::unique_ptr<FILE, Log::LogFileClose>(fopen(fileName.c_str(), "a"));
+    }
+}
+
 }
diff --git a/Swiften/Base/Log.h b/Swiften/Base/Log.h
index 33c969d..e3e04a5 100644
--- a/Swiften/Base/Log.h
+++ b/Swiften/Base/Log.h
@@ -6,6 +6,8 @@
 
 #pragma once
 
+#include <cstdio>
+#include <memory>
 #include <sstream>
 
 #include <Swiften/Base/API.h>
@@ -29,9 +31,18 @@ namespace Swift {
 
             static Severity getLogLevel();
             static void setLogLevel(Severity level);
+            static void setLogFile(const std::string& fileName);
 
         private:
+            struct LogFileClose {
+                void operator()(FILE* p) {
+                    if (p) {
+                        fclose(p);
+                    }
+                }
+            };
             std::ostringstream stream;
+            static std::unique_ptr<FILE, LogFileClose> logfile;
     };
 }
 
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