From 9af080c351c40a4f56d37174253d33a9f4ffdb69 Mon Sep 17 00:00:00 2001
From: Michael Hendricks <michael@ndrix.org>
Date: Fri, 2 Mar 2012 12:31:16 -0700
Subject: [PATCH] Reopen debug.log on SIGHUP

The best log rotation method formerly available was to configure
logrotate with the copytruncate option.  As described in the logrotate
documentation, "there is a very small time slice between copying the
file and truncating it, so some logging data might be lost".

By sending SIGHUP to the server process, one can now reopen the debug
log file without losing any data.
---
 src/init.cpp | 12 +++++++++++-
 src/util.cpp |  9 +++++++++
 src/util.h   |  1 +
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/src/init.cpp b/src/init.cpp
index b027a53d8..726950bdb 100644
--- a/src/init.cpp
+++ b/src/init.cpp
@@ -80,6 +80,10 @@ void HandleSIGTERM(int)
     fRequestShutdown = true;
 }
 
+void HandleSIGHUP(int)
+{
+    fReopenDebugLog = true;
+}
 
 
 
@@ -285,7 +289,13 @@ bool AppInit2()
     sa.sa_flags = 0;
     sigaction(SIGTERM, &sa, NULL);
     sigaction(SIGINT, &sa, NULL);
-    sigaction(SIGHUP, &sa, NULL);
+
+    // Reopen debug.log on SIGHUP
+    struct sigaction sa_hup;
+    sa_hup.sa_handler = HandleSIGHUP;
+    sigemptyset(&sa_hup.sa_mask);
+    sa_hup.sa_flags = 0;
+    sigaction(SIGHUP, &sa_hup, NULL);
 #endif
 
     fTestNet = GetBoolArg("-testnet");
diff --git a/src/util.cpp b/src/util.cpp
index d143306ae..e3a49dcbc 100644
--- a/src/util.cpp
+++ b/src/util.cpp
@@ -70,6 +70,7 @@ bool fTestNet = false;
 bool fNoListen = false;
 bool fLogTimestamps = false;
 CMedianFilter<int64> vTimeOffsets(200,0);
+bool fReopenDebugLog = false;
 
 // Init openssl library multithreading support
 static CCriticalSection** ppmutexOpenSSL;
@@ -213,6 +214,14 @@ inline int OutputDebugStringF(const char* pszFormat, ...)
             static boost::mutex mutexDebugLog;
             boost::mutex::scoped_lock scoped_lock(mutexDebugLog);
 
+            // reopen the log file, if requested
+            if (fReopenDebugLog) {
+                fReopenDebugLog = false;
+                boost::filesystem::path pathDebug = GetDataDir() / "debug.log";
+                if (freopen(pathDebug.string().c_str(),"a",fileout) != NULL)
+                    setbuf(fileout, NULL); // unbuffered
+            }
+
             // Debug print useful for profiling
             if (fLogTimestamps && fStartedNewLine)
                 fprintf(fileout, "%s ", DateTimeStrFormat("%x %H:%M:%S", GetTime()).c_str());
diff --git a/src/util.h b/src/util.h
index f7bdaf533..edef35444 100644
--- a/src/util.h
+++ b/src/util.h
@@ -121,6 +121,7 @@ extern std::string strMiscWarning;
 extern bool fTestNet;
 extern bool fNoListen;
 extern bool fLogTimestamps;
+extern bool fReopenDebugLog;
 
 void RandAddSeed();
 void RandAddSeedPerfmon();