From 097b93aa8b3a1f9cbdcaa5dc5eab71f89b8881af Mon Sep 17 00:00:00 2001
From: Koennecke Mark <mark.koennecke@psi.ch>
Date: Tue, 17 May 2016 11:30:38 +0200
Subject: [PATCH] Added a loglsisten command for listening into the log

---
 loglisten.c | 95 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 logv2.c     |  2 +-
 make_gen    |  2 +-
 ofac.c      |  1 +
 4 files changed, 98 insertions(+), 2 deletions(-)
 create mode 100644 loglisten.c

diff --git a/loglisten.c b/loglisten.c
new file mode 100644
index 00000000..111b251a
--- /dev/null
+++ b/loglisten.c
@@ -0,0 +1,95 @@
+/**
+ * This is a means to listen into the stream of log messages from the logv2 
+ * logging system.
+ *
+ * Mark Koennecke, May 2016
+ */
+#include <sics.h>
+#include <logv2.h>
+#include <lld.h>
+
+/*
+  From logv2.c
+*/
+extern int subsystemFromText(const char *text);
+/*=============================================================================*/
+static int listenerList;
+static int callbackRegistered = 0;
+
+typedef struct {
+  SConnection *pCon;
+  char subsystem[64];
+} ListenEntry;
+/*-----------------------------------------------------------------------------*/
+static void LogListenCallback(unsigned int severity, const char *timeStamp, 
+			    const char *subsystem, 
+			    const char *message, void *userData)
+{
+  ListenEntry current;
+  int status, cleanupNeeded = 0;
+
+  status = LLDnodePtr2First(listenerList);
+  while(status != 0){
+    LLDnodeDataTo(listenerList,&current);
+    if(strcmp(current.subsystem,subsystem) == 0) {
+      if(SCisConnected(current.pCon)){
+	SCPureSockWrite(current.pCon,(char *)message,eValue);
+      } else {
+	cleanupNeeded = 1;
+      }
+    }
+    status = LLDnodePtr2Next(listenerList);
+  }
+
+  /*
+    lld lists sometimes get confused when deleting nodes on the fly.
+    This is why this has been put into a separate loop
+  */
+  if(cleanupNeeded){
+    status = LLDnodePtr2First(listenerList);
+    while(status != 0){
+      LLDnodeDataTo(listenerList,&current);
+      if(!SCisConnected(current.pCon)){
+	SCDeleteConnection(current.pCon);
+	LLDnodeDelete(listenerList);
+      }
+      status = LLDnodePtr2Next(listenerList);
+    }
+  }
+
+}
+/*-----------------------------------------------------------------------------*/
+static int LogListenAction(SConnection * pCon, SicsInterp * pSics,
+                            void *pData, int argc, char *argv[])
+{
+  ListenEntry listLog;
+
+  if(argc < 2){ 
+    SCWrite(pCon,"ERROR: need subsystem argument for loglisten", eError);
+    return 0;
+  }
+  
+  if(subsystemFromText(argv[1]) < 0){
+    SCPrintf(pCon,eError, "ERROR: invalid subsystem %s specified", argv[1]);
+    return 0;
+  }
+
+
+  listLog.pCon = SCCopyConnection(pCon);
+  strncpy(listLog.subsystem,argv[1],sizeof(listLog.subsystem));
+  LLDnodeAppendFrom(listenerList,&listLog);
+
+  if(!callbackRegistered){
+    RegisterLogCallback(LogListenCallback,NULL);
+    callbackRegistered = 1;
+  }
+
+  SCSendOK(pCon);
+  return 1;
+}
+/*-----------------------------------------------------------------------------*/
+void LogListenInit(void)
+{
+  listenerList = LLDcreate(sizeof(ListenEntry));
+  AddCmd("loglisten", LogListenAction);
+}
diff --git a/logv2.c b/logv2.c
index 8ac06b87..4cbdf83f 100644
--- a/logv2.c
+++ b/logv2.c
@@ -202,7 +202,7 @@ static unsigned int sevFromText(const char *txt)
   return sev;
 }
 /*=============================================================================*/
-static unsigned int subsystemFromText(const char *text)
+int subsystemFromText(const char *text)
 {
   int i;
   static const char *subText[] = {"sys",
diff --git a/make_gen b/make_gen
index f4f8cad0..07887aa0 100644
--- a/make_gen
+++ b/make_gen
@@ -14,7 +14,7 @@ SOBJ =  network.o ifile.o conman.o SCinter.o splitter.o passwd.o \
        sicsexit.o  costa.o task.o $(FORTIFYOBJ) testprot.o\
        macro.o ofac.o obpar.o obdes.o drive.o status.o intserv.o  \
        devexec.o mumo.o mumoconf.o selector.o selvar.o fupa.o lld.o \
-       lld_blob.o  strrepl.o lin2ang.o fomerge.o  \
+       lld_blob.o  strrepl.o lin2ang.o fomerge.o  loglisten.o \
        script.o o2t.o  alias.o  stringdict.o sdynar.o \
        histmem.o histdriv.o histsim.o  interface.o callback.o  \
         event.o emon.o evcontroller.o evdriver.o simev.o perfmon.o \
diff --git a/ofac.c b/ofac.c
index df88921e..9220920e 100644
--- a/ofac.c
+++ b/ofac.c
@@ -55,6 +55,7 @@ static void InitGeneral(void)
   INIT(InitTaskOBJ);
   INIT(RemoteObjectInit);
   INIT(Logv2Init);
+  INIT(LogListenInit);
   INIT(SiteInit);               /* site specific initializations */
 }