From 628d791b26062945fad4afa5985f6b84f46f16d4 Mon Sep 17 00:00:00 2001
From: Jiri Vymazal <jvymazal@redhat.com>
Date: Tue, 23 Jul 2019 11:28:31 +0200
Subject: [PATCH] Add "fsync" option for imjournal

The new option makes possible to force physical write of stateFile
to persistent storage, ensuring we do not lose/duplicate messages
in case of hard crash or power loss.
---
 plugins/imjournal/imjournal.c | 41 +++++++++++++++----
 1 file changed, 32 insertions(+), 9 deletitions(-)

diff --git a/plugins/imjournal/imjournal.c b/plugins/imjournal/imjournal.c
index 5739bf408c..6c8829243a 100644
--- a/plugins/imjournal/imjournal.c
+++ b/plugins/imjournal/imjournal.c
@@ -24,6 +24,7 @@
 #include "config.h"
 #include "rsyslog.h"
 #include <stdio.h>
+#include <dirent.h>
 #include <assert.h>
 #include <string.h>
 #include <stdarg.h>
@@ -81,6 +82,7 @@ static struct configSettings_s {
 	int bUseJnlPID;
 	char *dfltTag;
 	int bWorkAroundJournalBug;
+	int bFsync;
 } cs;
 
 static rsRetVal facilityHdlr(uchar **pp, void *pVal);
@@ -99,7 +99,8 @@ static struct cnfparamdescr modpdescr[] = {
 	{ "defaultfacility", eCmdHdlrString, 0 },
 	{ "usepidfromsystem", eCmdHdlrBinary, 0 },
 	{ "defaulttag", eCmdHdlrGetWord, 0 },
-	{ "workaroundjournalbug", eCmdHdlrBinary, 0 }
+	{ "workaroundjournalbug", eCmdHdlrBinary, 0 },
+	{ "fsync", eCmdHdlrBinary, 0 }
 };
 static struct cnfparamblk modpblk =
 	{ CNFPARAMBLK_VERSION,
@@ -437,7 +437,7 @@ persistJournalState(int trySave)
 persistJournalState(int trySave)
 {
 	DEFiRet;
-	FILE *sf; /* state file */
+	FILE *sf = NULL; /* state file */
 	char tmp_sf[MAXFNAME];
 	int ret = 0;
 
@@ -468,13 +468,6 @@ persistJournalState(int trySave)
 	ret = fputs(last_cursor, sf);
 	if (ret < 0) {
 		errmsg.LogError(errno, RS_RET_IO_ERROR, "imjournal: failed to save cursor to: '%s'", tmp_sf);
-		ret = fclose(sf);
-		ABORT_FINALIZE(RS_RET_IO_ERROR);
-	}
-
-	ret = fclose(sf);
-	if (ret < 0) {
-		errmsg.LogError(errno, RS_RET_IO_ERROR, "imjournal: fclose() failed for path: '%s'", tmp_sf);
 		ABORT_FINALIZE(RS_RET_IO_ERROR);
 	}
 
@@ -484,7 +477,30 @@ persistJournalState(int trySave)
 		ABORT_FINALIZE(RS_RET_IO_ERROR);
 	}
 
+	if (cs.bFsync) {
+		if (fsync(fileno(sf)) != 0) {
+			LogError(errno, RS_RET_IO_ERROR, "imjournal: fsync on '%s' failed", cs.stateFile);
+			ABORT_FINALIZE(RS_RET_IO_ERROR);
+		}
+		/* In order to guarantee physical write we need to force parent sync as well */
+		DIR *wd;
+		if (!(wd = opendir((char *)glbl.GetWorkDir()))) {
+			LogError(errno, RS_RET_IO_ERROR, "imjournal: failed to open '%s' directory", glbl.GetWorkDir());
+			ABORT_FINALIZE(RS_RET_IO_ERROR);
+		}
+		if (fsync(dirfd(wd)) != 0) {
+			LogError(errno, RS_RET_IO_ERROR, "imjournal: fsync on '%s' failed", glbl.GetWorkDir());
+			ABORT_FINALIZE(RS_RET_IO_ERROR);
+		}
+	}
+
 finalize_it:
+	if (sf != NULL) {
+		if (fclose(sf) == EOF) {
+			LogError(errno, RS_RET_IO_ERROR, "imjournal: fclose() failed for path: '%s'", tmp_sf);
+			iRet = RS_RET_IO_ERROR;
+		}
+	}
 	RETiRet;
 }
 
@@ -746,6 +747,8 @@ CODESTARTbeginCnfLoad
 	cs.iDfltFacility = DFLT_FACILITY;
 	cs.dfltTag = NULL;
 	cs.bUseJnlPID = 0;
+	cs.bWorkAroundJournalBug = 0;
+	cs.bFsync = 0;
 ENDbeginCnfLoad
 
 
@@ -943,6 +963,8 @@ CODESTARTsetModCnf
 			cs.dfltTag = (char *)es_str2cstr(pvals[i].val.d.estr, NULL);
 		} else if (!strcmp(modpblk.descr[i].name, "workaroundjournalbug")) {
 			cs.bWorkAroundJournalBug = (int) pvals[i].val.d.n;
+		} else if (!strcmp(modpblk.descr[i].name, "fsync")) {
+			cs.bFsync = (int) pvals[i].val.d.n;
 		} else {
 			dbgprintf("imjournal: program error, non-handled "
 				"param '%s' in beginCnfLoad\n", modpblk.descr[i].name);