--- rsyslog-8.2102.0/action.c	2021-02-15 12:06:16.000000000 +0100

+++ rsyslog-8.2102.0-changes/action.c	2022-03-08 15:55:33.989525382 +0100

@@ -198,6 +198,7 @@

 	{ "name", eCmdHdlrGetWord, 0 }, /* legacy: actionname */

 	{ "type", eCmdHdlrString, CNFPARAM_REQUIRED }, /* legacy: actionname */

 	{ "action.errorfile", eCmdHdlrString, 0 },

+	{ "action.errorfile.maxsize", eCmdHdlrInt, 0 },

 	{ "action.writeallmarkmessages", eCmdHdlrBinary, 0 }, /* legacy: actionwriteallmarkmessages */

 	{ "action.execonlyeverynthtime", eCmdHdlrInt, 0 }, /* legacy: actionexeconlyeverynthtime */

 	{ "action.execonlyeverynthtimetimeout", eCmdHdlrInt, 0 }, /* legacy: actionexeconlyeverynthtimetimeout */

@@ -400,6 +401,8 @@

 	pThis->iResumeRetryCount = 0;

 	pThis->pszName = NULL;

 	pThis->pszErrFile = NULL;

+	pThis->maxErrFileSize = 0;

+	pThis->errFileWritten = 0;	

 	pThis->pszExternalStateFile = NULL;

 	pThis->fdErrFile = -1;

 	pThis->bWriteAllMarkMsgs = 1;

@@ -1436,6 +1439,12 @@

 				pThis->pszName, pThis->pszErrFile);

 			goto done;

 		}

+		struct stat statbuf;

+		if (fstat(pThis->fdErrFile, &statbuf) == -1) {

+			LogError(errno, RS_RET_ERR, "failed to fstat %s", pThis->pszErrFile);

+			goto done;

+		}

+		pThis->errFileWritten += statbuf.st_size;

 	}

 	for(int i = 0 ; i < nparams ; ++i) {

@@ -1454,16 +1463,26 @@

 		char *const rendered = strdup((char*)fjson_object_to_json_string(etry));

 		if(rendered == NULL)

 			goto done;

-		const size_t toWrite = strlen(rendered) + 1;

-		/* note: we use the '\0' inside the string to store a LF - we do not

-		 * otherwise need it and it safes us a copy/realloc.

-		 */

-		rendered[toWrite-1] = '\n'; /* NO LONGER A STRING! */

-		const ssize_t wrRet = write(pThis->fdErrFile, rendered, toWrite);

-		if(wrRet != (ssize_t) toWrite) {

-			LogError(errno, RS_RET_IO_ERROR,

-				"action %s: error writing errorFile %s, write returned %lld",

-				pThis->pszName, pThis->pszErrFile, (long long) wrRet);

+		size_t toWrite = strlen(rendered) + 1;

+		// Check if need to truncate the amount of bytes to write

+		if (pThis->maxErrFileSize > 0) {

+			if (pThis->errFileWritten + toWrite > pThis->maxErrFileSize) {

+				// Truncate to the pending available

+				toWrite = pThis->maxErrFileSize - pThis->errFileWritten;

+			}

+			pThis->errFileWritten += toWrite;

+		}

+		if(toWrite > 0) {

+			/* note: we use the '\0' inside the string to store a LF - we do not

+			 * otherwise need it and it safes us a copy/realloc.

+			 */

+			rendered[toWrite-1] = '\n'; /* NO LONGER A STRING! */

+			const ssize_t wrRet = write(pThis->fdErrFile, rendered, toWrite);

+			if(wrRet != (ssize_t) toWrite) {

+				LogError(errno, RS_RET_IO_ERROR,

+					"action %s: error writing errorFile %s, write returned %lld",

+					pThis->pszName, pThis->pszErrFile, (long long) wrRet);

+			}

 		}

 		free(rendered);

@@ -2048,6 +2067,8 @@

 			continue; /* this is handled seperately during module select! */

 		} else if(!strcmp(pblk.descr[i].name, "action.errorfile")) {

 			pAction->pszErrFile = es_str2cstr(pvals[i].val.d.estr, NULL);

+		} else if(!strcmp(pblk.descr[i].name, "action.errorfile.maxsize")) {

+			pAction->maxErrFileSize = pvals[i].val.d.n;

 		} else if(!strcmp(pblk.descr[i].name, "action.externalstate.file")) {

 			pAction->pszExternalStateFile = es_str2cstr(pvals[i].val.d.estr, NULL);

 		} else if(!strcmp(pblk.descr[i].name, "action.writeallmarkmessages")) {

--- rsyslog-8.2102.0-ori/action.h	2020-10-03 19:06:47.000000000 +0200

+++ rsyslog-8.2102.0-changes/action.h	2022-03-04 11:36:47.024588972 +0100

@@ -77,6 +77,8 @@

 	/* error file */

 	const char *pszErrFile;

 	int fdErrFile;

+	size_t maxErrFileSize;

+	size_t errFileWritten;

 	pthread_mutex_t mutErrFile;

 	/* external stat file system */

 	const char *pszExternalStateFile;

--- rsyslog-8.2102.0-ori/tests/Makefile.am	2021-02-15 12:06:16.000000000 +0100

+++ rsyslog-8.2102.0-changes/tests/Makefile.am	2022-03-04 11:38:01.625095709 +0100

@@ -695,7 +695,8 @@

 	mysql-actq-mt.sh \

 	mysql-actq-mt-withpause.sh \

 	action-tx-single-processing.sh \

-	action-tx-errfile.sh

+	action-tx-errfile.sh \

+	action-tx-errfile-maxsize.sh

 mysql-basic.log: mysqld-start.log

 mysql-basic-cnf6.log: mysqld-start.log

@@ -2156,6 +2157,8 @@

 	sndrcv_omudpspoof_nonstdpt.sh \

 	sndrcv_gzip.sh \

 	action-tx-single-processing.sh \

+	omfwd-errfile-maxsize.sh \

+	action-tx-errfile-maxsize.sh \

 	action-tx-errfile.sh \

 	testsuites/action-tx-errfile.result \

 	pipeaction.sh \

--- rsyslog-8.2102.0-ori/tests/omfwd-errfile-maxsize.sh	1970-01-01 01:00:00.000000000 +0100

+++ rsyslog-8.2102.0-changes/tests/omfwd-errfile-maxsize.sh	2022-03-04 11:39:02.060506234 +0100

@@ -0,0 +1,17 @@

+#!/bin/bash

+# part of the rsyslog project, released under ASL 2.0

+. ${srcdir:=.}/diag.sh init

+

+export MAX_ERROR_SIZE=1999

+

+generate_conf

+add_conf '

+action(type="omfwd" target="1.2.3.4" port="1234" Protocol="tcp" NetworkNamespace="doesNotExist"

+       action.errorfile="'$RSYSLOG2_OUT_LOG'" action.errorfile.maxsize="'$MAX_ERROR_SIZE'")

+'

+startup

+shutdown_when_empty

+wait_shutdown

+check_file_exists ${RSYSLOG2_OUT_LOG}

+file_size_check ${RSYSLOG2_OUT_LOG} ${MAX_ERROR_SIZE}

+exit_test

--- rsyslog-8.2102.0-ori/tests/action-tx-errfile-maxsize.sh	1970-01-01 01:00:00.000000000 +0100

+++ rsyslog-8.2102.0-changes/tests/action-tx-errfile-maxsize.sh	2022-03-04 11:59:22.592796989 +0100

@@ -0,0 +1,35 @@

+#!/bin/bash

+# part of the rsyslog project, released under ASL 2.0

+

+. ${srcdir:=.}/diag.sh init

+

+export NUMMESSAGES=50 # enough to generate big file

+export MAX_ERROR_SIZE=100

+

+generate_conf

+add_conf '

+$ModLoad ../plugins/ommysql/.libs/ommysql

+global(errormessagestostderr.maxnumber="5")

+

+template(type="string" name="tpl" string="insert into SystemEvents (Message, Facility) values (\"%msg%\", %$!facility%)" option.sql="on")

+

+if((not($msg contains "error")) and ($msg contains "msgnum:")) then {

+	set $.num = field($msg, 58, 2);

+	if $.num % 2 == 0 then {

+		set $!facility = $syslogfacility;

+	} else {

+		set $/cntr = 0;

+	}

+	action(type="ommysql" name="mysql_action_errfile_maxsize" server="127.0.0.1" template="tpl"

+	       db="'$RSYSLOG_DYNNAME'" uid="rsyslog" pwd="testbench" action.errorfile="'$RSYSLOG2_OUT_LOG'" action.errorfile.maxsize="'$MAX_ERROR_SIZE'")

+}

+'

+mysql_prep_for_test

+startup

+injectmsg

+shutdown_when_empty

+wait_shutdown

+mysql_get_data

+check_file_exists ${RSYSLOG2_OUT_LOG}

+file_size_check ${RSYSLOG2_OUT_LOG} ${MAX_ERROR_SIZE}

+exit_test

--- rsyslog-8.2102.0/tests/omfwd-errfile-maxsize-filled.sh	1970-01-01 01:00:00.000000000 +0100

+++ rsyslog-8.2102.0-changes/tests/omfwd-errfile-maxsize-filled.sh	2022-03-08 16:24:01.174365289 +0100

@@ -0,0 +1,19 @@

+#!/bin/bash

+# part of the rsyslog project, released under ASL 2.0

+. ${srcdir:=.}/diag.sh init

+ERRFILE=$(mktemp)

+export MAX_ERROR_SIZE=1999

+export INITIAL_FILE_SIZE=$((MAX_ERROR_SIZE - 100))

+dd if=/dev/urandom of=${ERRFILE}  bs=1 count=${INITIAL_FILE_SIZE}

+generate_conf

+add_conf '

+action(type="omfwd" target="1.2.3.4" port="1234" Protocol="tcp" NetworkNamespace="doesNotExist"

+       action.errorfile="'$ERRFILE'" action.errorfile.maxsize="'$MAX_ERROR_SIZE'")

+'

+startup

+shutdown_when_empty

+wait_shutdown

+check_file_exists ${ERRFILE}

+file_size_check ${ERRFILE} ${MAX_ERROR_SIZE}

+exit_test

+rm ${ERRFILE}