From 28a9e3f98407965d20597369a6059baf6db70e01 Mon Sep 17 00:00:00 2001
From: Nick Vyzas <nick@sysown.com>
Date: Thu, 30 Nov 2017 20:39:59 +0200
Subject: [PATCH] Fixes - "Event log file is overwritten on ProxySQL service
 restart" #1201

---
 lib/MySQL_Logger.cpp | 55 +++++++++++++++++++++++++++++---------------
 lib/MySQL_Thread.cpp | 27 +++++++++++++++++++---
 2 files changed, 61 insertions(+), 21 deletions(-)

diff --git a/lib/MySQL_Logger.cpp b/lib/MySQL_Logger.cpp
index 60fc3d710..e8519b29f 100644
--- a/lib/MySQL_Logger.cpp
+++ b/lib/MySQL_Logger.cpp
@@ -2,7 +2,7 @@
 #include "proxysql.h"
 #include "cpp.h"
 #include <dirent.h>
-
+#include <libgen.h>
 
 static uint8_t mysql_encode_length(uint64_t len, unsigned char *hd) {
 	if (len < 251) return 1;
@@ -206,15 +206,16 @@ void MySQL_Logger::flush_log_unlocked() {
 
 
 void MySQL_Logger::open_log_unlocked() {
-	if (log_file_id==0) {
-		log_file_id=find_next_id()+1;
+        log_file_id=find_next_id();
+	if (log_file_id!=0) {
+                log_file_id=find_next_id()+1;
 	} else {
-		log_file_id++;
+                log_file_id++;
 	}
 	char *filen=NULL;
 	if (base_filename[0]=='/') { // absolute path
 		filen=(char *)malloc(strlen(base_filename)+10);
-		sprintf(filen,"/%s.%08d",base_filename,log_file_id);
+		sprintf(filen,"%s.%08d",base_filename,log_file_id);
 	} else { // relative path
 		filen=(char *)malloc(strlen(datadir)+strlen(base_filename)+10);
 		sprintf(filen,"%s/%s.%08d",datadir,base_filename,log_file_id);
@@ -343,26 +344,44 @@ unsigned int MySQL_Logger::find_next_id() {
 	int maxidx=0;
 	DIR *dir;
 	struct dirent *ent;
+	char *eval_filename = NULL;
+	char *eval_dirname = NULL;
+        char *eval_pathname = NULL;
 	assert(base_filename);
-	assert(datadir);
-	size_t bfl=strlen(base_filename);
-	if ((dir = opendir(datadir)) != NULL) {
-	  while ((ent = readdir (dir)) != NULL) {
-			if (strlen(ent->d_name)==bfl+9) {
-				if (strncmp(ent->d_name,base_filename,bfl)==0) {
-					if (ent->d_name[bfl]=='.') {
-						int idx=atoi(ent->d_name+bfl+1);
+	if (base_filename[0] == '/') {
+		eval_pathname = strdup(base_filename);
+		eval_filename = basename(eval_pathname);
+		eval_dirname = dirname(eval_pathname);
+	} else {
+                assert(datadir);
+		eval_filename = strdup(base_filename);
+		eval_dirname = strdup(datadir);
+	}
+	size_t efl=strlen(eval_filename);
+	if ((dir = opendir(eval_dirname)) != NULL) {
+		while ((ent = readdir (dir)) != NULL) {
+			if (strlen(ent->d_name)==efl+9) {
+				if (strncmp(ent->d_name,eval_filename,efl)==0) {
+					if (ent->d_name[efl]=='.') {
+						int idx=atoi(ent->d_name+efl+1);
 						if (idx>maxidx) maxidx=idx;
 					}
 				}
 			}
 		}
-  closedir (dir);
-	return maxidx;
+		closedir (dir);
+		if (base_filename[0] != '/') {
+			free(eval_dirname);
+			free(eval_filename);
+		}
+                if (eval_pathname) {
+                        free(eval_pathname);
+                }
+		return maxidx;
 	} else {
-  /* could not open directory */
-		fprintf(stderr,"Unable to open datadir: %s\n", datadir);
+        /* could not open directory */
+		proxy_error("Unable to open datadir: %s\n", eval_dirname);
 		exit(EXIT_FAILURE);
-	}
+	}        
 	return 0;
 }
diff --git a/lib/MySQL_Thread.cpp b/lib/MySQL_Thread.cpp
index 5a8931ef7..0d4aaddd0 100644
--- a/lib/MySQL_Thread.cpp
+++ b/lib/MySQL_Thread.cpp
@@ -4,6 +4,8 @@
 #include "cpp.h"
 #include "MySQL_Thread.h"
 #include "SpookyV2.h"
+#include <dirent.h>
+#include <libgen.h>
 
 #ifdef DEBUG
 MySQL_Session *sess_stopat;
@@ -1693,9 +1695,28 @@ bool MySQL_Threads_Handler::set_variable(char *name, char *value) {	// this is t
 	}
 
 	if (!strcasecmp(name,"eventslog_filename")) {
-		free(variables.eventslog_filename);
-		variables.eventslog_filename=strdup(value);
-		return true;
+                if (value[strlen(value) - 1] == '/') {
+                        proxy_error("%s is an invalid value for eventslog_filename, please specify a filename not just the path\n", value);
+			return false;
+		} else if (value[0] == '/') {
+			char *full_path = strdup(value);
+                        char *eval_dirname = dirname(full_path);
+                        DIR* eventlog_dir = opendir(eval_dirname);
+			free(full_path);
+                        if (eventlog_dir) {
+				closedir(eventlog_dir);
+				free(variables.eventslog_filename);
+				variables.eventslog_filename=strdup(value);
+                                return true;
+			} else {
+				proxy_error("%s is an invalid value for eventslog_filename path, the directory cannot be accessed\n", eval_dirname);
+				return false;
+			}
+		} else {
+			free(variables.eventslog_filename);
+			variables.eventslog_filename=strdup(value);
+			return true;
+		}
 	}
 	if (!strcasecmp(name,"server_capabilities")) {
 		int intv=atoi(value);