From e74a98a6e3d6440123bcf9441f647375beb1a0a4 Mon Sep 17 00:00:00 2001
From: i-ky <gl.ivanovsky@gmail.com>
Date: Wed, 24 Apr 2019 01:10:23 +0300
Subject: [PATCH] Replace zbx_snprintf() function/macro with function pointer
 which is initialized in runtime

---
 configure.ac      |  3 +++
 src/libzbxpgsql.c | 23 +++++++++++++++++++++++
 src/libzbxpgsql.h |  4 ++++
 3 files changed, 30 insertions(+)

diff --git a/configure.ac b/configure.ac
index bd91266..a937ccd 100644
--- a/configure.ac
+++ b/configure.ac
@@ -42,6 +42,9 @@ if test ! "x$found_zabbix" = "xyes"; then
 	AC_MSG_ERROR([Zabbix headers not found])
 fi
 
+# Checking for libdl
+AC_CHECK_LIB(dl,dlopen)
+
 # output
 AC_CONFIG_FILES([
  Makefile
diff --git a/src/libzbxpgsql.c b/src/libzbxpgsql.c
index 9d2b654..1439458 100644
--- a/src/libzbxpgsql.c
+++ b/src/libzbxpgsql.c
@@ -25,6 +25,10 @@
 
 #include "libzbxpgsql.h"
 
+#include <dlfcn.h>
+
+size_t (*zbx_snprintf)(char *str, size_t count, const char *fmt, ...) = NULL;
+
 // Define custom keys
 static ZBX_METRIC keys[] =
 /*      KEY                         FLAG            FUNCTION                        TEST PARAMETERS */
@@ -180,7 +184,26 @@ int  zbx_module_uninit() {
 */
 
 int  zbx_module_init() {
+    void *handle;
+
     zabbix_log(LOG_LEVEL_INFORMATION, "starting agent module %s", PACKAGE_STRING);
+
+    if (NULL == (handle = dlopen(NULL, RTLD_LAZY | RTLD_NOLOAD)))
+    {
+        zabbix_log(LOG_LEVEL_ERR, "failed to dlopen() Zabbix binary: %s", dlerror());
+        return ZBX_MODULE_FAIL;
+    }
+
+    if (NULL == (zbx_snprintf = dlsym(handle, "zbx_snprintf")) &&
+        NULL == (zbx_snprintf = dlsym(handle, "__zbx_zbx_snprintf")))
+    {
+        zabbix_log(LOG_LEVEL_ERR, "failed to find zbx_snprintf() or __zbx_zbx_snprintf(): %s", dlerror());
+        dlclose(handle);
+        return ZBX_MODULE_FAIL;
+    }
+
+    dlclose(handle);
+
     return init_config();
 }
 
diff --git a/src/libzbxpgsql.h b/src/libzbxpgsql.h
index d1f67c3..26378d0 100644
--- a/src/libzbxpgsql.h
+++ b/src/libzbxpgsql.h
@@ -43,7 +43,11 @@
 #define HAVE_TIME_H 1
 #include <sysinc.h>
 #include <module.h>
+#define zbx_snprintf any_name_is_better /* don't want common.h to declare zbx_snprintf() function */
 #include <common.h>
+#undef zbx_snprintf /* forget macro definition from old common.h and/or our own macro definition two lines above */
+#define zbx_snprintf pgsql_snprintf /* prevent symbol conflict with zbx_snprintf() function in new Zabbix binaries */
+extern size_t (*zbx_snprintf)(char *str, size_t count, const char *fmt, ...); /* use old name to avoid changing much of our code */
 #include <log.h>
 #include <zbxjson.h>
 #include <version.h>