Replace zbx_snprintf() function/macro with function pointer which is …

…initialized in runtime

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

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();
 }
 

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>