Enable logger in proxy lib

src/proxy_lib/proxy_lib.c

@@ -107,6 +107,7 @@ static __TLS int was_called_from_umfPool = 0;
 /*****************************************************************************/
 
 void proxy_lib_create_common(void) {
+    util_log_init();
     umf_os_memory_provider_params_t os_params =
         umfOsMemoryProviderParamsDefault();
     umf_result_t umf_result;

src/utils/utils_log.c

@@ -254,10 +254,10 @@ void util_log_init(void) {
 
         memcpy(file, arg, len);
         file[len] = '\0';
-        loggerConfig.output = fopen(file, "w+");
+        loggerConfig.output = fopen(file, "a");
         if (!loggerConfig.output) {
             loggerConfig.output = stderr;
-            LOG_ERR("Cannot open output file %s - logging disabled", file);
+            LOG_PERR("Cannot open output file %s - logging disabled", file);
             loggerConfig.output = NULL;
             return;
         }

test/utils/utils_log.cpp

@@ -14,7 +14,7 @@ int fopen_count = 0;
 FILE *mock_fopen(const char *filename, const char *mode) {
     fopen_count++;
     EXPECT_STREQ(filename, expected_filename.c_str());
-    EXPECT_STREQ(mode, "w+");
+    EXPECT_STREQ(mode, "a");
     return MOCK_FILE_PTR;
 }