app: return dynamicatty allocated string if too long

src/cfg.c

@@ -121,6 +121,20 @@ cfg_gets(const char *param)
 	return val;
 }
 
+char *
+cfg_gets_dynamic(const char *param)
+{
+	cfg_get(param);
+	if (lua_isnil(tarantool_L, -1))
+		return NULL;
+	const char *str = lua_tostring(tarantool_L, -1);
+	size_t size = strlen(str) + 1;
+	char *res = xmalloc(size);
+	memcpy(res, str, size);
+	lua_pop(tarantool_L, 1);
+	return res;
+}
+
 double
 cfg_getd(const char *param)
 {

src/cfg.h

@@ -71,6 +71,14 @@ cfg_geti64(const char *param);
 const char *
 cfg_gets(const char *param);
 
+/**
+ * Returns a dynamically allocated string. Unlike the result of cfg_gets(), the
+ * result of this function should be freed. This string may be longer than
+ * MAX_OPT_VAL_LEN.
+ */
+char *
+cfg_gets_dynamic(const char *param);
+
 double
 cfg_getd(const char *param);
 

src/main.cc

@@ -362,7 +362,7 @@ load_cfg(void)
 	if (work_dir != NULL && chdir(work_dir) == -1)
 		panic_syserror("can't chdir to `%s'", work_dir);
 
-	const char *username = cfg_gets("username");
+	char *username = cfg_gets_dynamic("username");
 	if (username != NULL) {
 		if (getuid() == 0 || geteuid() == 0) {
 			struct passwd *pw;
@@ -387,6 +387,7 @@ load_cfg(void)
 				  username);
 		}
 	}
+	free(username);
 
 	if (cfg_geti("coredump")) {
 		struct rlimit c = { 0, 0 };