lttng: enable-event: remove gotos from cmd_enable_event

The use of automated resource management makes it possible to remove the
numerous uses of gotos in cmd_enable_event. Replace them by simple
return statements.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Change-Id: Ic9f3207d8b1e9c5b044506e0233468230db1acd0

diff --git a/src/bin/lttng/commands/enable_events.cpp b/src/bin/lttng/commands/enable_events.cpp
index f95a006102fc23d13922f395fd74e9e82c447ad5..78cc0ea8b88f6ef8d31723312248fd7cefb0d1be 100644 (file)
--- a/src/bin/lttng/commands/enable_events.cpp
+++ b/src/bin/lttng/commands/enable_events.cpp
@@ -9,6 +9,7 @@
 #include <common/compat/getenv.hpp>
 #include <common/compat/string.hpp>
 #include <common/make-unique-wrapper.hpp>
+#include <common/scope-exit.hpp>
 #include <common/sessiond-comm/sessiond-comm.hpp>
 #include <common/string-utils/string-utils.hpp>
 #include <common/utils.hpp>
@@ -1295,7 +1296,7 @@ int cmd_enable_events(int argc, const char **argv)
                switch (opt) {
                case OPT_HELP:
                        SHOW_HELP();
-                       goto end;
+                       return CMD_SUCCESS;
                case OPT_TRACEPOINT:
                        opt_event_type = LTTNG_EVENT_TRACEPOINT;
                        break;
@@ -1324,14 +1325,13 @@ int cmd_enable_events(int argc, const char **argv)
                        break;
                case OPT_LIST_OPTIONS:
                        list_cmd_options(stdout, long_options);
-                       goto end;
+                       return CMD_SUCCESS;
                case OPT_FILTER:
                        break;
                case OPT_EXCLUDE:
                        break;
                default:
-                       ret = CMD_UNDEFINED;
-                       goto end;
+                       return CMD_UNDEFINED;
                }
 
                /* Validate event type. Multiple event type are not supported. */
@@ -1340,8 +1340,7 @@ int cmd_enable_events(int argc, const char **argv)
                } else {
                        if (event_type != opt_event_type) {
                                ERR("Multiple event type not supported.");
-                               ret = CMD_ERROR;
-                               goto end;
+                               return CMD_ERROR;
                        }
                }
        }
@@ -1349,39 +1348,66 @@ int cmd_enable_events(int argc, const char **argv)
        ret = print_missing_or_multiple_domains(
                opt_kernel + opt_userspace + opt_jul + opt_log4j + opt_python, true);
        if (ret) {
-               ret = CMD_ERROR;
-               goto end;
+               return CMD_ERROR;
        }
 
        /* Mi check */
        if (lttng_opt_mi) {
                writer = mi_writer_uptr(mi_lttng_writer_create(fileno(stdout), lttng_opt_mi));
                if (!writer) {
-                       ret = -LTTNG_ERR_NOMEM;
-                       goto end;
+                       LTTNG_THROW_ERROR(lttng::format(
+                               "Failed to create MI writer: format_code={}", lttng_opt_mi));
                }
 
                /* Open command element */
                ret = mi_lttng_writer_command_open(writer.get(),
                                                   mi_lttng_element_command_enable_event);
                if (ret) {
-                       ret = CMD_ERROR;
-                       goto end;
+                       LTTNG_THROW_ERROR(lttng::format(
+                               "Failed to open MI command element: command_name=`{}`",
+                               mi_lttng_element_command_enable_event));
                }
 
                /* Open output element */
                ret = mi_lttng_writer_open_element(writer.get(), mi_lttng_element_command_output);
                if (ret) {
-                       ret = CMD_ERROR;
-                       goto end;
+                       LTTNG_THROW_ERROR(
+                               lttng::format("Failed to open MI element: element_name=`{}`",
+                                             mi_lttng_element_command_output));
                }
        }
 
+       /* Close the MI command context when leaving the function, no matter the result. */
+       const auto close_mi_on_exit = lttng::make_scope_exit([&success]() noexcept {
+               if (!lttng_opt_mi) {
+                       return;
+               }
+
+               /* Close output element. */
+               if (mi_lttng_writer_close_element(writer.get())) {
+                       ERR_FMT("Failed to close MI output element");
+                       return;
+               }
+
+               if (mi_lttng_writer_write_element_bool(
+                           writer.get(), mi_lttng_element_command_success, success)) {
+                       ERR_FMT("Failed to write MI element: element_name=`{}`, value={}",
+                               mi_lttng_element_command_success,
+                               success);
+                       return;
+               }
+
+               /* Command element close. */
+               if (mi_lttng_writer_command_close(writer.get())) {
+                       ERR_FMT("Failed to close MI command element");
+                       return;
+               }
+       });
+
        arg_event_list = poptGetArg(pc.get());
        if (arg_event_list == nullptr && opt_enable_all == 0) {
                ERR("Missing event name(s).");
-               ret = CMD_ERROR;
-               goto end;
+               return CMD_ERROR;
        }
 
        for (std::string line; std::getline(event_list_arg_stream, line, ',');) {
@@ -1391,8 +1417,7 @@ int cmd_enable_events(int argc, const char **argv)
        leftover = poptGetArg(pc.get());
        if (leftover) {
                ERR("Unknown argument: %s", leftover);
-               ret = CMD_ERROR;
-               goto end;
+               return CMD_ERROR;
        }
 
        if (!opt_session_name) {
@@ -1400,9 +1425,7 @@ int cmd_enable_events(int argc, const char **argv)
                        lttng::make_unique_wrapper<char, lttng::free>(get_session_name());
 
                if (!rc_file_session_name) {
-                       command_ret = CMD_ERROR;
-                       success = 0;
-                       goto mi_closing;
+                       return CMD_ERROR;
                }
 
                session_name = rc_file_session_name.get();
@@ -1412,37 +1435,8 @@ int cmd_enable_events(int argc, const char **argv)
 
        command_ret = enable_events(session_name, patterns);
        if (command_ret) {
-               success = 0;
-               goto mi_closing;
-       }
-
-mi_closing:
-       /* Mi closing */
-       if (lttng_opt_mi) {
-               /* Close  output element */
-               ret = mi_lttng_writer_close_element(writer.get());
-               if (ret) {
-                       ret = CMD_ERROR;
-                       goto end;
-               }
-
-               ret = mi_lttng_writer_write_element_bool(
-                       writer.get(), mi_lttng_element_command_success, success);
-               if (ret) {
-                       ret = CMD_ERROR;
-                       goto end;
-               }
-
-               /* Command element close */
-               ret = mi_lttng_writer_command_close(writer.get());
-               if (ret) {
-                       ret = CMD_ERROR;
-                       goto end;
-               }
+               return CMD_ERROR;
        }
 
-end:
-       /* Overwrite ret if an error occurred in enable_events */
-       ret = command_ret ? command_ret : ret;
-       return ret;
+       return CMD_SUCCESS;
 }