[onert] Add API function for retrieving last error message by arkq · Pull Request #16282 · Samsung/ONE

arkq · 2025-11-12T15:17:28Z

This PR adds dedicated API function nnfw_get_last_error_message() for retrieving last error message in case when other functions return status code other than NNFW_STATUS_NO_ERROR.

It also does small refactoring in order to properly set last error message in all API calls which includes:

Refactoring of the loadModel() helper so it will not print to std:cerr
Refactoring Session::deprecated function to be non-static to allow setting last error message in it
Moving getTensorIndexImpl() helper to be a private member of Session to allow setting last error message in it
Testing deprecated APIs with a correct session instance instead of NULL

Also this PR adds small check in the ValidationTestSessionCreated.neg_load_session_2 test case to verify nnfw_get_last_error_message() API correctness.

This PR is fix for one of the issues diagnosed in #16102 (comment)

ONE-DCO-1.0-Signed-off-by: Arkadiusz Bokowy a.bokowy@samsung.com

arkq · 2025-11-18T14:46:11Z

Small info how this change will be used.

If approved, it will be possible to get proper error message string in the python binding as follows:

--- a/runtime/onert/api/python/src/wrapper/nnfw_api_wrapper.cc
+++ b/runtime/onert/api/python/src/wrapper/nnfw_api_wrapper.cc
@@ -24,27 +24,26 @@ namespace onert::api::python
 
 namespace py = pybind11;
 
-void ensure_status(NNFW_STATUS status)
+void NNFW_SESSION::ensure_status(NNFW_STATUS status)
 {
   switch (status)
   {
     case NNFW_STATUS::NNFW_STATUS_NO_ERROR:
       return;
     case NNFW_STATUS::NNFW_STATUS_ERROR:
-      throw NnfwError("NNFW_STATUS_ERROR");
+      throw NnfwError(nnfw_get_last_error_message(session));
     case NNFW_STATUS::NNFW_STATUS_UNEXPECTED_NULL:
-      throw NnfwUnexpectedNullError("NNFW_STATUS_UNEXPECTED_NULL");
+      throw NnfwUnexpectedNullError(nnfw_get_last_error_message(session));
     case NNFW_STATUS::NNFW_STATUS_INVALID_STATE:
-      throw NnfwInvalidStateError("NNFW_STATUS_INVALID_STATE");
+      throw NnfwInvalidStateError(nnfw_get_last_error_message(session));
     case NNFW_STATUS::NNFW_STATUS_OUT_OF_MEMORY:
-      throw NnfwOutOfMemoryError("NNFW_STATUS_OUT_OF_MEMORY");
+      throw NnfwOutOfMemoryError(nnfw_get_last_error_message(session));
     case NNFW_STATUS::NNFW_STATUS_INSUFFICIENT_OUTPUT_SIZE:
-      throw NnfwInsufficientOutputError("NNFW_STATUS_INSUFFICIENT_OUTPUT_SIZE");
+      throw NnfwInsufficientOutputError(nnfw_get_last_error_message(session));
     case NNFW_STATUS::NNFW_STATUS_DEPRECATED_API:
-      throw NnfwDeprecatedApiError("NNFW_STATUS_DEPRECATED_API");
-    default:
-      throw NnfwError("NNFW_UNKNOWN_ERROR");
+      throw NnfwDeprecatedApiError(nnfw_get_last_error_message(session));
   }
+  throw NnfwError(nnfw_get_last_error_message(session));
 }
 
 NNFW_LAYOUT getLayout(const char *layout)

Copilot

Pull request overview

This PR introduces a new API function nnfw_get_last_error_message() to retrieve error messages from failed API calls, replacing the previous approach of writing errors to std::cerr. The implementation includes comprehensive refactoring to set appropriate error messages in all API functions using a new _last_error_message member variable in the Session class.

Adds nnfw_get_last_error_message() API function for retrieving last error message
Refactors error handling throughout Session methods to use setLastErrorMessage() instead of std::cerr
Converts deprecated API functions from static to instance methods to enable error message tracking

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
runtime/onert/api/nnfw/include/nnfw.h	Adds public API declaration for `nnfw_get_last_error_message()`
runtime/onert/api/nnfw/src/APIImpl.cc	Implements `nnfw_get_last_error_message()` and updates deprecated API wrappers to use instance methods
runtime/onert/api/nnfw/src/Session.h	Adds `_last_error_message` member, `get_last_error_message()`, `setLastErrorMessage()` methods, and moves `getTensorIndexImpl()` to private
runtime/onert/api/nnfw/src/Session.cc	Refactors all API methods to call `setLastErrorMessage()` for error conditions and removes `std::cerr` writes; refactors `loadModel()` helper to throw exceptions
runtime/tests/nnfw_api/src/NNPackageTests/SessionCreated.test.cc	Adds test for error message retrieval and moves deprecated API tests from SingleSession
runtime/tests/nnfw_api/src/NNPackageTests/SingleSession.test.cc	Removes deprecated API tests (moved to SessionCreated)

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runtime/onert/api/nnfw/include/nnfw.h

runtime/onert/api/nnfw/src/Session.cc

runtime/onert/api/nnfw/src/APIImpl.cc

arkq · 2025-11-26T13:17:30Z

@hseok-oh Could you please take a look as this and let me know what do you think? If you like such approach (new API for getting the last error message) I can split that PR into smaller PRs (if you prefer very narrow PRs in terms of scope of changes). Basically, I will submit every commit from this draft as a separate PR.

There is one thing that you should look at, though. The signature of this new API is as follows: nnfw_get_last_error_message(nnfw_session *session). There are some pros and cons with such approach:

pros:

every session has its own error message, so one can simultaneously run more than one session and the error message will not be lost
in multi threaded application, the error message can be retrieved on a different thread

cons:

since we need valid session pointer, this function can not get the error message in case of the nnfw_create_session() failure

Other approach is to hold the error message in the static variable (preferably in the thread local variable) just like the errno value. However, such nnfw_get_last_error_message(void) will be different than the rest of the API calls (every function takes the session pointer as an argument). Also, in multi session scenario on will have to get the error just after every API call. There are also other possibilities, like extending variety of error values, so every single failure will have its own error value (the way openssl does it). Or we can add new API for session creation, something like nnfw_create_session_with_error_message(nnfw_session **session, const char **errmsg) where user can optionally pass an address to a pointer where the static error message will be stored. Anyway, there are only two viable reasons why nnfw_get_last_error_message might fail: 1) passed NULL as session; 2) memory allocation failure. So, the status code should be good enough, just as it is right now.

arkq · 2026-01-27T10:22:46Z

@glistening could you please look at this draft and checks whether the direction of these changes is right? If so I will split that draft into separate PR (one commit per PR) to simplify the review of particular changes (there are some prerequisites/cleanups required before the core change can be merged).

glistening · 2026-01-27T10:46:16Z

@arkq I am okay for this change. Also, it looks okay not to split this PR. Just swith to "Ready for review" to get other's opinion.

cc @Samsung/one_onert

hseok-oh · 2026-01-29T01:20:44Z

I prefer to use parameter instead of pointer return to return message string: NNFW_STATUS nnfw_get_last_error_message(nnfw_session *session, char* message_buffer, uint32_t buffer_size)

Copilot

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 6 comments.

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runtime/onert/api/nnfw/src/Session.cc

runtime/onert/api/nnfw/src/Session.h

runtime/onert/api/nnfw/src/Session.cc

runtime/onert/api/nnfw/include/nnfw.h

hseok-oh · 2026-02-02T05:37:15Z

runtime/onert/api/nnfw/src/Session.cc

+  {
+    return NNFW_STATUS_INSUFFICIENT_OUTPUT_SIZE;
+  }
+  strcpy(buffer, _last_error_message.c_str());


Please use strlcpy(buffer, _last_error_message.c_str(), length) instead of strcpy

The strlcpy is a BSD extension and I can not see any prior usage of strlcpy in this repository. Using strlcpy will require linking with libbsd. Should I add libbsd as a dependency to this project?

Hmm. Then please use strncpy such as copilot suggested. Runtime does not allow to use strcpy. (SVACE will complain this function)

OK, replaced with strncpy to hopefully satisfy SVACE.

hseok-oh

Please check my comment. Others looks good.

hseok-oh

LGTM

hseok-oh

I found this PR includes some different features

Fix GCC 15 build fail: #16356
Move unittest: ValidationTestSessionCreated.neg_deprecated_api

arkq · 2026-02-04T08:41:50Z

Fix GCC 15 build fail: #16356

Upps... sorry... I've messed the last rebase :/ I'm using Ubuntu 25.10, so without that change I'm not able to test anything...

ONE-DCO-1.0-Signed-off-by: Arkadiusz Bokowy <a.bokowy@samsung.com>

This commit adds dedicated API function nnfw_get_last_error_message() for retrieving last error message in case when other functions return status code other than NNFW_STATUS_NO_ERROR. ONE-DCO-1.0-Signed-off-by: Arkadiusz Bokowy <a.bokowy@samsung.com>

arkq · 2026-02-04T10:00:35Z

Move unittest: ValidationTestSessionCreated.neg_deprecated_api

@hseok-oh Should I create a separate PR for that? Because it seems that the ValidationTestSessionCreated.neg_deprecated_api is in the wrong file. The file is named SingleSession.test.cc and every test case except neg_deprecated_api is in the ValidationTestSingleSession group. Test cases in ValidationTestSessionCreated group are in the SessionCreated.test.cc file.

glistening · 2026-02-05T05:14:54Z

runtime/onert/api/nnfw/src/Session.cc

+
+  if (!null_terminating(tensorname, MAX_TENSOR_NAME_LENGTH))
+  {
+    setLastErrorMessage("Error during Session::getTensorIndexImpl : tensorname is too long");


You fixed the wrong error message. 👍

glistening

LGTM for last error message. Moving unrelated changes to separate PR seems done.

hseok-oh · 2026-02-06T06:35:30Z

@arkq IMO, the group name for deprecated function is invalid: ValidationTestSessionCreated -> ValidationTestSingleSession

arkq requested a review from Copilot November 25, 2025 08:38

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arkq force-pushed the session-last-error-message branch from 5659a81 to f63a698 Compare November 26, 2025 11:57

arkq marked this pull request as ready for review January 27, 2026 10:52

arkq force-pushed the session-last-error-message branch from f63a698 to fe6b56c Compare January 29, 2026 11:04

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arkq force-pushed the session-last-error-message branch from fe6b56c to 9fabc7b Compare January 29, 2026 12:01

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arkq force-pushed the session-last-error-message branch from 9fabc7b to 5df1e83 Compare February 3, 2026 07:47

hseok-oh approved these changes Feb 4, 2026

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arkq added 2 commits February 4, 2026 09:46

Refactor loadModel helper so it will not print to stderr

21dbdb2

ONE-DCO-1.0-Signed-off-by: Arkadiusz Bokowy <a.bokowy@samsung.com>

Add getTensorIndexImpl as a private member of Session

e00851e

ONE-DCO-1.0-Signed-off-by: Arkadiusz Bokowy <a.bokowy@samsung.com>

arkq force-pushed the session-last-error-message branch from 5df1e83 to 756de40 Compare February 4, 2026 08:50

arkq added 2 commits February 4, 2026 10:58

Refactor Session::deprecated function to be non-static

897d08e

ONE-DCO-1.0-Signed-off-by: Arkadiusz Bokowy <a.bokowy@samsung.com>

arkq force-pushed the session-last-error-message branch from 756de40 to 47ed86b Compare February 4, 2026 09:59

glistening reviewed Feb 5, 2026

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glistening approved these changes Feb 5, 2026

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hseok-oh approved these changes Feb 6, 2026

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hseok-oh merged commit 8c030c9 into Samsung:master Feb 6, 2026
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arkq deleted the session-last-error-message branch February 6, 2026 06:36

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