Sample improve, exit when error happens instead of raise error #330
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graebm
reviewed
Jul 7, 2023
source/s3_list_objects.c
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| @@ -142,7 +142,7 @@ static bool s_on_list_bucket_result_node_encountered( | |||
| } | |||
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| if (ret_val && operation_data->on_object) { | |||
| ret_val |= operation_data->on_object(&fs_wrapper.fs_info, operation_data->user_data); | |||
| ret_val &= operation_data->on_object(&fs_wrapper.fs_info, operation_data->user_data); | |||
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trivial: rename ret_val -> keep_going or something, so we don't confuse it with an int again
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or just do keep_going = instead of this bitwise nonsense
samples/s3/s3-cp.c
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| return AWS_OP_ERR; | ||
| fprintf( | ||
| stderr, | ||
| "Failure when open file %s with error %s\n", |
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Suggested change
| "Failure when open file %s with error %s\n", | |
| "Failure to open file %s, error %s\n", |
source/s3_list_objects.c
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| @@ -142,7 +142,7 @@ static bool s_on_list_bucket_result_node_encountered( | |||
| } | |||
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| if (ret_val && operation_data->on_object) { | |||
| ret_val |= operation_data->on_object(&fs_wrapper.fs_info, operation_data->user_data); | |||
| ret_val &= operation_data->on_object(&fs_wrapper.fs_info, operation_data->user_data); | |||
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Have you looked into our other uses of the XML parser, in our real code, to see if we're "properly" using user_data to report errors?
Codecov Report
Additional details and impacted files@@ Coverage Diff @@
## main #330 +/- ##
==========================================
- Coverage 88.87% 88.74% -0.13%
==========================================
Files 17 17
Lines 4943 4932 -11
==========================================
- Hits 4393 4377 -16
- Misses 550 555 +5
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graebm
added a commit
to awslabs/aws-c-common
that referenced
this pull request
Jul 18, 2023
**Issue:** It's hard to report errors with the current API. Errors are being accidentally ignored, and some errors are never checked (perhaps because it was too much effort?). **Diagnosis:** The current callback returns `bool` of whether to continue parsing, rather than our typical `int/AWS_OP_SUCCESS/aws_raise_error()` [error handling](https://github.com/awslabs/aws-c-common/blob/b1ef77c1790a8776b58ae5ae57f90e9534b78991/README.md#error-handling). This seems like a simple design. But the inconsistency in return type leads to errors being [mistakenly swallowed](awslabs/aws-c-s3#330 (comment)). And it makes it hard when you do want to "bubble up" an error from the callback. Callbacks needs to store a custom `error_code` in their `user_data` to report an error. Most callbacks never bothered to do this, maybe because it was extra work? **Description of changes:** - XML traversal callback returns `int` instead of `bool`. - If a callback fails, the whole parse() fails. - You can no longer stop parsing without causing failure. But in nearly all use-cases we were stopping due to error. I found 1 case where we stopped because we found what we were looking for. But in this case, it didn't really hurt to continue parsing. The reduced complexity seemed worth the change. - Remove ~aws_xml_parser_new(), aws_xml_parser_destroy(), aws_xml_parser_parse()~, replace with `aws_xml_parse()`. - The new() and destroy() calls were unnecessary. Removing them simplifies use. - `aws_xml_node_get_name()` just returns `aws_byte_cursor()`, instead of ~int~ - This can't fail. Changing the signature simplifies use. - Raise `AWS_ERROR_INVALID_XML` instead of ~AWS_ERROR_MALFORMED_INPUT_STRING~ - This change is more wishy-washy. It seemed useful to get this new, more specific, error code if it bubbling up from deep within some larger operation, like an S3 meta-request. **API BREAK:** We don't know any external uses of this API, so it seems safe to change. The API is only intended for internal use by the aws-c libraries, which are being fixed up now. This API was quickly written as private code in aws-c-auth (awslabs/aws-c-auth#40), then moved to public in aws-c-common (#674) when aws-c-s3 also needed to parse XML. The fact that it was originally private is why this API didn't get more scrutiny originally.
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