Handle incomplete errors when parsing escaped string sequences

[nirosys]

Issue #, if available: #494

Description of changes:
This PR adds two changes:

1. Updates error handling while parsing escaped string sequences in order to bubble up nom's Incomplete errors to the reader, so that they can be communicated further.
2. Updates read_from to ensure that the amount of data read is limited to the length provided by the caller. Prior to this PR the entire rest of the buffer would be used for reading data. While this could be beneficial (the memory is allocated, using it makes sense) the caller expects to read no more than length, so as a matter of correctness we shouldn't read more than length.

A regression test was also added to mimic the behavior seen in #494.

---

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[popematt]

Am I understanding this correctly? These lines are testing that you can append more data and have the parsing continue successfully, right? If so, it's probably a good idea to assert that we are getting the expected value, not just the expected type.

[nirosys]

Yea, I could add that. The primary purpose of the unit test though is to ensure the incomplete error is returned, since that is what the PR is changing. There are other unit tests that validate the parser's behavior when continuing from an incomplete, so imo the append_bytes, and next_type, could even be removed.

This test might be better off testing the escaped sequence (or string) parser directly rather than the reader.

[codecov]

Codecov Report

Patch coverage: 94.57% and project coverage change: +0.04 🎉

Comparison is base (6a05f30) 89.56% compared to head (3655857) 89.60%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #495      +/-   ##
==========================================
+ Coverage   89.56%   89.60%   +0.04%     
==========================================
  Files          80       82       +2     
  Lines       13951    14044      +93     
==========================================
+ Hits        12495    12584      +89     
- Misses       1456     1460       +4     

Impacted Files	Coverage Δ
src/binary/non_blocking/raw_binary_reader.rs	81.79% <ø> (ø)
src/stream_reader.rs	100.00% <ø> (ø)
src/system_reader.rs	85.42% <ø> (ø)
src/element/mod.rs	89.55% <71.42%> (+0.12%)	⬆️
src/text/non_blocking/raw_text_reader.rs	89.34% <80.00%> (-0.17%)	⬇️
src/binary/raw_binary_reader.rs	90.90% <100.00%> (ø)
src/binary/raw_binary_writer.rs	94.78% <100.00%> (+0.01%)	⬆️
src/element/bytes.rs	100.00% <100.00%> (ø)
src/element/element_stream_reader.rs	86.50% <100.00%> (ø)
src/element/lob.rs	100.00% <100.00%> (ø)
... and 6 more

... and 1 file with indirect coverage changes

Help us with your feedback. Take ten seconds to tell us how you rate us. Have a feature suggestion? Share it here.

☔ View full report in Codecov by Sentry.
📢 Do you have feedback about the report comment? Let us know in this issue.