Fixed Stream find hang.

[NathanSweet]

Description of Change

Check timedRead is < 0, then use char (rather than int) for the rest of findMulti. This avoids sign extension and incorrect comparisons which result in a hang.

Tests scenarios

This code hangs forever, even when Serial repeatedly receives 0xCA, tested on Arduino Mega 2560 R3:

while (!Serial1.find(0xCA)) ;

The reason is in Stream findMulti:
https://github.com/espressif/arduino-esp32/blob/master/cores/esp32/Stream.cpp#L132

Consider this comparison:

if (c == t->str[t->index]) {

c is int with an unsigned value 0xCA.
t->str is const char * with (on Arduino Mega 2560 R3) a signed value -54 decimal which as an unsigned value is 0xCA.
In the comparison, the char is sign extended to an int, resulting in 0xFFFFFFCA giving:

if (0xCA == 0xFFFFFFCA) {

This is never true and not the intention. There appear to be other comparisons in Stream.cpp with this problem.

[CLAassistant]

All committers have signed the CLA.

[github-actions]

Warnings

⚠️

Some issues found for the commit messages in this PR: the commit message "Update Stream.cpp": summary looks empty type/action looks empty Please fix these commit messages - here are some basic tips: follow Conventional Commits style correct format of commit message should be: <type/action>(<scope/component>): <summary>, for example fix(esp32): Fixed startup timeout issue allowed types are: change,ci,docs,feat,fix,refactor,remove,revert,test sufficiently descriptive message summary should be between 20 to 72 characters and start with upper case letter avoid Jira references in commit messages (unavailable/irrelevant for our customers) TIP: Install pre-commit hooks and run this check when committing (uses the Conventional Precommit Linter).

👋 Hello NathanSweet, we appreciate your contribution to this project!

---

Click to see more instructions ...

This automated output is generated by the PR linter DangerJS, which checks if your Pull Request meets the project's requirements and helps you fix potential issues.

DangerJS is triggered with each push event to a Pull Request and modify the contents of this comment.

Please consider the following:
- Danger mainly focuses on the PR structure and formatting and can't understand the meaning behind your code or changes.
- Danger is not a substitute for human code reviews; it's still important to request a code review from your colleagues.
- Resolve all warnings (⚠️ ) before requesting a review from human reviewers - they will appreciate it.
- To manually retry these Danger checks, please navigate to the Actions tab and re-run last Danger workflow.

Review and merge process you can expect ...

We do welcome contributions in the form of bug reports, feature requests and pull requests.

1. An internal issue has been created for the PR, we assign it to the relevant engineer.
2. They review the PR and either approve it or ask you for changes or clarifications.
3. Once the GitHub PR is approved we do the final review, collect approvals from core owners and make sure all the automated tests are passing.
- At this point we may do some adjustments to the proposed change, or extend it by adding tests or documentation.
4. If the change is approved and passes the tests it is merged into the default branch.

Generated by 🚫 dangerJS against aa33022

[me-no-dev]

Hi @NathanSweet ! Thank you for the PR. Please note that Stream and other Arduino classes come from upstream. I suggest you propose your fix first in the official Arduino core API and when accepted, let us know so we can update it on our end.

I will close this PR for now

[NathanSweet]

@me-no-dev I looked at Stream.cpp over there and they have fixed the problem:
https://github.com/arduino/ArduinoCore-API/blob/master/api/Stream.cpp#L273
In this commit from 2018:
arduino/ArduinoCore-API@e04d90c

Why is the Arduino code in your repo so out of date?
https://github.com/espressif/arduino-esp32/blob/master/cores/esp32/Stream.cpp#L132

[me-no-dev]

Why is the Arduino code in your repo so out of date?

There are quite a few reasons why that is so. I'll update the class. Can you please post an issue, so we can track it's progress?

[me-no-dev]

Here is the update #10328

[NathanSweet]

Cool, thank you!

I didn't mean to be rude, it's just surprising to see a dependency forked and missing fixes from 6 years ago. I guess the Arduino codebase has done things that aren't agreeable with ESP32?