Fix serial monitor output cut short with multibyte (UTF-8) data #9809
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Also, I realize that this is a performance-critical bit of code (there has been quite some testing in the past to ensure that high-bandwidth serial streams from native USB boards are properly handled), but I think none of these changes are significant in that sense (the process is still the same, except that in some cases, there might be one extra loop to process any leftover data). Also note that the |
facchinm
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Component: IDE Serial monitor
This makes the code slightly more compact and easier to read.
This fixes a problem with the Serial UTF-8 decoder. This decoding moves data from char[] buf, into a ByteBuffer inFromSerial, then decodes them into a CharBuffer outToMessage and converts to a char[] to pass on. When the buf read contained just over a full buffer worth of bytes and contained some multi-byte characters, a situation could arise where two decodes were needed to fill up outToMessage, leaving some data in inFromSerial. If in this case no data would be left in buf, decoding would stop until more data came in from serial. This commit fixes this problem by: - Changing the outer loop to continue running when buf is empty, but inFromSerial is not. - Changing the inner loop to run at least once (so it runs when buf is empty, but inFromSerial is no). - Breaking out of the outer loop when no characters were produced (this handles the case where only an incomplete UTF-8 character remains in inFromSerial, which would otherwise prevent the loop from terminating. - Removes a `if (outToMessage.hasRemaining()` check that is now necessarily true if the break was not done. This fixes arduino#9808.
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I've added the missing unit test, the patch LGTM, I'll merge as soon as the CI pass. |
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✅ Build completed. Please test this code using one of the following: ⬇️ https://downloads.arduino.cc/javaide/pull_requests/arduino-PR-9809-BUILD-936-linux32.tar.xz ℹ️ The |
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Test looks good, thanks! |
This fixes #9808, detailed description in the commit messages.
This seems like a class that could use some automated testing, but I did not see any existing tests (none at all in arduino-core, only in app), nor did I find any meaningful documentation about how to run tests (I only found "ant test", which runs all tests and does not show a useful summary to tell if any tests failed AFAICS). Hence, no tests.