Delete the copy constructor and copy assignment operators for StaticJsonBufferBase. #524
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…sonBufferBase. These are always invalid, regardless of usage of objects created in the buffer(s). The root of the problem with using the default copy operators is that the `_buffer` pointer is copied as well, which means that the copied-to buffer now points to the copied-from buffer's memory. Consider the clearing example at the bottom of https://bblanchon.github.io/ArduinoJson/faq/how-to-reuse-a-jsonbuffer/ ``` StaticJsonBuffer<200> buf{}; JsonObject& obj = buf.createObject(); // Use obj, etc. buf = StaticJsonBuffer<200>(); // StaticJsonBufferBase::_buffer points to deallocated memory of the temporary JsonObject& new_obj = buf.createObject(); // Even if I never touch `obj` again, new_obj can easily become corrupted. ``` Copy-assignment could be easily overloaded to be correct, by simply copying everything but the `_buffer` pointer. But a properly implemented copy constructor will have to be provided by the concrete buffer types (e.g. `StaticJsonBuffer`) and call `StaticJsonBufferBase`s public constructor with the right capacity and `char*` pointer.
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You're right 😲 Don't bother with the pull request, I'll fix that myself. Thank you very much 👍 |
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These are always invalid, regardless of usage of objects created in the
buffer(s). The root of the problem with using the default copy operators is that
the
_bufferpointer is copied as well, which means that the copied-to buffernow points to the copied-from buffer's memory.
Consider the clearing example at the bottom of
https://arduinojson.org/faq/how-to-reuse-a-jsonbuffer/
Properly implemented copy operators will have to be provided by the concrete
buffer types (e.g.
StaticJsonBuffer) and something sensible needs to bedone about mis-matched capacities.