BLERemoteCharacteristic writeValue fails to write std::strings containing null character '\0'

[snosrap]

Unlike C-style strings, std::strings can contain the null character. For example std::string("hello\0world").

However, in BLERemoteCharacteristic.cpp, the std::string newValue is converted to a C-style string before being sent to writeValue. This means that any characters after a null character in newValue will not be sent to writeValue. For example, std::string("hello\0world") will be converted into the C-style/null-terminated string "hello\0".

arduino-esp32/libraries/BLE/src/BLERemoteCharacteristic.cpp

Line 538 in f7fb006

writeValue((uint8_t*)newValue.c_str(), strlen(newValue.c_str()), response);

A fix would be to use the data() method on std::string and, more importantly, the length() method on std::string. newValue.length() will give the total length of the string (including any null characters), however strlen will only return the length up to the first null character.

void BLERemoteCharacteristic::writeValue(std::string newValue, bool response) {
	writeValue((uint8_t*)newValue.data(), newValue.length(), response);
} // writeValue

[chegewara]

https://github.com/espressif/arduino-esp32/blob/master/libraries/BLE/src/BLERemoteCharacteristic.h#L50

[snosrap]

@chegewara, I'm not sure I understand your comment. Are you suggesting I not use writeValue(std::string newValue, bool response = false) in cases where newValue may contain null characters?

[chegewara]

Sorry, i didnt read carefully your OP. Yes, this change is good.