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Ensure that _size is properly set in begin #2706

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Merged
merged 3 commits into from
Apr 26, 2019
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Ensure that _size is properly set in begin #2706

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Ensure that _size is properly set in begin
lbernstone Apr 24, 2019
6cf6357
NULL check on _data assignment
lbernstone Apr 25, 2019
7d9c9be
Changed _data to malloc in order to catch alloc fails
lbernstone Apr 26, 2019
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1 change: 1 addition & 0 deletions libraries/EEPROM/src/EEPROM.cpp
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Expand Up @@ -131,6 +131,7 @@ bool EEPROMClass::begin(size_t size) {
}

_data = new uint8_t[size];
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Where is the NULL check? new does not always succeed.

Chuck.

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@lbernstone does not like NULL checks :D

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Hey, I didn't even write that bit.

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new does not always succeed.

new doesn't always succeed, but it doesn't return NULL unless it's marked with std::nothrow. It throws an exception on failure.

(Arduino is configured with C++ exception handling enabled, but even if exceptions are disabled the firmware will abort() if new fails without being marked std::nothrow)

gcc will even optimize out a null check on a new result if one is added in the code, as it knows the result can't be NULL. (That's ARM, but Xtensa output will be the same for -Os or higher.)

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@projectgus So, it is a stackdump. Why is begin() a boolean function if it can never return a fail? If I used this function, I would assume because of the declaration I am responsible for error checking.

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@projectgus projectgus Apr 26, 2019 •
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I'm not saying you shouldn't check for a failed allocation. I'm saying that a null check on the result of the new operator isn't actually checking anything. There are a number of ways a working out of memory check could be added, the comment hints at some of them.

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(If it was up to me I'd suggest either adding std::nothrow or changing this to malloc().)

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let's go with malloc since that is what is used throughout :)

_size = size;
nvs_get_blob(_handle, _name, _data, &_size);
return true;
}
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