Fix Undefined Behavior by replacing illegal overlap test with memmove() #924
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…gs_overlap" This reverts commit 078c4e6.
This reverts commit 4f4d7f7.
This reverts commit b47edc4.
According to the C standard it is Undefined Behavior to arithmetically compare addresses that don't point to within the same object. There is simply no way to implement this sort of check legally. The correct way to avoid problems from overlapping strings is to replace strcpy() with memmove().
Minor optimizations to cJSON_SetValueString() program flow: - NULL check the input first before going into more detail. - Check the type flags with one bitwise AND instead of two. - Remove a redundant second object->valuestring NULL check.
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@DaveGamble are you busy with life these days? It's understandable. But it would be nice to see cJSON improve, too. |
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I pointed this out in #919, sorry for taking so long to make a PR. But here it is. No need to check for string overlap–it's simply not legal in C, and
memmove()exists to guarantee that overlapping copies don't cause unforeseen problems.