Mercurial > public > mercurial-scm > hg
diff contrib/fuzz/fuzzutil.cc @ 38173:fa0ddd5e8fff
fuzz: extract some common utilities and use modern C++ idioms
Alex Gaynor suggested we should probably copy the left and right sides
of diffs to new blocks so we can detect over-reads in the diffing
code, and I agree. Once I got into that, I realized we should do
things with C++17 idioms rather than keep using malloc() and
free(). This change is the result. I tried to split it more than this
and failed.
Everything still compiles and works in the oss-fuzz container, so I
think we can count on C++17 being available!
Differential Revision: https://phab.mercurial-scm.org/D3675
| author | Augie Fackler <augie@google.com> |
|---|---|
| date | Sat, 28 Apr 2018 22:18:50 -0400 |
| parents | |
| children | 36d55f90e2a3 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/contrib/fuzz/fuzzutil.cc Sat Apr 28 22:18:50 2018 -0400 @@ -0,0 +1,26 @@ +#include "fuzzutil.h" + +#include <utility> + +std::optional<two_inputs> SplitInputs(const uint8_t *Data, size_t Size) +{ + if (!Size) { + return std::nullopt; + } + // figure out a random point in [0, Size] to split our input. + size_t left_size = (Data[0] / 255.0) * (Size - 1); + + // Copy inputs to new allocations so if bdiff over-reads + // AddressSanitizer can detect it. + std::unique_ptr<char[]> left(new char[left_size]); + memcpy(left.get(), Data + 1, left_size); + // right starts at the next byte after left ends + size_t right_size = Size - (left_size + 1); + std::unique_ptr<char[]> right(new char[right_size]); + memcpy(right.get(), Data + 1 + left_size, right_size); + LOG(2) << "inputs are " << left_size << " and " << right_size + << " bytes" << std::endl; + two_inputs result = {std::move(right), right_size, std::move(left), + left_size}; + return result; +}