view contrib/fuzz/fuzzutil.cc @ 42229:5a3979529740

copies: clarify mutually exclusive cases in _chain() with a s/if/elif/

If the 'b' dict has a rename from 'x' to 'y', it shouldn't be possible
for 'x' to be both (a key) in 'a' and in 'src'. That would mean that
'x' is a file in the source commit and also a rename destination in
the intermediate commit. But we currently don't allow renaming files
onto existing files, so that shouldn't happen. So let's clarify that
by using an "elif" instead of an "if". And if we did allow renaming
files onto existing files, we should prefer to use the rename
destination in the intermediate commit as source anyway.

Differential Revision: https://phab.mercurial-scm.org/D6276

#include "fuzzutil.h"

#include <cstring>
#include <utility>

contrib::optional<two_inputs> SplitInputs(const uint8_t *Data, size_t Size)
{
	if (!Size) {
		return contrib::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]);
	std::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]);
	std::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;
}