convert: don't drop commits that are empty in the source when using --filemap
I ran into this when using `hg lfconvert --to-normal` (which uses the filemap
class internally), and saw that commits with nothing but a branch change were
dropped. We could put in an option that only lfconvert uses internally. But
silently dropping anything other than a commit where all changes were excluded
seems unintended. For example, there's a message in mercurial_sink.putcommit()
if it drops an empty commit. (And the reason that isn't kicking in here is
because lfconvert isn't passing --filemap, so the self.filemapmode conditional
there is always False.)
The naive change of `return not files` broke test-convert-filemap.t, so this is
a little more elaborate than needed for converting from largefiles.
#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;
}