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Commit 63ec4c61 authored by Akilesh Kailash's avatar Akilesh Kailash
Browse files

libsnapshot: Verify the ordering of COW operations. 



Sequence op should contain all ordered ops followed
by Replace and Zero ops. There shouldn't be any non-ordered
ops embedded between ordered ops in the sequence ordering.

Bug: 290159346
Test: inspect_cow <cow_file>, OTA
Change-Id: Ia840340b0e4be07525f216838043bf0265f690c3
Signed-off-by: default avatarAkilesh Kailash <akailash@google.com>
parent 4a33c22c

fs_mgr/libsnapshot/libsnapshot_cow/cow_reader.cpp

+25 −0
Original line number Original line Diff line number Diff line
@@ -310,9 +310,34 @@ bool CowReader::PrepMergeOps() { 
bool CowReader::VerifyMergeOps() {

bool CowReader::VerifyMergeOps() {

    auto itr = GetMergeOpIter(true);

    auto itr = GetMergeOpIter(true);

    std::unordered_map<uint64_t, const CowOperation*> overwritten_blocks;

    std::unordered_map<uint64_t, const CowOperation*> overwritten_blocks;

    bool non_ordered_op_found = false;



    while (!itr->AtEnd()) {

    while (!itr->AtEnd()) {

        const auto& op = itr->Get();

        const auto& op = itr->Get();

        uint64_t offset;

        uint64_t offset;



        // Op should not be a metadata

        if (IsMetadataOp(*op)) {

            LOG(ERROR) << "Metadata op: " << op << " found during merge sequence";

            return false;

        }



        // Sequence ops should contain all the ordered ops followed

        // by Replace and Zero ops. If we find the first op which

        // is not ordered, that means all ordered ops processing

        // has been completed.

        if (!IsOrderedOp(*op)) {

            non_ordered_op_found = true;

        }



        // Since, all ordered ops processing has been completed,

        // check that the subsequent ops are not ordered.

        if (non_ordered_op_found && IsOrderedOp(*op)) {

            LOG(ERROR) << "Invalid sequence - non-ordered and ordered ops"

                       << " cannot be mixed during sequence generation";

            return false;

        }



        if (!GetSourceOffset(op, &offset)) {

        if (!GetSourceOffset(op, &offset)) {

            itr->Next();

            itr->Next();

            continue;

            continue;