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Harden merging of VLAs #15368

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Harden merging of VLAs #15368

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18 changes: 17 additions & 1 deletion Framework/AODMerger/src/aodMerger.cxx
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Original file line number Diff line number Diff line change
Expand Up @@ -286,6 +286,21 @@ int main(int argc, char* argv[])
}
outputDir->cd();
auto outputTree = inputTree->CloneTree(-1, (fastCopy) ? "fast" : "");
// Validate that all branches have the same number of entries after CloneTree.
// Fast copy from remote (xrootd) sources can silently produce corrupt trees
// if a read fails mid-transfer.
{
auto expectedEntries = outputTree->GetEntries();
TObjArray* clonedBranches = outputTree->GetListOfBranches();
for (int ib = 0; ib < clonedBranches->GetEntriesFast(); ++ib) {
auto* br = (TBranch*)clonedBranches->UncheckedAt(ib);
if (br->GetEntries() != expectedEntries) {
printf(" *** FATAL ***: After CloneTree, branch %s has %lld entries but tree has %lld\n",
br->GetName(), br->GetEntries(), expectedEntries);
exitCode = 7;
}
}
}
currentDirSize += inputTree->GetTotBytes(); // NOTE outputTree->GetTotBytes() is 0, so we use the inputTree here
alreadyCopied = true;
outputTree->SetAutoFlush(0);
Expand All @@ -308,6 +323,7 @@ int main(int argc, char* argv[])
// detect VLA
if (((TLeaf*)br->GetListOfLeaves()->First())->GetLeafCount() != nullptr) {
int maximum = ((TLeaf*)br->GetListOfLeaves()->First())->GetLeafCount()->GetMaximum();
maximum = std::max(maximum, 1);
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@jgrosseo jgrosseo May 6, 2026

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Suggested change
maximum = std::max(maximum, 1);
maximum = std::max(maximum, 1); // Can be 0 if all VLAs are empty but we need a valid buffer below


// get type
static TClass* cls;
Expand Down Expand Up @@ -477,4 +493,4 @@ int main(int argc, char* argv[])
printf("\n");

return exitCode;
}
}