fix(cp): return non-nil Content from dry-run CopyFromContainer - #13982
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glours wants to merge 1 commit into
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fix(cp): return non-nil Content from dry-run CopyFromContainer#13982glours wants to merge 1 commit into
glours wants to merge 1 commit into
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The caller in pkg/compose/cp.go unconditionally defers res.Content.Close() once the call succeeds. The dry-run client returned a zero-value result with a nil Content reader, so `docker compose cp --dry-run <ctr>:<path> <dst>` panicked with a nil pointer dereference. Return an empty NopCloser instead, matching the pattern already used for the other stream results in this file. Signed-off-by: Guillaume Lours <glours@users.noreply.github.com>
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Assessment: 🟡 NEEDS ATTENTION
One medium-severity confirmed finding: the PR correctly fixes the nil-pointer panic by returning a non-nil Content, but the Stat field in the returned CopyFromContainerResult remains zero-valued. Since ContainerStatPath is already called (and its result discarded), the fix is straightforward: capture and return the Stat so the caller's res.Stat.Mode.IsDir() check works correctly for directory sources in dry-run mode.
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maxproske
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Jul 30, 2026
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Non-binding LGTM
cat > compose.yaml <<'EOF'
services:
app:
image: alpine
EOF
./bin/build/docker-compose create
./bin/build/docker-compose cp --dry-run app:/ .
# no-op instead of panic :)
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What I did
The caller in
pkg/compose/cp.gounconditionally defersres.Content.Close()once the call succeeds. The dry-run client returned a zero-value result with a nilContentreader, sodocker compose cp --dry-run <ctr>:<path> <dst>panicked with a nil pointer dereference. Return an emptyNopCloserinstead, matching the pattern already used for the other stream results in this file.Related issue
https://docker.atlassian.net/browse/DDB-589
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