The copy_file_range does not work inside Circle-CI nested Docker containers spawned using setup_remote_docker.
This demo contains reproducers written in Go and C.
The build jobs in .circleci/config work fine on my local machine but fail on CircleCI.
See failing builds at: https://app.circleci.com/pipelines/github/zrepl/circleci_build_failure_reproducer_copy_file_range/
When running golang:latest (or more precisely golang:1.15 or newer), Go builds and/or invocations of the Linux copy_file_range syscall will fail like so:
go build runtime: copying /usr/local/go/src/runtime/tls_arm64.h to /tmp/go-build523120453/b008/tls_GOARCH.h: write /tmp/go-build523120453/b008/tls_GOARCH.h: copy_file_range: operation not permitted
The reason for these failures is that Go 1.15 starts to use copy_file_range automatically for io.Copy(*os.File, *os.File): golang/go#36817