handle allocations for problematic structs to avoid sharing pointers-to-pointers with C (from Go) #82
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This reverts commit 841ff78.
…ter issues with CGO
Kubuxu
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May 5, 2020
gracenoah
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Dec 20, 2020
…to-pointers with C (from Go) (filecoin-project#82) * alternative verify post * manually allocate proxy object to prevent sharing Go heap with C * Revert "alternative verify post" This reverts commit 841ff78. * manually allocate proxy object to prevent sharing Go heap with C * pass flattened messages to fil_hash_verify to prevent pointer-to-pointer issues with CGO * rename symbols within custom allocate methods * run go test with cgocheck=2 * delete temporary branches from circleci config
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For additional background, read this thread.
Why does this PR exist?
When running software that consumed filecoin-ffi, setting
GODEBUG=cgocheck=2option produced the following error:The cause of this error is that c-for-go generated code which mapped a slice of Go structs to a dynamic array of their C equivalents, but when those Go structs had fields which were
stringor[]byte, a pointer to the original Go slice would be shared with C (instead of copying the nested value into the C heap). I suspect that this was by-design.What's in this PR?
To appease the gods, I have written custom allocating methods for the two structs which cause the reported issue. I have also rewritten the
fil_verify_hashfunction to accept a flattened byte array, which prevents the double-pointer error.