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Not embedding hclConfig as a pointer. #1710
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This addresses the panic within #1704. The problem here is that, if you embed a pointer to a private struct, and the private struct is nil, the caller has no way to determine if the embedded struct's values are safe to access. This manifests here: https://github.com/hashicorp/waypoint/blob/main/internal/cli/base.go#L253 There is no way to determine of c.cfg.Runner is safe to access. A simplified example of the problem: https://play.golang.org/p/sbAPT2HGJqW I believe so - we don't have any methods on hclConfig that require it to be a pointer. We also never statefully maniuplate it outside of the context of `cfg`, as far as I can see. I've tested this locally and it doesn't seem to break anything.
evanphx
approved these changes
Jun 30, 2021
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Because the expectation is that users outside this package are going to be accessing things like Runner on Config, but via hclConfig, it makes sense to have hclConfig be a value and not a pointer because those outside users can't even nil check hclConfig. Ergo it makes sense to just have hclConfig be a value.
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What problem is this solving?
This addresses the panic within #1704.
The problem here is that, if we embed a pointer to a private struct, and the private struct is nil, the caller has no way to determine if the embedded struct's values are safe to access.
This manifests here:
waypoint/internal/cli/base.go
Line 253 in 124f455
There is no way to determine of
c.cfg.Runneris safe to access.c.cfgcan be non-nil on its own, but it will become nil when inspectingc.cfg.Runnerif the embedded*hclConfigis nil.A simplified example of the problem:
https://play.golang.org/p/sbAPT2HGJqW
If hclConfig is not a pointer, we won't get a nil pointer deference when looking at its fields.
Is this change safe?
I believe so - we don't have any methods on hclConfig that require it to be a pointer. We also never statefully maniuplate it outside of the context of
cfg, as far as I can see. I've tested this locally and it doesn't seem to break anything.