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Copy container.Spec when reading.

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In `execution.Create()` I was seeing `opts.Spec` unexpectedly becoming a slice
full of nulls instead of the expected data (often this occurred at the
`s.mu.Lock()`)

https://github.com/boltdb/bolt#caveats--limitations says:

> Byte slices returned from Bolt are only valid during a transaction. Once the
> transaction has been committed or rolled back then the memory they point to
> can be reused by a new page or can be unmapped from virtual memory and you'll
> see an unexpected fault address panic when accessing it.

Since `opts.Spec` = `container.Spec` where the latter is a byte slice returned
from Bolt we must copy it. The best place to do this is when reading, so that
callers need not worry about this.

I also checked metadata/*.go for similar issues and found no others.

Signed-off-by: Ian Campbell <ian.campbell@docker.com>
This commit is contained in:
Ian Campbell 2017-06-06 11:03:50 +01:00
parent 4ae34cccc5
commit 961e12b736
1 changed files with 2 additions and 1 deletions
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3
metadata/containers.go
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@ -120,7 +120,8 @@ func readContainer(container *containers.Container, bkt *bolt.Bucket) error {
case string(bucketKeyRuntime): case string(bucketKeyRuntime):
container.Runtime = string(v) container.Runtime = string(v)
case string(bucketKeySpec): case string(bucketKeySpec):
container.Spec = v container.Spec = make([]byte, len(v))
copy(container.Spec, v)
case string(bucketKeyRootFS): case string(bucketKeyRootFS):
container.RootFS = string(v) container.RootFS = string(v)
case string(bucketKeyLabels): case string(bucketKeyLabels):