oci: tar extract: full opaque whiteout support #229
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We can handle generating opaque whiteouts in the future (because we technically shouldn't be generating them). |
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The OCI specification makes it clear that we MUST NOT allow users to have a rootfs that contains '.wh.'-prefixed files. While we cannot prevent them from creating such a rootfs, we can abort when we see it. Also add a test to ensure that this doesn't regress. In addition we error out if we see opaque whiteouts. This is a temporary patch in this series, and will be replaced with full opaque whiteout support in a future commit. Signed-off-by: Aleksa Sarai <[email protected]>
The previous clobbering code was overly complicated and duplicated. While this is technically a no-op change, it makes it clearer what the clobbering semantics actually are (everything gets clobbered except previously-directories that will remain a directory after the extraction). Signed-off-by: Aleksa Sarai <[email protected]>
Rather than looping over Readdirnames, just get them all in the first place. The Go stdlib appears to use both the "get all" and "get some" interfaces of Readdirnames for similar operations (RemoveAll and Walk respectively). It doesn't make sense to use different operations, as they also make the implementation seem more complicated than necessary. Also refactor out the Readdirnames code so that it can be used by Walk in a future patch. Signed-off-by: Aleksa Sarai <[email protected]>
This adds a filepath.Walk implementation to unpriv, that works unprivileged. At the moment the WalkFunc is Wrap'd internally, though this results in the function being called more than once if there's a permission error. This might not be ideal for all users, but it is more transparent I guess? Also add Walk to the fseval interfaces so we can use Walk in oci/layer for the purposes of handling opaque whiteouts. Signed-off-by: Aleksa Sarai <[email protected]>
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Add full opaque whiteout support, including the handling of new files present in the upper layer (and thus should not be removed). The code implementing this is fairly fragile and has to deal with a lot of really annoying edge cases, so many new tests were added for this portion. There are a few semantics differences found between unpriv.Walk and filepath.Walk by this patch (especially when it comes to handling ENOENT during the walk). These semantics have been fixed in the WalkFunc used, but probably deserve a refactor in future. Signed-off-by: Aleksa Sarai <[email protected]>
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LGTM. |
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Add full opaque whiteout support, including the handling of new files
present in the upper layer (and thus should not be removed). The code
implementing this is fairly fragile and has to deal with a lot of really
annoying edge cases, so many new tests were added for this portion.
There are a few semantics differences found between unpriv.Walk and
filepath.Walk by this patch (especially when it comes to handling ENOENT
during the walk). These semantics have been fixed in the WalkFunc used,
but probably deserve a refactor in future.
Closes #224
Signed-off-by: Aleksa Sarai [email protected]