expression: handle corrupted length in uncompress builtin function

[ziyi-yan]

What problem does this PR solve?

fixes #8578

What is changed and how it works?

Returns nil with warning when the length in first four bytes is less than the length of the returned string.

While fixing this issue, I change the error class of errZlibZData from ClassTypes to ClassExpression in order to display their SQL error codes correctly.

Check List

Tests

• Unit test
• Integration test

Related changes

• Need to cherry-pick to the release branch
• Need to be included in the release note

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This change is 

[sre-bot]

Hi contributor, thanks for your PR.

This patch needs to be approved by someone of admins. They should reply with "/ok-to-test" to accept this PR for running test automatically.

[ziyi-yan]

PTAL @zimulala

[zimulala]

LGTM

[zimulala]

/run-all-tests

[ziyi-yan]

ping @zimulala @shenli

[zz-jason]

LGTM

[zz-jason]

/run-all-tests

[ziyi-yan]

Are there any problems blocking this PR?

[zz-jason]

@ziyi-yan Could you help us cherry-pick this commit to release-2.1 and release-2.0?

[ziyi-yan]

@zz-jason I would love to do it. But what am I supposed to do exactly? (I am not an experienced contributor yet.)
I might run git cherry-pick <this-commit-id> to branch release-2.0 and release-2.1 and make two PRs to these branches. Is that correct?

[zz-jason]

@zz-jason I would love to do it. But what am I supposed to do exactly? (I am not an experienced contributor yet.)
I might run git cherry-pick <this-commit-id> to branch release-2.0 and release-2.1 and make two PRs to these branches. Is that correct?

Yes, that's right. Feel free to ask if you encountered any problem. 😄