Fixed race conditions for log writing and minor bugs in parser.go

[annab-stripe]

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PR Summary

• Added a mutex to AuditWriter in order to avoid a race condition.

• Added a function rotate to use the mutex to rotate logs.

• Modified tests accordingly to the previous changes and used an atomic.LoadUint32 for n.seq.

• Added the syscall JSON parameter in order for it to appear in AuditMessageGroup.

• Added 1305 to the AddMessage switch in order to not map the uid for that message.

Related Issues

None

Test strategy

Modified the tests in order to work with the mutex changes. Tested in a test environment to verify the 'syscall' parameter was appearing in the JSON struct.

[CLAassistant]

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[nbrownus]

👋 @annab-stripe thanks for the PR. Can you do the CLA bit for us?

[annab-stripe]

Hi, somebody from Stripe legal team signed one for me an year ago.