* evaluate policies during authorization
* cache bucket policy
* refactor
* matching with regex special characters
* Case Sensitivity, pattern cache, Dead Code Removal
* Fixed Typo, Restored []string Case, Added Cache Size Limit
* hook up with policy engine
* remove old implementation
* action mapping
* validate
* if not specified, fall through to IAM checks
* fmt
* Fail-close on policy evaluation errors
* Explicit `Allow` bypasses IAM checks
* fix error message
* arn:seaweed => arn:aws
* remove legacy support
* fix tests
* Clean up bucket policy after this test
* fix for tests
* address comments
* security fixes
* fix tests
* temp comment out
see https://blog.aqwari.net/xml-schema-go/
1. go get aqwari.net/xml/cmd/xsdgen
2. Add EncodingType element for ListBucketResult in AmazonS3.xsd
3. xsdgen -o s3api_xsd_generated.go -pkg s3api AmazonS3.xsd
4. Remove empty Grantee struct in s3api_xsd_generated.go
5. Remove xmlns: sed s'/http:\/\/s3.amazonaws.com\/doc\/2006-03-01\/\ //' s3api_xsd_generated.go
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