api: refactor the bucket policy reading and writing. (#2395)

Policies are read once during server startup and subsequently
managed through in memory map. In-memory map is updated as
and when there are new changes coming in.

bucket-policy.go

@@ -18,25 +18,111 @@ package main
 
 import (
 	"bytes"
-	"path/filepath"
+	"errors"
+	"io"
+	"path"
+	"sync"
 )
 
-// getBucketsConfigPath - get buckets path.
+// Variable represents bucket policies in memory.
+var globalBucketPolicies *bucketPolicies
+
+// Global bucket policies list, policies are enforced on each bucket looking
+// through the policies here.
+type bucketPolicies struct {
+	rwMutex *sync.RWMutex
+
+	// Collection of 'bucket' policies.
+	bucketPolicyConfigs map[string]*bucketPolicy
+}
+
+// Fetch bucket policy for a given bucket.
+func (bp bucketPolicies) GetBucketPolicy(bucket string) *bucketPolicy {
+	bp.rwMutex.RLock()
+	defer bp.rwMutex.RUnlock()
+	return bp.bucketPolicyConfigs[bucket]
+}
+
+// Set a new bucket policy for a bucket, this operation will overwrite
+// any previous bucketpolicies for the bucket.
+func (bp *bucketPolicies) SetBucketPolicy(bucket string, policy *bucketPolicy) error {
+	bp.rwMutex.Lock()
+	defer bp.rwMutex.Unlock()
+	if policy == nil {
+		return errors.New("invalid argument")
+	}
+	bp.bucketPolicyConfigs[bucket] = policy
+	return nil
+}
+
+// Remove bucket policy for a bucket, from in-memory map.
+func (bp *bucketPolicies) RemoveBucketPolicy(bucket string) {
+	bp.rwMutex.Lock()
+	defer bp.rwMutex.Unlock()
+	delete(bp.bucketPolicyConfigs, bucket)
+}
+
+// Loads all bucket policies from persistent layer.
+func loadAllBucketPolicies(objAPI ObjectLayer) (policies map[string]*bucketPolicy, err error) {
+	// List buckets to proceed loading all notification configuration.
+	buckets, err := objAPI.ListBuckets()
+	if err != nil {
+		return nil, err
+	}
+	policies = make(map[string]*bucketPolicy)
+	// Loads bucket policy.
+	for _, bucket := range buckets {
+		var policy *bucketPolicy
+		policy, err = readBucketPolicy(bucket.Name, objAPI)
+		if err != nil {
+			switch err.(type) {
+			case BucketPolicyNotFound:
+				continue
+			}
+			return nil, err
+		}
+		policies[bucket.Name] = policy
+	}
+
+	// Success.
+	return policies, nil
+
+}
+
+// Intialize all bucket policies.
+func initBucketPolicies(objAPI ObjectLayer) error {
+	if objAPI == nil {
+		return errInvalidArgument
+	}
+	// Read all bucket policies.
+	policies, err := loadAllBucketPolicies(objAPI)
+	if err != nil {
+		return err
+	}
+
+	globalBucketPolicies = &bucketPolicies{
+		rwMutex:             &sync.RWMutex{},
+		bucketPolicyConfigs: policies,
+	}
+	return nil
+}
+
+// getOldBucketsConfigPath - get old buckets config path. (Only used for migrating old bucket policies)
 func getOldBucketsConfigPath() (string, error) {
 	configPath, err := getConfigPath()
 	if err != nil {
 		return "", err
 	}
-	return filepath.Join(configPath, "buckets"), nil
+	return path.Join(configPath, "buckets"), nil
 }
 
-// readBucketPolicy - read bucket policy.
-func readBucketPolicy(bucket string, objAPI ObjectLayer) ([]byte, error) {
+// readBucketPolicy - reads bucket policy for an input bucket, returns BucketPolicyNotFound
+// if bucket policy is not found. This function also parses the bucket policy into an object.
+func readBucketPolicy(bucket string, objAPI ObjectLayer) (*bucketPolicy, error) {
 	// Verify bucket is valid.
 	if !IsValidBucketName(bucket) {
 		return nil, BucketNameInvalid{Bucket: bucket}
 	}
-
 	policyPath := pathJoin(bucketConfigPrefix, bucket, policyJSON)
 	objInfo, err := objAPI.GetObjectInfo(minioMetaBucket, policyPath)
 	if err != nil {
@@ -53,10 +139,18 @@ func readBucketPolicy(bucket string, objAPI ObjectLayer) ([]byte, error) {
 		}
 		return nil, err
 	}
-	return buffer.Bytes(), nil
+	// Parse the saved policy.
+	var policy = &bucketPolicy{}
+	err = parseBucketPolicy(&buffer, policy)
+	if err != nil {
+		return nil, err
+
+	}
+	return policy, nil
 }
 
-// removeBucketPolicy - remove bucket policy.
+// removeBucketPolicy - removes any previously written bucket policy. Returns BucketPolicyNotFound
+// if no policies are found.
 func removeBucketPolicy(bucket string, objAPI ObjectLayer) error {
 	// Verify bucket is valid.
 	if !IsValidBucketName(bucket) {
@@ -73,14 +167,14 @@ func removeBucketPolicy(bucket string, objAPI ObjectLayer) error {
 	return nil
 }
 
-// writeBucketPolicy - save bucket policy.
-func writeBucketPolicy(bucket string, objAPI ObjectLayer, accessPolicyBytes []byte) error {
+// writeBucketPolicy - save all bucket policies.
+func writeBucketPolicy(bucket string, objAPI ObjectLayer, reader io.Reader, size int64) error {
 	// Verify if bucket path legal
 	if !IsValidBucketName(bucket) {
 		return BucketNameInvalid{Bucket: bucket}
 	}
 
 	policyPath := pathJoin(bucketConfigPrefix, bucket, policyJSON)
-	_, err := objAPI.PutObject(minioMetaBucket, policyPath, int64(len(accessPolicyBytes)), bytes.NewReader(accessPolicyBytes), nil)
+	_, err := objAPI.PutObject(minioMetaBucket, policyPath, size, reader, nil)
 	return err
 }