Add share functionality for S3

Signed-off-by: Knut Ahlers <knut@ahlers.me>

providers/s3/provider.go

@@ -2,7 +2,9 @@ package s3
 
 import (
 	"bytes"
+	"context"
 	"crypto/md5"
+	"fmt"
 	"hash"
 	"io"
 	"net/url"
@@ -12,14 +14,16 @@ import (
 	"github.com/aws/aws-sdk-go/aws/credentials"
 	"github.com/aws/aws-sdk-go/aws/session"
 	"github.com/aws/aws-sdk-go/service/s3"
+	"github.com/aws/aws-sdk-go/service/s3/s3manager"
 	"github.com/pkg/errors"
 
 	"github.com/Luzifer/cloudbox/providers"
 )
 
 type Provider struct {
-	bucket string
-	s3     *s3.S3
+	bucket       string
+	bucketRegion string
+	s3           *s3.S3
 }
 
 func New(uri string) (providers.CloudProvider, error) {
@@ -39,11 +43,18 @@ func New(uri string) (providers.CloudProvider, error) {
 		cfg = cfg.WithCredentials(credentials.NewStaticCredentials(user, pass, ""))
 	}
 
-	svc := s3.New(session.Must(session.NewSession(cfg)))
+	sess := session.Must(session.NewSession(cfg))
+	svc := s3.New(sess)
+
+	region, err := s3manager.GetBucketRegion(context.Background(), sess, u.Host, "us-east-1")
+	if err != nil {
+		return nil, errors.Wrap(err, "Unable to find bucket region")
+	}
 
 	return &Provider{
-		bucket: u.Host,
-		s3:     svc,
+		bucket:       u.Host,
+		bucketRegion: region,
+		s3:           svc,
 	}, nil
 }
 
@@ -119,6 +130,7 @@ func (p *Provider) PutFile(f providers.File) (providers.File, error) {
 	}
 
 	if _, err = p.s3.PutObject(&s3.PutObjectInput{
+		ACL:    aws.String(p.getFileACL(f.Info().RelativeName)),
 		Body:   bytes.NewReader(buf.Bytes()),
 		Bucket: aws.String(p.bucket),
 		Key:    aws.String(f.Info().RelativeName),
@@ -130,5 +142,33 @@ func (p *Provider) PutFile(f providers.File) (providers.File, error) {
 }
 
 func (p *Provider) Share(relativeName string) (string, error) {
-	return "", errors.New("Not implemented")
+	_, err := p.s3.PutObjectAcl(&s3.PutObjectAclInput{
+		ACL:    aws.String(s3.ObjectCannedACLPublicRead),
+		Bucket: aws.String(p.bucket),
+		Key:    aws.String(relativeName),
+	})
+	if err != nil {
+		return "", errors.Wrap(err, "Unable to publish file")
+	}
+
+	return fmt.Sprintf("https://s3-%s.amazonaws.com/%s/%s", p.bucketRegion, p.bucket, relativeName), nil
+}
+
+func (p *Provider) getFileACL(relativeName string) string {
+	objACL, err := p.s3.GetObjectAcl(&s3.GetObjectAclInput{
+		Bucket: aws.String(p.bucket),
+		Key:    aws.String(relativeName),
+	})
+
+	if err != nil {
+		return s3.ObjectCannedACLPrivate
+	}
+
+	for _, g := range objACL.Grants {
+		if *g.Grantee.URI == "http://acs.amazonaws.com/groups/global/AllUsers" && *g.Permission == "READ" {
+			return s3.ObjectCannedACLPublicRead
+		}
+	}
+
+	return s3.ObjectCannedACLPrivate
 }