Add Google Cloud Storage provider

Also convert ETag from GCS-style base64 to AWS-style base16.

README.md

@@ -22,6 +22,7 @@ Supported object stores:
 * azureblob
 * cloudfiles-uk and cloudfiles-us
 * filesystem (on-disk storage)
+* google-cloud-storage
 * hpcloud-objectstorage
 * s3
 * swift and swift-keystone

pom.xml

@@ -204,6 +204,11 @@
       <artifactId>glacier</artifactId>
       <version>${jclouds.version}</version>
     </dependency>
+    <dependency>
+      <groupId>org.apache.jclouds.labs</groupId>
+      <artifactId>google-cloud-storage</artifactId>
+      <version>${jclouds.version}</version>
+    </dependency>
     <dependency>
       <groupId>org.assertj</groupId>
       <artifactId>assertj-core</artifactId>

src/main/java/org/gaul/s3proxy/S3ProxyHandler.java

@@ -552,6 +552,8 @@ final class S3ProxyHandler extends AbstractHandler {
                 }
                 String eTag = metadata.getETag();
                 if (eTag != null) {
+                    String id = blobStore.getContext().unwrap()
+                            .getProviderMetadata().getId();
                     writer.write("    <ETag>&quot;");
                     if (eTag.startsWith("0x")) {
                         // Azure returns Etag as 0x8D1895E13DF8EF1 but S3
@@ -561,6 +563,9 @@ final class S3ProxyHandler extends AbstractHandler {
                             writer.write(Strings.repeat("0", 16 -
                                     eTag.length()));
                         }
+                    } else if (id.equals("google-cloud-storage")) {
+                        eTag = BaseEncoding.base16().lowerCase().encode(
+                                BaseEncoding.base64().decode(eTag));
                     }
                     writer.write(eTag);
                     writer.write("&quot;</ETag>\r\n");