nacl_io patch for blob URLs

--- a/nacl_sdk/pepper_canary/src/nacl_io/httpfs/http_fs.cc
+++ b/nacl_sdk/pepper_canary/src/nacl_io/httpfs/http_fs.cc
@@ -213,9 +213,11 @@ Error HttpFs::Init(const FsInitArgs& args) {
        ++iter) {
     if (iter->first == "SOURCE") {
       url_root_ = iter->second;
+      is_blob_url_ = url_root_.substr(0,5) == "blob:";

       // Make sure url_root_ ends with a slash.
-      if (!url_root_.empty() && url_root_[url_root_.length() - 1] != '/') {
+      // Blob URLs must not get a slash appended.
+      if (!url_root_.empty() && !is_blob_url_ && url_root_[url_root_.length() - 1] != '/') {
         url_root_ += '/';
       }
     } else if (iter->first == "manifest") {


--- a/nacl_sdk/pepper_canary/src/nacl_io/httpfs/http_fs_node.cc
+++ b/nacl_sdk/pepper_canary/src/nacl_io/httpfs/http_fs_node.cc
@@ -234,18 +236,36 @@ Error HttpFsNode::GetStat_Locked(struct stat* stat) {
     ScopedResource response(filesystem_->ppapi());
     int32_t statuscode;
     StringMap_t response_headers;
-    Error error = OpenUrl("HEAD",
-                          &headers,
-                          &loader,
-                          &request,
-                          &response,
-                          &statuscode,
-                          &response_headers);
+    Error error(0);
+
+    // TODO: data URLs
+    if (filesystem->is_blob_url_) {
+      // Blob URLs do not support HEAD requests, but do give the content length
+      // in their response headers. We issue a single-byte GET request to retrieve
+      // the content length.
+      headers["Range"] = "bytes=0-0";
+      error = OpenUrl("GET",
+                      &headers,
+                      &loader,
+                      &request,
+                      &response,
+                      &statuscode,
+                      &response_headers);
+    } else {
+      error = OpenUrl("HEAD",
+                      &headers,
+                      &loader,
+                      &request,
+                      &response,
+                      &statuscode,
+                      &response_headers);
+    }
+
     if (error)
       return error;

-    size_t entity_length;
-    if (ParseContentLength(response_headers, &entity_length)) {
+    size_t read_start, read_end, entity_length;
+    if ((filesystem->is_blob_url_ && ParseContentRange(response_headers, &read_start, &read_end, &entity_length)) || (!filesystem->is_blob_url_ && ParseContentLength(response_headers, &entity_length))) {
       SetCachedSize(static_cast<off_t>(entity_length));
     } else if (cache_content_) {
       // The server didn't give a content length; download the data to memory



--- a/nacl_sdk/pepper_canary/include/nacl_io/httpfs/http_fs.h
+++ b/nacl_sdk/pepper_canary/include/nacl_io/httpfs/http_fs.h
@@ -53,6 +53,7 @@ class HttpFs : public Filesystem {
   bool allow_credentials_;
   bool cache_stat_;
   bool cache_content_;
+  bool is_blob_url_;

   friend class TypedFsFactory<HttpFs>;
   friend class HttpFsNode;