Allow local file to run though content handler.

mojo/common/data_pipe_utils.cc

Index: mojo/common/data_pipe_utils.cc
diff --git a/mojo/common/data_pipe_utils.cc b/mojo/common/data_pipe_utils.cc
index b26b1946cf7ed53a8c77012152cd939d4e37f1a9..c24ea53d4696aca0c4036b593654cf36cbcc10a5 100644
--- a/mojo/common/data_pipe_utils.cc
+++ b/mojo/common/data_pipe_utils.cc
@@ -20,8 +20,8 @@ namespace {
 bool BlockingCopyHelper(ScopedDataPipeConsumerHandle source,
     const base::Callback<size_t(const void*, uint32_t)>& write_bytes) {
   for (;;) {
-    const void* buffer;
-    uint32_t num_bytes;
+    const void* buffer = nullptr;
+    uint32_t num_bytes = 0;
     MojoResult result = BeginReadDataRaw(
         source.get(), &buffer, &num_bytes, MOJO_READ_DATA_FLAG_NONE);
     if (result == MOJO_RESULT_OK) {
@@ -173,6 +173,53 @@ PeekStatus PeekNBytes(size_t bytes_length,
   return PeekStatus::kKeepReading;
 }
 
+bool BlockingCopyFromFile(const base::FilePath& source,
+                          ScopedDataPipeProducerHandle destination,
+                          uint32_t skip) {
+  base::File file(source, base::File::FLAG_OPEN | base::File::FLAG_READ);
+  if (!file.IsValid())
+    return false;
+  if (file.Seek(base::File::FROM_BEGIN, skip) != skip) {
+    return false;
+  }
+  for (;;) {
+    void* buffer;
+    uint32_t buffer_num_bytes;
+    MojoResult result = BeginWriteDataRaw(destination.get(),
+                                          &buffer,
+                                          &buffer_num_bytes,
+                                          MOJO_WRITE_DATA_FLAG_NONE);
+    if (result == MOJO_RESULT_OK) {
+      int bytes_read =
+          file.ReadAtCurrentPos(static_cast<char*>(buffer), buffer_num_bytes);
+      if (bytes_read >= 0) {
+        EndWriteDataRaw(destination.get(), bytes_read);
+        if (bytes_read == 0) {
+          // eof
+          return true;
+        }
+      } else {
+        // error
+        EndWriteDataRaw(destination.get(), 0);
+        return false;
+      }
+    } else if (result == MOJO_RESULT_SHOULD_WAIT) {
+      result = Wait(destination.get(),
+                    MOJO_HANDLE_SIGNAL_WRITABLE,
+                    MOJO_DEADLINE_INDEFINITE);
+      if (result != MOJO_RESULT_OK) {
+        // If the consumer handle was closed, then treat as EOF.
+        return result == MOJO_RESULT_FAILED_PRECONDITION;
+      }
+    } else {
+      // If the consumer handle was closed, then treat as EOF.
+      return result == MOJO_RESULT_FAILED_PRECONDITION;
+    }
+  }
+  NOTREACHED();
+  return false;
+}
+
 } // namespace
 
 bool BlockingPeekNBytes(DataPipeConsumerHandle source,
@@ -220,5 +267,18 @@ void CopyToFile(ScopedDataPipeConsumerHandle source,
       callback);
 }
 
+void CopyFromFile(const base::FilePath& source,
+                  ScopedDataPipeProducerHandle destination,
+                  uint32_t skip,
+                  base::TaskRunner* task_runner,
+                  const base::Callback<void(bool)>& callback) {
+  base::PostTaskAndReplyWithResult(
+      task_runner,
+      FROM_HERE,
+      base::Bind(
+          &BlockingCopyFromFile, source, base::Passed(&destination), skip),
+      callback);
+}
+
 }  // namespace common
 }  // namespace mojo