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 428a5897b05074ebcae62029659adbace64314c7..34a6391e9b3ddc6a3342b4e3463003843bf59a23 100644
--- a/mojo/common/data_pipe_utils.cc
+++ b/mojo/common/data_pipe_utils.cc
@@ -58,6 +58,49 @@ size_t CopyToFileHelper(FILE* fp, const void* buffer, uint32_t num_bytes) {
   return fwrite(buffer, 1, num_bytes, fp);
 }
 
+bool BlockingCopyFromFile(const base::FilePath& source,
+                          ScopedDataPipeProducerHandle destination) {
+  base::File file(source, base::File::FLAG_OPEN | base::File::FLAG_READ);
+  if (!file.IsValid())
+    return false;
+  for (;;) {
+    void* buffer;

[Aaron Boodman, 2014/11/03 19:20:15]

= nullptr; I know the code above does not do it. That code is wrong :).

[qsr, 2014/11/04 11:58:34]

Done. But I do not understand why you say this code is wrong. The data is
initialized (through BeginWriteDataRaw) before being used. So, yes the buffer is
not initialized until then, but why would the code be wrong?

[Aaron Boodman, 2014/11/04 18:05:00]

Sorry, I was exaggerating for comedic effect. As if to say that failing to
initializing a local if morally, or ethically wrong.

In truth, it is wrong, at least in the stylistic sense:
http://google-styleguide.googlecode.com/svn/trunk/cppguide.html#Local_Variables

+    uint32_t buffer_num_bytes;

[Aaron Boodman, 2014/11/03 19:20:14]

= 0;

[qsr, 2014/11/04 11:58:33]

Done.

+    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 consumder handle was closed, then treat as EOF.

[Aaron Boodman, 2014/11/03 19:20:14]

typo: consumer

[qsr, 2014/11/04 11:58:34]

Done.

+        return result == MOJO_RESULT_FAILED_PRECONDITION;
+      }
+    } else {
+      // If the consumder handle was closed, then treat as EOF.
+      return result == MOJO_RESULT_FAILED_PRECONDITION;
+    }
+  }
+  NOTREACHED();
+  return false;
+}
+
 } // namespace
 
 
@@ -90,5 +133,16 @@ void CopyToFile(ScopedDataPipeConsumerHandle source,
       callback);
 }
 
+void CopyFromFile(const base::FilePath& source,

[Aaron Boodman, 2014/11/03 19:20:15]

Can you add a unit test for this?

[qsr, 2014/11/04 11:58:34]

Done.

+                  ScopedDataPipeProducerHandle destination,
+                  base::TaskRunner* task_runner,
+                  const base::Callback<void(bool)>& callback) {
+  base::PostTaskAndReplyWithResult(
+      task_runner,
+      FROM_HERE,
+      base::Bind(&BlockingCopyFromFile, source, base::Passed(&destination)),
+      callback);
+}
+
 }  // namespace common
 }  // namespace mojo