Adds a new method ReadUntilComplete to FileStream which ensure that a...

net/base/file_stream_posix.cc

Index: net/base/file_stream_posix.cc
===================================================================
--- net/base/file_stream_posix.cc	(revision 9711)
+++ net/base/file_stream_posix.cc	(working copy)
@@ -154,6 +154,27 @@
   }
 }
 
+int FileStream::ReadUntilComplete(char *buf, int buf_len) {
+  int to_read = buf_len;
+  int bytes_total = 0;
+
+  do {
+    int bytes_read = Read(buf, to_read, NULL);
+    if (bytes_read <= 0) {
+      if (bytes_total == 0)
+        return bytes_read;
+
+      return bytes_total;
+    }
+
+    bytes_total += bytes_read;
+    buf += bytes_read;
+    to_read -= bytes_read;
+  } while (bytes_total < buf_len);
+
+  return bytes_total;
+}
+
 // TODO(deanm): async.
 int FileStream::Write(
     const char* buf, int buf_len, CompletionCallback* callback) {