From: David Reiss <dreiss@apache.org>
Date: Wed, 29 Oct 2008 22:50:34 +0000 (+0000)
Subject: THRIFT-168. cpp: Clear transport buffers before a flush
X-Git-Tag: 0.2.0~416
X-Git-Url: https://source.supwisdom.com/gerrit/gitweb?a=commitdiff_plain;h=d90cd1f539f5837858aa64256d187b4444560b81;p=common%2Fthrift.git

THRIFT-168. cpp: Clear transport buffers before a flush

Previously, TBufferedTransport and TFramedTransport could
leave data in their buffers if a flush threw an exception.
This patch makes them reset their internal pointers before
flushing to the underlying transport.


git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@709037 13f79535-47bb-0310-9956-ffa450edef68
---

diff --git a/lib/cpp/src/transport/TBufferTransports.cpp b/lib/cpp/src/transport/TBufferTransports.cpp
index b26fd3d3..15830149 100644
--- a/lib/cpp/src/transport/TBufferTransports.cpp
+++ b/lib/cpp/src/transport/TBufferTransports.cpp
@@ -135,8 +135,11 @@ void TBufferedTransport::flush()  {
   // Write out any data waiting in the write buffer.
   uint32_t have_bytes = wBase_ - wBuf_.get();
   if (have_bytes > 0) {
-    transport_->write(wBuf_.get(), have_bytes);
+    // Note that we reset wBase_ prior to the underlying write
+    // to ensure we're in a sane state (i.e. internal buffer cleaned)
+    // if the underlying write throws up an exception
     wBase_ = wBuf_.get();
+    transport_->write(wBuf_.get(), have_bytes);
   }
 
   // Flush the underlying transport.
@@ -231,17 +234,16 @@ void TFramedTransport::flush()  {
   memcpy(wBuf_.get(), (uint8_t*)&sz_nbo, sizeof(sz_nbo));
 
   if (sz_hbo > 0) {
+    // Note that we reset wBase_ (with a pad for the frame size)
+    // prior to the underlying write to ensure we're in a sane state
+    // (i.e. internal buffer cleaned) if the underlying write throws
+    // up an exception
+    wBase_ = wBuf_.get() + sizeof(sz_nbo);
+
     // Write size and frame body.
     transport_->write(wBuf_.get(), sizeof(sz_nbo)+sz_hbo);
   }
 
-  // Reset our pointers.
-  wBase_ = wBuf_.get();
-
-  // Pad the buffer so we can insert the size later.
-  uint32_t pad = 0;
-  this->write((uint8_t*)&pad, sizeof(pad));
-
   // Flush the underlying transport.
   transport_->flush();
 }