From 9980a0bfcb36b485c540a0fa372081eb610aa17d Mon Sep 17 00:00:00 2001
From: Charles Galambos <craftit@gmail.com>
Date: Tue, 19 May 2015 11:51:48 +0100
Subject: [PATCH] CXX-603 Fix for dropping parts of blocks appended to a gridfs
 file with appendChunk

and add unit test for gridfs GridFileBuilder to check it handles block boundries correctly

Signed-off-by: Andrew Morrow <acm@mongodb.com>
---
 src/mongo/client/gridfs.cpp                   |  9 +++++-
 .../integration/standalone/gridfs_test.cpp    | 32 ++++++++++++++++---
 2 files changed, 36 insertions(+), 5 deletions(-)

diff --git a/src/mongo/client/gridfs.cpp b/src/mongo/client/gridfs.cpp
index fd53fcb209..d57d73cbfa 100644
--- a/src/mongo/client/gridfs.cpp
+++ b/src/mongo/client/gridfs.cpp
@@ -321,7 +321,14 @@ namespace mongo {
             invariant( _pendingDataSize <= _chunkSize );
             if (_pendingDataSize == _chunkSize) {
                 _appendPendingData();
-                _appendChunk( data + size, length - size, false );
+                const char* const end = data + length;
+                data = _appendChunk( data + size, length - size, false );
+                if (data != end) {
+                    invariant(data < end);
+                    size_t nsize = static_cast<size_t>(end - data);
+                    memcpy( _pendingData.get() + _pendingDataSize, data, nsize );
+                    _pendingDataSize += nsize;
+                }
             }
         }
         else {
diff --git a/src/mongo/integration/standalone/gridfs_test.cpp b/src/mongo/integration/standalone/gridfs_test.cpp
index b4f7c3bbdc..15a1b15067 100644
--- a/src/mongo/integration/standalone/gridfs_test.cpp
+++ b/src/mongo/integration/standalone/gridfs_test.cpp
@@ -226,21 +226,45 @@ namespace {
 
     TEST_F(GridFSTest, GridFileBuilder) {
         GridFileBuilder gfb(_gfs.get());
-        for (int i=0; i<DATA_LEN; i+=2)
-            gfb.appendChunk(DATA + i, min(2, DATA_LEN - i));
+        size_t totalSize = 0;
+        for (int i=0; i<DATA_LEN; i+=2) {
+            size_t chunkSize = min(2, DATA_LEN - i);
+            gfb.appendChunk(DATA + i, chunkSize);
+            totalSize += chunkSize;
+        }
         gfb.buildFile(DATA_NAME);
         GridFile gf = _gfs->findFileByName(DATA_NAME);
         ASSERT_EQUALS(gf.getNumChunks(), 1);
+        ASSERT_EQUALS(gf.getContentLength(), totalSize);
     }
 
     TEST_F(GridFSTest, GridFileBuilderMultipleChunks) {
         _gfs->setChunkSize(1);
         GridFileBuilder gfb(_gfs.get());
-        for (int i=0; i<DATA_LEN; i+=2)
-            gfb.appendChunk(DATA + i, min(2, DATA_LEN - i));
+        size_t total_size = 0;
+        for (int i=0; i<DATA_LEN; i+=2) {
+            size_t chunk_size = min(2, DATA_LEN - i);
+            gfb.appendChunk(DATA + i, chunk_size);
+            total_size += chunk_size;
+        }
         gfb.buildFile(DATA_NAME);
         GridFile gf = _gfs->findFileByName(DATA_NAME);
         ASSERT_EQUALS(gf.getNumChunks(), DATA_LEN);
+        ASSERT_EQUALS(gf.getContentLength(), total_size);
+    }
+
+    TEST_F(GridFSTest, GridFileBuilderAcrossChunkBoundry) {
+        _gfs->setChunkSize(11);
+        GridFileBuilder gfb(_gfs.get());
+        size_t total_size = 0;
+        for (int i=0; i<DATA_LEN; i+=2) {
+            size_t chunk_size = min(2, DATA_LEN - i);
+            gfb.appendChunk(DATA + i, chunk_size);
+            total_size += chunk_size;
+        }
+        gfb.buildFile(DATA_NAME);
+        GridFile gf = _gfs->findFileByName(DATA_NAME);
+        ASSERT_EQUALS(gf.getContentLength(), total_size);
     }
 
 } // namespace