tqcq/leveldb
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

Always copy bytes to scratch buffer when reading w/MemEnv.

Browse Source 
FileState::Read (used by InMemoryEnv) creates a new Slice when reading.
If all the bytes for the read are in the first block then the Slice
points to the private block data in FileState and is not copied to the
|scratch| buffer.

A recent change allows files in InMemEnv to be overwritten which deletes
these blocks and in this case can result in a Slice having a dangling
pointer. This change fixes this bug by always copying to the |scratch|
buffer.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=239301930
This commit is contained in:
cmumford 2019-03-19 17:10:56 -07:00 committed by Victor Costan
parent 201f77d137
commit ce399ac28a
1 changed files with 0 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
helpers/memenv/memenv.cc
View File

@ -82,13 +82,6 @@ class FileState {
assert(offset / kBlockSize <= std::numeric_limits<size_t>::max());
size_t block = static_cast<size_t>(offset / kBlockSize);
size_t block_offset = offset % kBlockSize;
if (n <= kBlockSize - block_offset) {
// The requested bytes are all in the first block.
*result = Slice(blocks_[block] + block_offset, n);
return Status::OK();
}
size_t bytes_to_copy = n;
char* dst = scratch;