Avoid a potential race between stat() and open() of ASTFile
We need to open an ASTFile while checking its expected size and
modification time, or another clang instance can modify the file between
the stat() and the open().
llvm-svn: 207735
diff --git a/clang/lib/Serialization/ModuleManager.cpp b/clang/lib/Serialization/ModuleManager.cpp
index c36d902..9b3159e 100644
--- a/clang/lib/Serialization/ModuleManager.cpp
+++ b/clang/lib/Serialization/ModuleManager.cpp
@@ -381,7 +381,9 @@
off_t ExpectedSize,
time_t ExpectedModTime,
const FileEntry *&File) {
- File = FileMgr.getFile(FileName, /*openFile=*/false, /*cacheFailure=*/false);
+ // Open the file immediately to ensure there is no race between stat'ing and
+ // opening the file.
+ File = FileMgr.getFile(FileName, /*openFile=*/true, /*cacheFailure=*/false);
if (!File && FileName != "-") {
return false;
@@ -389,6 +391,8 @@
if ((ExpectedSize && ExpectedSize != File->getSize()) ||
(ExpectedModTime && ExpectedModTime != File->getModificationTime())) {
+ FileMgr.invalidateCache(File);
+ File = nullptr;
return true;
}