Introduce a flag in SourceManager to treat non-system source files

as "volatile", meaning there's a high enough chance that they may
change while we are trying to use them.

This flag is only enabled by libclang.
Currently "volatile" source files will be stat'ed immediately
before opening them, because the file size stat info
may not be accurate since when we got it (e.g. from the PCH).
This avoids crashes when trying to reference mmap'ed memory
from a file whose size is not what we expect.

Note that there's still a window for a racing issue to occur
but the window for it should be way smaller than before.
We can consider later on to avoid mmap completely on such files.

rdar://11612916

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@160074 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 12 insertions, 3 deletions

diff --git a/include/clang/Frontend/ASTUnit.h b/include/clang/Frontend/ASTUnit.h
index afaf60e89a..8dd863e304 100644
--- a/include/clang/Frontend/ASTUnit.h
+++ b/include/clang/Frontend/ASTUnit.h
@@ -254,6 +254,10 @@ private:
   /// \brief Whether to include brief documentation within the set of code
   /// completions cached.
   bool IncludeBriefCommentsInCodeCompletion : 1;
+
+  /// \brief True if non-system source files should be treated as volatile
+  /// (likely to change while trying to use them).
+  bool UserFilesAreVolatile : 1;
  
   /// \brief The language options used when we load an AST file.
   LangOptions ASTFileLangOpts;
@@ -619,7 +623,8 @@ public:
   /// \brief Create a ASTUnit. Gets ownership of the passed CompilerInvocation. 
   static ASTUnit *create(CompilerInvocation *CI,
                          IntrusiveRefCntPtr<DiagnosticsEngine> Diags,
-                         bool CaptureDiagnostics = false);
+                         bool CaptureDiagnostics,
+                         bool UserFilesAreVolatile);
 
   /// \brief Create a ASTUnit from an AST file.
   ///
@@ -636,7 +641,8 @@ public:
                                   RemappedFile *RemappedFiles = 0,
                                   unsigned NumRemappedFiles = 0,
                                   bool CaptureDiagnostics = false,
-                                  bool AllowPCHWithCompilerErrors = false);
+                                  bool AllowPCHWithCompilerErrors = false,
+                                  bool UserFilesAreVolatile = false);
 
 private:
   /// \brief Helper function for \c LoadFromCompilerInvocation() and
@@ -687,6 +693,7 @@ public:
                                              bool PrecompilePreamble = false,
                                        bool CacheCodeCompletionResults = false,
                               bool IncludeBriefCommentsInCodeCompletion = false,
+                                       bool UserFilesAreVolatile = false,
                                        OwningPtr<ASTUnit> *ErrAST = 0);
 
   /// LoadFromCompilerInvocation - Create an ASTUnit from a source file, via a
@@ -707,7 +714,8 @@ public:
                                              bool PrecompilePreamble = false,
                                       TranslationUnitKind TUKind = TU_Complete,
                                        bool CacheCodeCompletionResults = false,
-                            bool IncludeBriefCommentsInCodeCompletion = false);
+                            bool IncludeBriefCommentsInCodeCompletion = false,
+                                             bool UserFilesAreVolatile = false);
 
   /// LoadFromCommandLine - Create an ASTUnit from a vector of command line
   /// arguments, which must specify exactly one source file.
@@ -742,6 +750,7 @@ public:
                             bool IncludeBriefCommentsInCodeCompletion = false,
                                       bool AllowPCHWithCompilerErrors = false,
                                       bool SkipFunctionBodies = false,
+                                      bool UserFilesAreVolatile = false,
                                       OwningPtr<ASTUnit> *ErrAST = 0);
   
   /// \brief Reparse the source files using the same command-line options that