memcheck: fix race in libgit2...

...caused by incorrectly setting and resetting the library internal
state and the misuse of pthreads in libgit2.

Normally, git_libgit2_init and git_libgit2_shutdown should span the
life of a worker thread in order to be safely used. However, due to
an incorrect implementation of libgit2's threadstate with pthreads,
on unix systems there is a race condition.

Until the use of pthread_key_t is corrected in libgit2, we need to
apply a workaround by always ensuring that the main thread is the
first thread reaching the GitContext constructor.

1 files changed, 2 insertions, 1 deletions

diff --git a/src/buildtool/file_system/git_context.hpp b/src/buildtool/file_system/git_context.hpp
index d6aaeab6..8cec02db 100644
--- a/src/buildtool/file_system/git_context.hpp
+++ b/src/buildtool/file_system/git_context.hpp
@@ -26,10 +26,11 @@ class GitContext {
     auto operator=(GitContext const&) = delete;
     auto operator=(GitContext&& other) = delete;
 
-    GitContext() noexcept;
+    static void Create() noexcept;
     ~GitContext() noexcept;
 
   private:
+    GitContext() noexcept;
     bool initialized_{false};
 };