[ostree] repo: Add ostree_repo_get_dfd()

[Colin Walters <walters src gnome org>]

commit 3efdcb54b79b288a208e5d41b4d16c2f445cc664
Author: Colin Walters <walters verbum org>
Date:   Tue Mar 1 21:52:22 2016 -0500

    repo: Add ostree_repo_get_dfd()
    
    I plan to use this in rpm-ostree at least for two reasons:
     - To find the mtime on the repo
     - To use the tmp/ directory to stage content (but we should eventually
       add a better API)

 src/libostree/libostree.sym |    5 +++++
 src/libostree/ostree-repo.c |   18 ++++++++++++++++++
 src/libostree/ostree-repo.h |    3 +++
 3 files changed, 26 insertions(+), 0 deletions(-)
---
diff --git a/src/libostree/libostree.sym b/src/libostree/libostree.sym
index ee6c2e7..ce8861f 100644
--- a/src/libostree/libostree.sym
+++ b/src/libostree/libostree.sym
@@ -311,3 +311,8 @@ global:
 local:
        *;
 };
+
+LIBOSTREE_2016.4 {
+global:
+        ostree_repo_get_dfd;
+} LIBOSTREE_2016.3;
diff --git a/src/libostree/ostree-repo.c b/src/libostree/ostree-repo.c
index 3b08d44..752e097 100644
--- a/src/libostree/ostree-repo.c
+++ b/src/libostree/ostree-repo.c
@@ -2423,6 +2423,24 @@ ostree_repo_get_path (OstreeRepo  *self)
   return self->repodir;
 }
 
+/**
+ * ostree_repo_get_dfd:
+ * @self: Repo
+ *
+ * In some cases it's useful for applications to access the repository
+ * directly; for example, writing content into `repo/tmp` ensures it's
+ * on the same filesystem.  Another case is detecting the mtime on the
+ * repository (to see whether a ref was written).
+ *
+ * Returns: File descriptor for repository root - owned by @self
+ */
+int
+ostree_repo_get_dfd (OstreeRepo  *self)
+{
+  g_return_val_if_fail (self->repo_dir_fd != -1, -1);
+  return self->repo_dir_fd;
+}
+
 OstreeRepoMode
 ostree_repo_get_mode (OstreeRepo  *self)
 {
diff --git a/src/libostree/ostree-repo.h b/src/libostree/ostree-repo.h
index 288dca0..b8399b1 100644
--- a/src/libostree/ostree-repo.h
+++ b/src/libostree/ostree-repo.h
@@ -83,6 +83,9 @@ _OSTREE_PUBLIC
 GFile *       ostree_repo_get_path (OstreeRepo  *self);
 
 _OSTREE_PUBLIC
+int           ostree_repo_get_dfd (OstreeRepo  *self);
+
+_OSTREE_PUBLIC
 OstreeRepoMode ostree_repo_get_mode (OstreeRepo  *self);
 
 _OSTREE_PUBLIC