Allow direct access to the dirfd of a directory handle

[lttng-tools.git] / src / common / compat / directory-handle.h

diff --git a/src/common/compat/directory-handle.h b/src/common/compat/directory-handle.h
index 7d2cab339fc28ad15752d6a2652679e3a7df359e..605c3dc814743e3ab43a3d206f4f87436a9b7da6 100644 (file)
--- a/src/common/compat/directory-handle.h
+++ b/src/common/compat/directory-handle.h
@@ -32,6 +32,14 @@
 struct lttng_directory_handle {
        int dirfd;
 };
+
+static inline
+int lttng_directory_handle_get_dirfd(
+               const struct lttng_directory_handle *handle)
+{
+       return handle->dirfd;
+}
+
 #else
 struct lttng_directory_handle {
        char *base_path;
@@ -40,9 +48,7 @@ struct lttng_directory_handle {
 
 /*
  * Initialize a directory handle to the provided path. Passing a NULL path
- * returns a handle to the current working directory. The working directory
- * is not sampled; it will be accessed at the time of use of the functions
- * of this API.
+ * returns a handle to the current working directory.
  *
  * An initialized directory handle must be finalized using
  * lttng_directory_handle_fini().
@@ -51,10 +57,58 @@ LTTNG_HIDDEN
 int lttng_directory_handle_init(struct lttng_directory_handle *handle,
                const char *path);
 
+/*
+ * Initialize a new directory handle to a path relative to an existing handle.
+ *
+ * The provided path must already exist. Note that the creation of a
+ * subdirectory and the creation of a handle are kept as separate operations
+ * to highlight the fact that there is an inherent race between the creation of
+ * a directory and the creation of a handle to it.
+ *
+ * Passing a NULL path effectively copies the original handle.
+ *
+ * An initialized directory handle must be finalized using
+ * lttng_directory_handle_fini().
+ */
+LTTNG_HIDDEN
+int lttng_directory_handle_init_from_handle(
+               struct lttng_directory_handle *new_handle,
+               const char *path,
+               const struct lttng_directory_handle *handle);
+
+/*
+ * Initialize a new directory handle from an existing directory fd.
+ *
+ * The new directory handle assumes the ownership of the directory fd.
+ * Note that this method should only be used in very specific cases, such as
+ * re-creating a directory handle from a dirfd passed over a unix socket.
+ *
+ * An initialized directory handle must be finalized using
+ * lttng_directory_handle_fini().
+ */
 LTTNG_HIDDEN
 int lttng_directory_handle_init_from_dirfd(
                struct lttng_directory_handle *handle, int dirfd);
 
+/*
+ * Copy a directory handle.
+ */
+LTTNG_HIDDEN
+int lttng_directory_handle_copy(const struct lttng_directory_handle *handle,
+               struct lttng_directory_handle *new_copy);
+
+/*
+ * Move a directory handle. The original directory handle may no longer be
+ * used after this call. This call cannot fail; directly assign the
+ * return value to the new directory handle.
+ *
+ * It is safe (but unnecessary) to call lttng_directory_handle_fini on the
+ * original handle.
+ */
+LTTNG_HIDDEN
+struct lttng_directory_handle
+lttng_directory_handle_move(struct lttng_directory_handle *original);
+
 /*
  * Release the resources of a directory handle.
  */