Rename C++ header files to .hpp

[lttng-tools.git] / src / common / fs-handle.hpp

diff --git a/src/common/fs-handle.hpp b/src/common/fs-handle.hpp
new file mode 100644 (file)
index 0000000..8b3a882
--- /dev/null
+++ b/src/common/fs-handle.hpp
@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2020 Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ *
+ * SPDX-License-Identifier: LGPL-2.1-only
+ *
+ */
+
+#ifndef FS_HANDLE_H
+#define FS_HANDLE_H
+
+#include <common/macros.hpp>
+#include <stdio.h>
+
+struct fs_handle;
+
+/*
+ * Marks the handle as the most recently used and marks the 'fd' as
+ * "in-use". This prevents the tracker from recycling the underlying
+ * file descriptor while it is actively being used by a thread.
+ *
+ * Don't forget that the tracker may be initiating an fd 'suspension'
+ * from another thread as the need to free an fd slot may arise from any
+ * thread within the daemon.
+ *
+ * Note that a restorable fd should never be held for longer than
+ * strictly necessary (e.g. the duration of a syscall()).
+ *
+ * Returns the fd on success, otherwise a negative value may be returned
+ * if the restoration of the fd failed.
+ */
+int fs_handle_get_fd(struct fs_handle *handle);
+
+/*
+ * Used by the caller to signal that it is no longer using the underlying fd and
+ * that it may be safely suspended.
+ */
+void fs_handle_put_fd(struct fs_handle *handle);
+
+/*
+ * Unlink the file associated to an fs_handle. Note that the unlink
+ * operation will not be performed immediately. It will only be performed
+ * once all references to the underlying file (through other fs_handle objects)
+ * have been released.
+ *
+ * However, note that the file will be renamed so as to provide the observable
+ * effect of an unlink(), that is removing a name from the filesystem.
+ *
+ * Returns 0 on success, otherwise a negative value will be returned
+ * if the operation failed.
+ */
+int fs_handle_unlink(struct fs_handle *handle);
+
+/*
+ * Frees the handle and discards the underlying fd.
+ */
+int fs_handle_close(struct fs_handle *handle);
+
+ssize_t fs_handle_read(struct fs_handle *handle, void *buf, size_t count);
+
+ssize_t fs_handle_write(struct fs_handle *handle, const void *buf, size_t count);
+
+int fs_handle_truncate(struct fs_handle *handle, off_t offset);
+
+off_t fs_handle_seek(struct fs_handle *handle, off_t offset, int whence);
+
+#endif /* FS_HANDLE_H */