Rename C++ header files to .hpp

[lttng-tools.git] / src / common / dynamic-buffer.hpp

diff --git a/src/common/dynamic-buffer.hpp b/src/common/dynamic-buffer.hpp
new file mode 100644 (file)
index 0000000..65b1575
--- /dev/null
+++ b/src/common/dynamic-buffer.hpp
@@ -0,0 +1,95 @@
+/*
+ * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ *
+ * SPDX-License-Identifier: LGPL-2.1-only
+ *
+ */
+
+#ifndef LTTNG_DYNAMIC_BUFFER_H
+#define LTTNG_DYNAMIC_BUFFER_H
+
+#include <stddef.h>
+#include <stdint.h>
+#include <common/macros.hpp>
+
+struct lttng_buffer_view;
+
+struct lttng_dynamic_buffer {
+       char *data;
+       /* size is the buffer's currently used capacity. */
+       size_t size;
+       /*
+        * capacity shall not be accessed by users directly, it is meant for
+        * internal use only.
+        */
+       size_t _capacity;
+};
+
+/*
+ * Initialize a dynamic buffer. This performs no allocation and is meant
+ * to be used instead of memset or explicit initialization of the buffer.
+ */
+void lttng_dynamic_buffer_init(struct lttng_dynamic_buffer *buffer);
+
+/*
+ * Append the content of a raw memory buffer to the end of a dynamic buffer
+ * (after its current "size"). The dynamic buffer's size is increased by
+ * "len", and its capacity is adjusted automatically.
+ */
+int lttng_dynamic_buffer_append(struct lttng_dynamic_buffer *buffer,
+               const void *buf, size_t len);
+
+/*
+ * Performs the same action as lttng_dynamic_buffer_append(), but using another
+ * dynamic buffer as the source buffer. The source buffer's size is used in lieu
+ * of "len".
+ */
+int lttng_dynamic_buffer_append_buffer(struct lttng_dynamic_buffer *dst_buffer,
+               const struct lttng_dynamic_buffer *src_buffer);
+
+/*
+ * Performs the same action as lttng_dynamic_buffer_append(), but using a
+ * buffer view as the source buffer. The source buffer's size is used in lieu
+ * of "len".
+ */
+int lttng_dynamic_buffer_append_view(struct lttng_dynamic_buffer *buffer,
+               const struct lttng_buffer_view *view);
+
+/*
+ * Set the buffer's size to new_size. The capacity of the buffer will
+ * be expanded (if necessary) to accommodates new_size. Areas acquired by
+ * a size increase will be zeroed.
+ *
+ * Be careful to expand the buffer's size _before_ calling out external
+ * APIs (e.g. read(3)) which may populate the buffer as setting the size
+ * after will zero-out the result of the operation.
+ *
+ * Shrinking a buffer does not zero the old content. If the buffer may contain
+ * sensititve information, it must be cleared manually _before_ changing the
+ * size.
+ *
+ * NOTE: It is striclty _invalid_ to access memory after _size_, regardless
+ *       of prior calls to set_capacity().
+ */
+int lttng_dynamic_buffer_set_size(struct lttng_dynamic_buffer *buffer,
+               size_t new_size);
+
+/*
+ * Set the buffer's capacity to accommodates the new_capacity, allocating memory
+ * as necessary. The buffer's content is preserved. Setting a buffer's capacity
+ * is meant as a _hint_ to the underlying buffer and is only optimization; no
+ * guarantee is offered that subsequent calls to append or set_size will succeed.
+ *
+ * If the current size > new_capacity, the operation will fail.
+ */
+int lttng_dynamic_buffer_set_capacity(struct lttng_dynamic_buffer *buffer,
+               size_t new_capacity);
+
+/* Release any memory used by the dynamic buffer. */
+void lttng_dynamic_buffer_reset(struct lttng_dynamic_buffer *buffer);
+
+/* Get the space left in the buffer before a new resize is needed. */
+size_t lttng_dynamic_buffer_get_capacity_left(
+               struct lttng_dynamic_buffer *buffer);
+
+#endif /* LTTNG_DYNAMIC_BUFFER_H */