From: Jérémie Galarneau <jeremie.galarneau@efficios.com>
Date: Fri, 5 May 2017 02:49:35 +0000 (-0400)
Subject: Add lttng_buffer_view util
X-Git-Url: http://git.efficios.com/?p=lttng-tools.git;a=commitdiff_plain;h=01dc0eed91e5c7db3f12beda894cb3d9cc7a4fa1

Add lttng_buffer_view util

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>
---

diff --git a/src/common/Makefile.am b/src/common/Makefile.am
index f54f646c6..83354d070 100644
--- a/src/common/Makefile.am
+++ b/src/common/Makefile.am
@@ -73,7 +73,8 @@ libcommon_la_SOURCES = error.h error.c utils.c utils.h runas.c runas.h \
                        mi-lttng.h mi-lttng.c \
                        daemonize.c daemonize.h \
                        unix.c unix.h \
-                       dynamic-buffer.h dynamic-buffer.c
+                       dynamic-buffer.h dynamic-buffer.c \
+                       buffer-view.h buffer-view.c
 
 libcommon_la_LIBADD = \
 		$(top_builddir)/src/common/config/libconfig.la
diff --git a/src/common/buffer-view.c b/src/common/buffer-view.c
new file mode 100644
index 000000000..8ff153991
--- /dev/null
+++ b/src/common/buffer-view.c
@@ -0,0 +1,70 @@
+/*
+ * Copyright (C) 2017 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License, version 2.1 only,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <common/buffer-view.h>
+#include <common/dynamic-buffer.h>
+#include <common/macros.h>
+#include <common/error.h>
+#include <assert.h>
+
+struct lttng_buffer_view lttng_buffer_view_from_view(
+		const struct lttng_buffer_view *src, size_t offset,
+		ptrdiff_t len)
+{
+	struct lttng_buffer_view view = { .data = NULL, .size = 0 };
+
+	assert(src);
+
+	if (offset > src->size) {
+		ERR("Attempt to create buffer view with invalid offset");
+		goto end;
+	}
+
+	if (len != -1 && len > (src->size - offset)) {
+		ERR("Attempt to create buffer view with invalid length");
+		goto end;
+	}
+
+	view.data = src->data + offset;
+	view.size = len == -1 ? (src->size - offset) : len;
+end:
+	return view;
+}
+
+struct lttng_buffer_view lttng_buffer_view_from_dynamic_buffer(
+		const struct lttng_dynamic_buffer *src, size_t offset,
+		ptrdiff_t len)
+{
+	struct lttng_buffer_view view = { .data = NULL, .size = 0 };
+
+	assert(src);
+
+	if (offset > src->size) {
+		ERR("Attempt to create buffer view with invalid offset");
+		goto end;
+	}
+
+	if (len != -1 && len > (src->size - offset)) {
+		ERR("Attempt to create buffer view with invalid length");
+		goto end;
+	}
+
+	view.data = src->data + offset;
+	view.size = len == -1 ? (src->size - offset) : len;
+end:
+	return view;
+}
diff --git a/src/common/buffer-view.h b/src/common/buffer-view.h
new file mode 100644
index 000000000..7d03b41dd
--- /dev/null
+++ b/src/common/buffer-view.h
@@ -0,0 +1,65 @@
+/*
+ * Copyright (C) 2017 - Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License, version 2.1 only,
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef LTTNG_BUFFER_VIEW_H
+#define LTTNG_BUFFER_VIEW_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+struct lttng_dynamic_buffer;
+
+struct lttng_buffer_view {
+	const char *data;
+	size_t size;
+};
+
+/**
+ * Return a buffer view referencing a subset of the memory referenced by another
+ * view.
+ *
+ * @src		Source view to reference
+ * @offset	Offset to apply to the source memory content
+ * @len		Length of the memory contents to reference. Passing -1 will
+ *		cause the view to reference the whole view from the offset
+ *		provided.
+ *
+ * Note that a buffer view never assumes the ownership of the memory it
+ * references.
+ */
+struct lttng_buffer_view lttng_buffer_view_from_view(
+		const struct lttng_buffer_view *src, size_t offset,
+		ptrdiff_t len);
+
+/**
+ * Return a buffer view referencing a subset of the memory referenced by a
+ * dynamic buffer.
+ *
+ * @src		Source dynamic buffer to reference
+ * @offset	Offset to apply to the source memory content
+ * @len		Length of the memory contents to reference. Passing -1 will
+ *		cause the view to reference the whole dynamic buffer from the
+ *		offset provided.
+ *
+ * Note that a buffer view never assumes the ownership of the memory it
+ * references.
+ */
+struct lttng_buffer_view lttng_buffer_view_from_dynamic_buffer(
+		const struct lttng_dynamic_buffer *src, size_t offset,
+		ptrdiff_t len);
+
+#endif /* LTTNG_BUFFER_VIEW_H */