common: compile libcommon as C++

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

diff --git a/src/common/dynamic-buffer.cpp b/src/common/dynamic-buffer.cpp
new file mode 100644 (file)
index 0000000..945434c
--- /dev/null
+++ b/src/common/dynamic-buffer.cpp
@@ -0,0 +1,192 @@
+/*
+ * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ *
+ * SPDX-License-Identifier: LGPL-2.1-only
+ *
+ */
+
+#include <common/dynamic-buffer.h>
+#include <common/buffer-view.h>
+#include <common/utils.h>
+
+/*
+ * Round to (upper) power of two, val is returned if it already is a power of
+ * two.
+ */
+static
+size_t round_to_power_of_2(size_t val)
+{
+       size_t rounded;
+       const int order = utils_get_count_order_u64(val);
+
+       LTTNG_ASSERT(order >= 0);
+       rounded = (1ULL << order);
+       LTTNG_ASSERT(rounded >= val);
+
+       return rounded;
+}
+
+void lttng_dynamic_buffer_init(struct lttng_dynamic_buffer *buffer)
+{
+       LTTNG_ASSERT(buffer);
+       memset(buffer, 0, sizeof(*buffer));
+}
+
+int lttng_dynamic_buffer_append(struct lttng_dynamic_buffer *buffer,
+               const void *buf, size_t len)
+{
+       int ret = 0;
+
+       if (!buffer || (!buf && len)) {
+               ret = -1;
+               goto end;
+       }
+
+       if (len == 0) {
+               /* Not an error, no-op. */
+               goto end;
+       }
+
+       LTTNG_ASSERT(buffer->_capacity >= buffer->size);
+       if (buffer->_capacity < (len + buffer->size)) {
+               ret = lttng_dynamic_buffer_set_capacity(buffer,
+                               buffer->_capacity +
+                               (len - (buffer->_capacity - buffer->size)));
+               if (ret) {
+                       goto end;
+               }
+       }
+
+       memcpy(buffer->data + buffer->size, buf, len);
+       buffer->size += len;
+end:
+       return ret;
+}
+
+int lttng_dynamic_buffer_append_buffer(struct lttng_dynamic_buffer *dst_buffer,
+               const struct lttng_dynamic_buffer *src_buffer)
+{
+       int ret;
+
+       if (!dst_buffer || !src_buffer) {
+               ret = -1;
+               goto end;
+       }
+
+       ret = lttng_dynamic_buffer_append(dst_buffer, src_buffer->data,
+                       src_buffer->size);
+end:
+       return ret;
+}
+
+int lttng_dynamic_buffer_append_view(struct lttng_dynamic_buffer *buffer,
+               const struct lttng_buffer_view *src)
+{
+       int ret;
+
+       if (!buffer || !src) {
+               ret = -1;
+               goto end;
+       }
+
+       ret = lttng_dynamic_buffer_append(buffer, src->data,
+                       src->size);
+end:
+       return ret;
+}
+
+int lttng_dynamic_buffer_set_size(struct lttng_dynamic_buffer *buffer,
+               size_t new_size)
+{
+       int ret = 0;
+
+       if (!buffer) {
+               goto end;
+       }
+
+       if (new_size == buffer->size) {
+               goto end;
+       }
+
+       if (new_size > buffer->_capacity) {
+               ret = lttng_dynamic_buffer_set_capacity(buffer, new_size);
+               if (ret) {
+                       goto end;
+               }
+
+               memset(buffer->data + buffer->size, 0, new_size - buffer->size);
+       } else if (new_size > buffer->size) {
+               memset(buffer->data + buffer->size, 0, new_size - buffer->size);
+       } else {
+               /*
+                * Shrinking size. There is no need to zero-out the newly
+                * released memory as it will either be:
+                *   - overwritten by lttng_dynamic_buffer_append,
+                *   - expanded later, which will zero-out the memory
+                *
+                * Users of external APIs are encouraged to set the buffer's
+                * size _before_ making such calls.
+                */
+       }
+
+       buffer->size = new_size;
+end:
+       return ret;
+}
+
+int lttng_dynamic_buffer_set_capacity(struct lttng_dynamic_buffer *buffer,
+               size_t demanded_capacity)
+{
+       int ret = 0;
+       void *new_buf;
+       size_t new_capacity = demanded_capacity ?
+                       round_to_power_of_2(demanded_capacity) : 0;
+
+       if (!buffer || demanded_capacity < buffer->size) {
+               /*
+                * Shrinking a buffer's size by changing its capacity is
+                * unsupported.
+                */
+               ret = -1;
+               goto end;
+       }
+
+       if (new_capacity == buffer->_capacity) {
+               goto end;
+       }
+
+       /* Memory is initialized by the size increases. */
+       new_buf = realloc(buffer->data, new_capacity);
+       if (!new_buf) {
+               ret = -1;
+               goto end;
+       }
+
+       buffer->data = (char *) new_buf;
+       buffer->_capacity = new_capacity;
+end:
+       return ret;
+}
+
+/* Release any memory used by the dynamic buffer. */
+void lttng_dynamic_buffer_reset(struct lttng_dynamic_buffer *buffer)
+{
+       if (!buffer) {
+               return;
+       }
+
+       buffer->size = 0;
+       buffer->_capacity = 0;
+       free(buffer->data);
+       buffer->data = NULL;
+}
+
+size_t lttng_dynamic_buffer_get_capacity_left(
+               struct lttng_dynamic_buffer *buffer)
+{
+       if (!buffer) {
+               return 0;
+       }
+
+       return buffer->_capacity - buffer->size;
+}