--- /dev/null
+/*
+ * 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/dynamic-buffer.h>
+#include <common/macros.h>
+#include <common/utils.h>
+#include <assert.h>
+
+static
+size_t round_to_power_of_2(size_t val)
+{
+ int order;
+ size_t rounded;
+
+ order = utils_get_count_order_u64(val);
+ assert(order >= 0);
+ rounded = (1ULL << order);
+ assert(rounded >= val);
+
+ return rounded;
+}
+
+void lttng_dynamic_buffer_init(struct lttng_dynamic_buffer *buffer)
+{
+ 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;
+ }
+
+ if ((buffer->capacity - buffer->size) < len) {
+ 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,
+ 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_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;
+ }
+ } 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 new_capacity)
+{
+ int ret = 0;
+ size_t rounded_capacity = round_to_power_of_2(new_capacity);
+
+ if (!buffer || new_capacity < buffer->size) {
+ ret = -1;
+ goto end;
+ }
+
+ if (rounded_capacity == buffer->capacity) {
+ goto end;
+ }
+
+ if (!buffer->data) {
+ buffer->data = zmalloc(rounded_capacity);
+ if (!buffer->data) {
+ ret = -1;
+ goto end;
+ }
+ } else {
+ void *new_buf;
+
+ new_buf = realloc(buffer->data, rounded_capacity);
+ if (new_buf) {
+ if (rounded_capacity > buffer->capacity) {
+ memset(new_buf + buffer->capacity, 0,
+ rounded_capacity - buffer->capacity);
+ }
+ } else {
+ /* Realloc failed, try to acquire a new block. */
+ new_buf = zmalloc(rounded_capacity);
+ if (!new_buf) {
+ ret = -1;
+ goto end;
+ }
+ memcpy(new_buf, buffer->data, buffer->size);
+ free(buffer->data);
+ }
+ buffer->data = new_buf;
+ }
+ buffer->capacity = rounded_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);
+}
--- /dev/null
+/*
+ * 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_DYNAMIC_BUFFER_H
+#define LTTNG_DYNAMIC_BUFFER_H
+
+#include <stddef.h>
+#include <stdint.h>
+
+struct lttng_dynamic_buffer {
+ char *data;
+ size_t size;
+ size_t capacity;
+};
+
+void lttng_dynamic_buffer_init(struct lttng_dynamic_buffer *buffer);
+
+int lttng_dynamic_buffer_append(struct lttng_dynamic_buffer *buffer,
+ const void *buf, size_t len);
+
+int lttng_dynamic_buffer_append_buffer(struct lttng_dynamic_buffer *dst_buffer,
+ struct lttng_dynamic_buffer *src_buffer);
+
+/*
+ * Set the buffer's size to new_size. The capacity of the buffer will
+ * be expanded (if necessary) to accomodate new_size. Areas acquired by
+ * an enlarging new_size _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.
+ */
+int lttng_dynamic_buffer_set_size(struct lttng_dynamic_buffer *buffer,
+ size_t new_size);
+
+/*
+ * Set the buffer's capacity to accomodate the new_capacity, allocating memory
+ * as necessary. The buffer's content is preserved.
+ *
+ * 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);
+
+#endif /* LTTNG_DYNAMIC_BUFFER_H */
projects / lttng-tools.git / commitdiff
