From 5966417eba59c9014c1f67ae37257e7266e647b5 Mon Sep 17 00:00:00 2001 From: =?utf8?q?J=C3=A9r=C3=A9mie=20Galarneau?= Date: Thu, 4 May 2017 22:48:25 -0400 Subject: [PATCH] Add lttng_dynamic_buffer util MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Signed-off-by: Jérémie Galarneau --- src/common/Makefile.am | 2 +- src/common/dynamic-buffer.c | 181 ++++++++++++++++++++++++++++++++++++ src/common/dynamic-buffer.h | 62 ++++++++++++ 3 files changed, 244 insertions(+), 1 deletion(-) create mode 100644 src/common/dynamic-buffer.c create mode 100644 src/common/dynamic-buffer.h diff --git a/src/common/Makefile.am b/src/common/Makefile.am index 8619b5e25..f54f646c6 100644 --- a/src/common/Makefile.am +++ b/src/common/Makefile.am @@ -73,7 +73,7 @@ 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 \ - filter.c filter.h context.c context.h + dynamic-buffer.h dynamic-buffer.c libcommon_la_LIBADD = \ $(top_builddir)/src/common/config/libconfig.la diff --git a/src/common/dynamic-buffer.c b/src/common/dynamic-buffer.c new file mode 100644 index 000000000..ea26a51ac --- /dev/null +++ b/src/common/dynamic-buffer.c @@ -0,0 +1,181 @@ +/* + * Copyright (C) 2017 - Jérémie Galarneau + * + * 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 +#include +#include +#include + +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); +} diff --git a/src/common/dynamic-buffer.h b/src/common/dynamic-buffer.h new file mode 100644 index 000000000..19097f927 --- /dev/null +++ b/src/common/dynamic-buffer.h @@ -0,0 +1,62 @@ +/* + * Copyright (C) 2017 - Jérémie Galarneau + * + * 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 +#include + +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 */ -- 2.34.1