src/common/dynamic-buffer.c

   1 /*
   2  * Copyright (C) 2017 Jérémie Galarneau <jeremie.galarneau@efficios.com>
   3  *
   4  * SPDX-License-Identifier: LGPL-2.1-only
   5  *
   6  */
   7
   8 #include <common/dynamic-buffer.h>
   9 #include <common/buffer-view.h>
  10 #include <common/utils.h>
  11
  12 /*
  13  * Round to (upper) power of two, val is returned if it already is a power of
  14  * two.
  15  */
  16 static
  17 size_t round_to_power_of_2(size_t val)
  18 {
  19         size_t rounded;
  20         const int order = utils_get_count_order_u64(val);
  21
  22         LTTNG_ASSERT(order >= 0);
  23         rounded = (1ULL << order);
  24         LTTNG_ASSERT(rounded >= val);
  25
  26         return rounded;
  27 }
  28
  29 LTTNG_HIDDEN
  30 void lttng_dynamic_buffer_init(struct lttng_dynamic_buffer *buffer)
  31 {
  32         LTTNG_ASSERT(buffer);
  33         memset(buffer, 0, sizeof(*buffer));
  34 }
  35
  36 LTTNG_HIDDEN
  37 int lttng_dynamic_buffer_append(struct lttng_dynamic_buffer *buffer,
  38                 const void *buf, size_t len)
  39 {
  40         int ret = 0;
  41
  42         if (!buffer || (!buf && len)) {
  43                 ret = -1;
  44                 goto end;
  45         }
  46
  47         if (len == 0) {
  48                 /* Not an error, no-op. */
  49                 goto end;
  50         }
  51
  52         LTTNG_ASSERT(buffer->_capacity >= buffer->size);
  53         if (buffer->_capacity < (len + buffer->size)) {
  54                 ret = lttng_dynamic_buffer_set_capacity(buffer,
  55                                 buffer->_capacity +
  56                                 (len - (buffer->_capacity - buffer->size)));
  57                 if (ret) {
  58                         goto end;
  59                 }
  60         }
  61
  62         memcpy(buffer->data + buffer->size, buf, len);
  63         buffer->size += len;
  64 end:
  65         return ret;
  66 }
  67
  68 LTTNG_HIDDEN
  69 int lttng_dynamic_buffer_append_buffer(struct lttng_dynamic_buffer *dst_buffer,
  70                 const struct lttng_dynamic_buffer *src_buffer)
  71 {
  72         int ret;
  73
  74         if (!dst_buffer || !src_buffer) {
  75                 ret = -1;
  76                 goto end;
  77         }
  78
  79         ret = lttng_dynamic_buffer_append(dst_buffer, src_buffer->data,
  80                         src_buffer->size);
  81 end:
  82         return ret;
  83 }
  84
  85 LTTNG_HIDDEN
  86 int lttng_dynamic_buffer_append_view(struct lttng_dynamic_buffer *buffer,
  87                 const struct lttng_buffer_view *src)
  88 {
  89         int ret;
  90
  91         if (!buffer || !src) {
  92                 ret = -1;
  93                 goto end;
  94         }
  95
  96         ret = lttng_dynamic_buffer_append(buffer, src->data,
  97                         src->size);
  98 end:
  99         return ret;
 100 }
 101
 102 LTTNG_HIDDEN
 103 int lttng_dynamic_buffer_set_size(struct lttng_dynamic_buffer *buffer,
 104                 size_t new_size)
 105 {
 106         int ret = 0;
 107
 108         if (!buffer) {
 109                 goto end;
 110         }
 111
 112         if (new_size == buffer->size) {
 113                 goto end;
 114         }
 115
 116         if (new_size > buffer->_capacity) {
 117                 ret = lttng_dynamic_buffer_set_capacity(buffer, new_size);
 118                 if (ret) {
 119                         goto end;
 120                 }
 121
 122                 memset(buffer->data + buffer->size, 0, new_size - buffer->size);
 123         } else if (new_size > buffer->size) {
 124                 memset(buffer->data + buffer->size, 0, new_size - buffer->size);
 125         } else {
 126                 /*
 127                  * Shrinking size. There is no need to zero-out the newly
 128                  * released memory as it will either be:
 129                  *   - overwritten by lttng_dynamic_buffer_append,
 130                  *   - expanded later, which will zero-out the memory
 131                  *
 132                  * Users of external APIs are encouraged to set the buffer's
 133                  * size _before_ making such calls.
 134                  */
 135         }
 136
 137         buffer->size = new_size;
 138 end:
 139         return ret;
 140 }
 141
 142 LTTNG_HIDDEN
 143 int lttng_dynamic_buffer_set_capacity(struct lttng_dynamic_buffer *buffer,
 144                 size_t demanded_capacity)
 145 {
 146         int ret = 0;
 147         void *new_buf;
 148         size_t new_capacity = demanded_capacity ?
 149                         round_to_power_of_2(demanded_capacity) : 0;
 150
 151         if (!buffer || demanded_capacity < buffer->size) {
 152                 /*
 153                  * Shrinking a buffer's size by changing its capacity is
 154                  * unsupported.
 155                  */
 156                 ret = -1;
 157                 goto end;
 158         }
 159
 160         if (new_capacity == buffer->_capacity) {
 161                 goto end;
 162         }
 163
 164         /* Memory is initialized by the size increases. */
 165         new_buf = realloc(buffer->data, new_capacity);
 166         if (!new_buf) {
 167                 ret = -1;
 168                 goto end;
 169         }
 170
 171         buffer->data = new_buf;
 172         buffer->_capacity = new_capacity;
 173 end:
 174         return ret;
 175 }
 176
 177 /* Release any memory used by the dynamic buffer. */
 178 LTTNG_HIDDEN
 179 void lttng_dynamic_buffer_reset(struct lttng_dynamic_buffer *buffer)
 180 {
 181         if (!buffer) {
 182                 return;
 183         }
 184
 185         buffer->size = 0;
 186         buffer->_capacity = 0;
 187         free(buffer->data);
 188         buffer->data = NULL;
 189 }
 190
 191 LTTNG_HIDDEN
 192 size_t lttng_dynamic_buffer_get_capacity_left(
 193                 struct lttng_dynamic_buffer *buffer)
 194 {
 195         if (!buffer) {
 196                 return 0;
 197         }
 198
 199         return buffer->_capacity - buffer->size;
 200 }