Fix: memory is not zeroed on first set_capacity

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

diff --git a/src/common/dynamic-buffer.c b/src/common/dynamic-buffer.c
index fd39f813b3c2568beec2dff1be91343161ec8517..aef80dded0bab2785820f7cf8acb1f7b9071cf7b 100644 (file)
--- a/src/common/dynamic-buffer.c
+++ b/src/common/dynamic-buffer.c
@@ -108,22 +108,12 @@ int lttng_dynamic_buffer_set_size(struct lttng_dynamic_buffer *buffer,
        }
 
        if (new_size > buffer->_capacity) {
-               size_t original_size = buffer->size;
-               size_t original_capacity = buffer->_capacity;
-
                ret = lttng_dynamic_buffer_set_capacity(buffer, new_size);
                if (ret) {
                        goto end;
                }
 
-               /*
-                * Zero-initialize the space that was left in the buffer at the
-                * before we increased its capacity (original capacity - original size).
-                * The newly acquired capacity (new capacity - original capacity)
-                * is zeroed by lttng_dynamic_buffer_set_capacity().
-                */
-               memset(buffer->data + original_size, 0,
-                               original_capacity - original_size);
+               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 {
@@ -148,7 +138,8 @@ int lttng_dynamic_buffer_set_capacity(struct lttng_dynamic_buffer *buffer,
 {
        int ret = 0;
        void *new_buf;
-       size_t new_capacity = round_to_power_of_2(demanded_capacity);
+       size_t new_capacity = demanded_capacity ?
+                       round_to_power_of_2(demanded_capacity) : 0;
 
        if (!buffer || demanded_capacity < buffer->size) {
                /*
@@ -186,3 +177,13 @@ void lttng_dynamic_buffer_reset(struct lttng_dynamic_buffer *buffer)
        buffer->_capacity = 0;
        free(buffer->data);
 }
+
+LTTNG_HIDDEN
+size_t lttng_dynamic_buffer_get_capacity_left(
+               struct lttng_dynamic_buffer *buffer)
+{
+       if (!buffer) {
+               return 0;
+       }
+       return buffer->_capacity - buffer->size;
+}