#include <stddef.h>
#include <stdint.h>
+#include <common/macros.h>
struct lttng_dynamic_buffer {
char *data;
+ /* size is the buffer's currently used capacity. */
size_t size;
- size_t capacity;
+ /*
+ * capacity shall not be accessed by users directly, it is meant for
+ * internal use only.
+ */
+ size_t _capacity;
};
+/*
+ * Initialize a dynamic buffer. This performs no allocation and is meant
+ * to be used instead of memset or explicit initialization of the buffer.
+ */
+LTTNG_HIDDEN
void lttng_dynamic_buffer_init(struct lttng_dynamic_buffer *buffer);
+/*
+ * Append the content of a raw memory buffer to the end of a dynamic buffer
+ * (after its current "size"). The dynamic buffer's size is increased by
+ * "len", and its capacity is adjusted automatically.
+ */
+LTTNG_HIDDEN
int lttng_dynamic_buffer_append(struct lttng_dynamic_buffer *buffer,
const void *buf, size_t len);
+/*
+ * Performs the same action as lttng_dynamic_buffer_append(), but using another
+ * dynamic buffer as the source buffer. The source buffer's size is used in lieu
+ * of "len".
+ */
+LTTNG_HIDDEN
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_.
+ * a size increase 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.
+ * after will zero-out the result of the operation.
+ *
+ * Shrinking a buffer does not zero the old content. If the buffer may contain
+ * sensititve information, it must be cleared manually _before_ changing the
+ * size.
+ *
+ * NOTE: It is striclty _invalid_ to access memory after _size_, regardless
+ * of prior calls to set_capacity().
*/
+LTTNG_HIDDEN
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.
+ * as necessary. The buffer's content is preserved. Setting a buffer's capacity
+ * is meant as a _hint_ to the underlying buffer and is only optimization; no
+ * guarantee is offered that subsequent calls to append or set_size will succeed.
*
* If the current size > new_capacity, the operation will fail.
*/
+LTTNG_HIDDEN
int lttng_dynamic_buffer_set_capacity(struct lttng_dynamic_buffer *buffer,
size_t new_capacity);
/* Release any memory used by the dynamic buffer. */
+LTTNG_HIDDEN
void lttng_dynamic_buffer_reset(struct lttng_dynamic_buffer *buffer);
+/* Get the space left in the buffer before a new resize is needed. */
+LTTNG_HIDDEN
+size_t lttng_dynamic_buffer_get_capacity_left(
+ struct lttng_dynamic_buffer *buffer);
+
#endif /* LTTNG_DYNAMIC_BUFFER_H */