commit 095e15f8ac8216cd945b85c159b461d8cd0697a3 Author: Nick Mathewson nickm@torproject.org Date: Wed Sep 6 09:30:50 2017 -0400

Add a zero-copy buffer move implementation. --- src/common/buffers.c | 22 ++++++++++++++++++++++ src/common/buffers.h | 1 + 2 files changed, 23 insertions(+)

diff --git a/src/common/buffers.c b/src/common/buffers.c index d7c4e4d8c..d1725cf1a 100644 --- a/src/common/buffers.c +++ b/src/common/buffers.c @@ -838,6 +838,28 @@ buf_move_to_buf(buf_t *buf_out, buf_t *buf_in, size_t *buf_flushlen) return (int)cp; }

+/** Moves all data from <b>buf_in</b> to <b>buf_out</b>, without copying. + */ +void +buf_move_all(buf_t *buf_out, buf_t *buf_in) +{ + tor_assert(buf_out); + if (!buf_in) + return; + + if (buf_out->head == NULL) { + buf_out->head = buf_in->head; + buf_out->tail = buf_in->tail; + } else { + buf_out->tail->next = buf_in->head; + buf_out->tail = buf_in->tail; + } + + buf_out->datalen += buf_in->datalen; + buf_in->head = buf_in->tail = NULL; + buf_in->datalen = 0; +} + /** Internal structure: represents a position in a buffer. */ typedef struct buf_pos_t { const chunk_t *chunk; /**< Which chunk are we pointing to? */ diff --git a/src/common/buffers.h b/src/common/buffers.h index b05c5b13d..56ba7c77b 100644 --- a/src/common/buffers.h +++ b/src/common/buffers.h @@ -51,6 +51,7 @@ void buf_add_vprintf(buf_t *buf, const char *format, va_list args) int buf_add_compress(buf_t *buf, struct tor_compress_state_t *state, const char *data, size_t data_len, int done); int buf_move_to_buf(buf_t *buf_out, buf_t *buf_in, size_t *buf_flushlen); +void buf_move_all(buf_t *buf_out, buf_t *buf_in); void buf_peek(const buf_t *buf, char *string, size_t string_len); void buf_drain(buf_t *buf, size_t n); int buf_get_bytes(buf_t *buf, char *string, size_t string_len);