diff --git a/util/iov.c b/util/iov.c index adb9a70fcd..110d18eba6 100644 --- a/util/iov.c +++ b/util/iov.c @@ -145,7 +145,9 @@ ssize_t iov_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt, bool do_send) { ssize_t ret; + size_t orig_len, tail; unsigned si, ei; /* start and end indexes */ + if (bytes == 0) { /* Catch the do-nothing case early, as otherwise we will pass an * empty iovec to sendmsg/recvmsg(), and not all implementations @@ -174,31 +176,29 @@ ssize_t iov_send_recv(int sockfd, struct iovec *iov, unsigned iov_cnt, } /* Find the end position skipping `bytes' bytes: */ /* first, skip all full-sized elements */ - for (ei = 0; ei < iov_cnt && iov[ei].iov_len <= bytes; ++ei) { - bytes -= iov[ei].iov_len; + tail = bytes; + for (ei = 0; ei < iov_cnt && iov[ei].iov_len <= tail; ++ei) { + tail -= iov[ei].iov_len; } - if (bytes) { - /* second, fixup the last element, and remember - * the length we've cut from the end of it in `bytes' */ - size_t tail; + if (tail) { + /* second, fixup the last element, and remember the original + * length */ assert(ei < iov_cnt); - assert(iov[ei].iov_len > bytes); - tail = iov[ei].iov_len - bytes; - iov[ei].iov_len = bytes; - bytes = tail; /* bytes is now equal to the tail size */ - ++ei; + assert(iov[ei].iov_len > tail); + orig_len = iov[ei].iov_len; + iov[ei++].iov_len = tail; } ret = do_send_recv(sockfd, iov, ei, do_send); /* Undo the changes above */ + if (tail) { + iov[ei-1].iov_len = orig_len; + } if (offset) { iov[0].iov_base -= offset; iov[0].iov_len += offset; } - if (bytes) { - iov[ei-1].iov_len += bytes; - } return ret; }