From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:46134) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UKtMm-0000pS-SO for qemu-devel@nongnu.org; Wed, 27 Mar 2013 12:38:26 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1UKtLG-0002vl-9c for qemu-devel@nongnu.org; Wed, 27 Mar 2013 12:36:57 -0400 Received: from mail-ea0-x235.google.com ([2a00:1450:4013:c01::235]:63836) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1UKtLG-0002vR-16 for qemu-devel@nongnu.org; Wed, 27 Mar 2013 12:36:50 -0400 Received: by mail-ea0-f181.google.com with SMTP id z10so3421849ead.26 for ; Wed, 27 Mar 2013 09:36:49 -0700 (PDT) Sender: Paolo Bonzini From: Paolo Bonzini Date: Wed, 27 Mar 2013 17:36:32 +0100 Message-Id: <1364402192-18169-7-git-send-email-pbonzini@redhat.com> In-Reply-To: <1364402192-18169-1-git-send-email-pbonzini@redhat.com> References: <1364402192-18169-1-git-send-email-pbonzini@redhat.com> Subject: [Qemu-devel] [PATCH 6/6] qemu-file: do not use stdio for qemu_fdopen List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: owasserm@redhat.com, quintela@redhat.com This uses system calls directly for Unix file descriptors, so that the efficient writev_buffer can be used. Pay attention to the possibility of partial writes in writev. Signed-off-by: Paolo Bonzini --- savevm.c | 100 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++------- 1 file changed, 89 insertions(+), 11 deletions(-) diff --git a/savevm.c b/savevm.c index 0415830..8eb5aab 100644 --- a/savevm.c +++ b/savevm.c @@ -356,9 +356,93 @@ static const QEMUFileOps stdio_file_write_ops = { .close = stdio_fclose }; +static ssize_t unix_writev_buffer(void *opaque, struct iovec *iov, int iovcnt) +{ + QEMUFileSocket *s = opaque; + ssize_t len, offset; + ssize_t size = iov_size(iov, iovcnt); + ssize_t total = 0; + + assert(iovcnt > 0); + offset = 0; + while (size > 0) { + /* Find the next start position; skip all full-sized vector elements */ + while (offset >= iov[0].iov_len) { + offset -= iov[0].iov_len; + iov++, iovcnt--; + } + + /* skip `offset' bytes from the (now) first element, undo it on exit */ + assert(iovcnt > 0); + iov[0].iov_base += offset; + iov[0].iov_len -= offset; + + do { + len = writev(s->fd, iov, iovcnt); + } while (len == -1 && errno == EINTR); + if (len == -1) { + return -errno; + } + + /* Undo the changes above */ + iov[0].iov_base -= offset; + iov[0].iov_len += offset; + + /* Prepare for the next iteration */ + offset += len; + total += len; + size -= len; + } + + return total; +} + +static int unix_get_buffer(void *opaque, uint8_t *buf, int64_t pos, int size) +{ + QEMUFileSocket *s = opaque; + ssize_t len; + + for (;;) { + len = read(s->fd, buf, size); + if (len != -1) { + break; + } + if (errno == EAGAIN) { + yield_until_fd_readable(s->fd); + } else if (errno != EINTR) { + break; + } + } + + if (len == -1) { + len = -errno; + } + return len; +} + +static int unix_close(void *opaque) +{ + QEMUFileSocket *s = opaque; + close(s->fd); + g_free(s); + return 0; +} + +static const QEMUFileOps unix_read_ops = { + .get_fd = socket_get_fd, + .get_buffer = unix_get_buffer, + .close = unix_close +}; + +static const QEMUFileOps unix_write_ops = { + .get_fd = socket_get_fd, + .writev_buffer = unix_writev_buffer, + .close = unix_close +}; + QEMUFile *qemu_fdopen(int fd, const char *mode) { - QEMUFileStdio *s; + QEMUFileSocket *s; if (mode == NULL || (mode[0] != 'r' && mode[0] != 'w') || @@ -367,21 +451,15 @@ QEMUFile *qemu_fdopen(int fd, const char *mode) return NULL; } - s = g_malloc0(sizeof(QEMUFileStdio)); - s->stdio_file = fdopen(fd, mode); - if (!s->stdio_file) - goto fail; + s = g_malloc0(sizeof(QEMUFileSocket)); + s->fd = fd; if(mode[0] == 'r') { - s->file = qemu_fopen_ops(s, &stdio_file_read_ops); + s->file = qemu_fopen_ops(s, &unix_read_ops); } else { - s->file = qemu_fopen_ops(s, &stdio_file_write_ops); + s->file = qemu_fopen_ops(s, &unix_write_ops); } return s->file; - -fail: - g_free(s); - return NULL; } static const QEMUFileOps socket_read_ops = { -- 1.8.1.4