From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ian Jackson Subject: [PATCH 15/15] libxl: Introduce libxl__sendmsg_fds and libxl__recvmsg_fds Date: Fri, 24 Feb 2012 18:55:03 +0000 Message-ID: <1330109703-6536-16-git-send-email-ian.jackson@eu.citrix.com> References: <1330109703-6536-1-git-send-email-ian.jackson@eu.citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1330109703-6536-1-git-send-email-ian.jackson@eu.citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: xen-devel@lists.xensource.com Cc: Ian Jackson List-Id: xen-devel@lists.xenproject.org We will want to reuse the fd-sending code, so break it out into its own function, and provide the corresponding sending function. Signed-off-by: Ian Jackson --- tools/libxl/libxl_internal.h | 11 ++++ tools/libxl/libxl_qmp.c | 31 ++----------- tools/libxl/libxl_utils.c | 104 ++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 119 insertions(+), 27 deletions(-) diff --git a/tools/libxl/libxl_internal.h b/tools/libxl/libxl_internal.h index 09bfd27..1762bf8 100644 --- a/tools/libxl/libxl_internal.h +++ b/tools/libxl/libxl_internal.h @@ -1083,6 +1083,17 @@ _hidden void libxl__qmp_cleanup(libxl__gc *gc, uint32_t domid); _hidden int libxl__qmp_initializations(libxl__gc *gc, uint32_t domid, const libxl_domain_config *guest_config); +/* on failure, logs */ +int libxl__sendmsg_fds(libxl__gc *gc, int carrier, + const void *data, size_t datalen, + int nfds, const int fds[], const char *what); + +/* Insists on receiving exactly nfds and datalen. On failure, logs + * and leaves *fds untouched. */ +int libxl__recvmsg_fds(libxl__gc *gc, int carrier, + void *databuf, size_t datalen, + int nfds, int fds[], const char *what); + /* from libxl_json */ #include diff --git a/tools/libxl/libxl_qmp.c b/tools/libxl/libxl_qmp.c index 43fd134..e346e05 100644 --- a/tools/libxl/libxl_qmp.c +++ b/tools/libxl/libxl_qmp.c @@ -544,38 +544,15 @@ static int qmp_send_fd(libxl__gc *gc, libxl__qmp_handler *qmp, qmp_request_context *context, int fd) { - struct msghdr msg = { 0 }; - struct cmsghdr *cmsg; - char control[CMSG_SPACE(sizeof (fd))]; - struct iovec iov; char *buf = NULL; + int rc; buf = qmp_send_prepare(gc, qmp, "getfd", args, callback, opaque, context); - /* Response data */ - iov.iov_base = buf; - iov.iov_len = strlen(buf); - - /* compose the message */ - msg.msg_iov = &iov; - msg.msg_iovlen = 1; - msg.msg_control = control; - msg.msg_controllen = sizeof (control); - - /* attach open fd */ - cmsg = CMSG_FIRSTHDR(&msg); - cmsg->cmsg_level = SOL_SOCKET; - cmsg->cmsg_type = SCM_RIGHTS; - cmsg->cmsg_len = CMSG_LEN(sizeof (fd)); - *(int *)CMSG_DATA(cmsg) = fd; - - msg.msg_controllen = cmsg->cmsg_len; + rc = libxl__sendmsg_fds(gc, qmp->qmp_fd, buf, strlen(buf), 1, &fd, + "QMP message to QEMU"); + if (rc) return rc; - if (sendmsg(qmp->qmp_fd, &msg, 0) < 0) { - LIBXL__LOG_ERRNO(qmp->ctx, LIBXL__LOG_ERROR, - "Failed to send a QMP message to QEMU."); - return ERROR_FAIL; - } if (libxl_write_exactly(qmp->ctx, qmp->qmp_fd, "\r\n", 2, "CRLF", "QMP socket")) { return ERROR_FAIL; diff --git a/tools/libxl/libxl_utils.c b/tools/libxl/libxl_utils.c index 9f9f91d..d2efa5c 100644 --- a/tools/libxl/libxl_utils.c +++ b/tools/libxl/libxl_utils.c @@ -534,6 +534,110 @@ void libxl_cputopology_list_free(libxl_cputopology *list, int nr) free(list); } +int libxl__sendmsg_fds(libxl__gc *gc, int carrier, + const void *data, size_t datalen, + int nfds, const int fds[], const char *what) { + struct msghdr msg = { 0 }; + struct cmsghdr *cmsg; + size_t spaceneeded = nfds * sizeof(fds[0]); + char control[CMSG_SPACE(spaceneeded)]; + struct iovec iov; + int r; + + iov.iov_base = (void*)data; + iov.iov_len = datalen; + + /* compose the message */ + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = control; + msg.msg_controllen = sizeof(control); + + /* attach open fd */ + cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + cmsg->cmsg_len = CMSG_LEN(spaceneeded); + memcpy(CMSG_DATA(cmsg), fds, spaceneeded); + + msg.msg_controllen = cmsg->cmsg_len; + + r = sendmsg(carrier, &msg, 0); + if (r < 0) { + LOGE(ERROR, "failed to send fd-carrying message (%s)", what); + return ERROR_FAIL; + } + + return 0; +} + +int libxl__recvmsg_fds(libxl__gc *gc, int carrier, + void *databuf, size_t datalen, + int nfds, int fds[], const char *what) +{ + struct msghdr msg = { 0 }; + struct cmsghdr *cmsg; + size_t spaceneeded = nfds * sizeof(fds[0]); + char control[CMSG_SPACE(spaceneeded)]; + struct iovec iov; + int r; + + iov.iov_base = databuf; + iov.iov_len = datalen; + + msg.msg_iov = &iov; + msg.msg_iovlen = 1; + msg.msg_control = control; + msg.msg_controllen = sizeof(control); + + for (;;) { + r = recvmsg(carrier, &msg, 0); + if (r < 0) { + if (errno == EINTR) continue; + if (errno == EWOULDBLOCK) return -1; + LOGE(ERROR,"recvmsg failed (%s)", what); + return ERROR_FAIL; + } + if (r == 0) { + LOG(ERROR,"recvmsg got EOF (%s)", what); + return ERROR_FAIL; + } + cmsg = CMSG_FIRSTHDR(&msg); + if (cmsg->cmsg_len <= CMSG_LEN(0)) { + LOG(ERROR,"recvmsg got no control msg" + " when expecting fds (%s)", what); + return ERROR_FAIL; + } + if (cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS) { + LOG(ERROR, "recvmsg got unexpected" + " cmsg_level %d (!=%d) or _type %d (!=%d) (%s)", + cmsg->cmsg_level, SOL_SOCKET, + cmsg->cmsg_type, SCM_RIGHTS, + what); + return ERROR_FAIL; + } + if (cmsg->cmsg_len != CMSG_LEN(spaceneeded) || + msg.msg_controllen != cmsg->cmsg_len) { + LOG(ERROR, "recvmsg got unexpected" + " number of fds or extra control data" + " (%ld bytes' worth, expected %ld) (%s)", + (long)CMSG_LEN(spaceneeded), (long)cmsg->cmsg_len, + what); + int i, fd; + unsigned char *p; + for (i=0, p=CMSG_DATA(cmsg); + CMSG_SPACE(i * sizeof(fds[0])); + i++, i+=sizeof(fd)) { + memcpy(&fd, p, sizeof(fd)); + close(fd); + } + return ERROR_FAIL; + } + memcpy(fds, CMSG_DATA(cmsg), spaceneeded); + return 0; + } +} + /* * Local variables: * mode: C -- 1.7.2.5