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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH 15/15] libxl: Introduce libxl__sendmsg_fds and libxl__recvmsg_fds
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 <ian.jackson@xxxxxxxxxxxxx>
---
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 <yajl/yajl_gen.h>
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
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