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author | Ian Jackson <ian.jackson@eu.citrix.com> | 2012-05-11 18:58:58 +0100 |
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committer | Ian Jackson <ian.jackson@eu.citrix.com> | 2012-05-11 18:58:58 +0100 |
commit | a1eaa32119645579188783e0a18939bfeccb4961 (patch) | |
tree | c64ea487ec7c71aff8578c9492c87e1c0774d4b9 /tools/libxl/libxl_utils.c | |
parent | c4dcbee67e6db4f4cf3b871646419bda6660be76 (diff) | |
download | xen-a1eaa32119645579188783e0a18939bfeccb4961.tar.gz xen-a1eaa32119645579188783e0a18939bfeccb4961.tar.bz2 xen-a1eaa32119645579188783e0a18939bfeccb4961.zip |
libxl: Introduce libxl__sendmsg_fds and libxl__recvmsg_fds
Provide functions for sending and receiving fds.
There used to be fd-sending functionality in libxl_qmp.c before
25298:84ae90427c54, which this implementation is partially derived
from.
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Jackson <Ian.Jackson@eu.citrix.com>
Diffstat (limited to 'tools/libxl/libxl_utils.c')
-rw-r--r-- | tools/libxl/libxl_utils.c | 104 |
1 files changed, 104 insertions, 0 deletions
diff --git a/tools/libxl/libxl_utils.c b/tools/libxl/libxl_utils.c index 1a4874ce68..19b4615b16 100644 --- a/tools/libxl/libxl_utils.c +++ b/tools/libxl/libxl_utils.c @@ -579,6 +579,110 @@ 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; + } +} + void libxl_dominfo_list_free(libxl_dominfo *list, int nr) { int i; |