This patch adds recv_pipefd() to receive the pipe file descriptor that passed by source process.
Signed-off-by: Lei Li <li...@linux.vnet.ibm.com> --- migration-local.c | 64 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 64 insertions(+), 0 deletions(-) diff --git a/migration-local.c b/migration-local.c index f2871d8..ed0ae6c 100644 --- a/migration-local.c +++ b/migration-local.c @@ -218,3 +218,67 @@ static int send_pipefd(int sockfd, int pipefd) return ret; } + +/* + * Receive a pipe file descriptor from a source process + * via unix socket. + * + * Return negative value if there has been an recvmsg error or + * no fd to be received. Return 0 if the connection closed by + * source. Return file descriptor on success. + * + */ +static int recv_pipefd(int sockfd) +{ + struct msghdr msg; + struct iovec iov[1]; + ssize_t n; + int pipefd = -1; + char req[1]; + + union { + struct cmsghdr cm; + char control[CMSG_SPACE(sizeof(int))]; + } control_un; + struct cmsghdr *cmptr; + + msg.msg_control = control_un.control; + msg.msg_controllen = sizeof(control_un.control); + + msg.msg_name = NULL; + msg.msg_namelen = 0; + + iov[0].iov_base = req; + iov[0].iov_len = sizeof(req); + msg.msg_iov = iov; + msg.msg_iovlen = 1; + + if ( (n = recvmsg(sockfd, &msg, 0)) <= 0) { + fprintf(stderr, "recvmsg error: %s\n", strerror(errno)); + return n; + } + + /* req 0x01 means there is a file descriptor to receive */ + if (req[0] != 0x01) { + return pipefd; + } + + if ( (cmptr = CMSG_FIRSTHDR(&msg)) != NULL && + cmptr->cmsg_len == CMSG_LEN(sizeof(int))) { + if (cmptr->cmsg_level != SOL_SOCKET) { + DPRINTF(stderr, "control level != SOL_SOCKET\n"); + return pipefd; + } else if (cmptr->cmsg_type != SCM_RIGHTS) { + DPRINTF(stderr, "control type != SCM_RIGHTS\n"); + return pipefd; + } + /* The pipe file descriptor to be received */ + pipefd = *((int *) CMSG_DATA(cmptr)); + DPRINTF("pipefd received successfully: %d\n", pipefd); + } else { + /* Descriptor was not passed */ + DPRINTF(stderr, "pipefd was not passed\n"); + } + + return pipefd; +} -- 1.7.7.6