#include "ipc_msg.h"
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#include <string.h>
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#include <stdlib.h>
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/**
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* @brief 发送目标文件描述符
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* @param fd 传递信息的 UNIX 域 文件描述符
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* @param fd_to_send 待发送的文件描述符
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*/
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int send_fd_args_sendmsg(int fd, int fd_to_send, pid_t pid, void **ppdata, int len)
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{
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struct iovec iov[1];
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struct msghdr msg;
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int control_len = 0;
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int ret = 0;
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memfd_data_st memfd_data;
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struct cmsghdr cm; /* 这是辅助数据头部结构体，文件描述符就是通过这个结构体以及后面的数据部分发送的 */
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control_len = CMSG_SPACE(sizeof(memfd_data_st) + len);
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char * recv_buf = (char *)malloc(control_len);
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if(NULL != recv_buf)
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{
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return -1;
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}
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iov[0].iov_base = recv_buf;
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iov[0].iov_len = 1;
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msg.msg_name = NULL;
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msg.msg_namelen = 0;
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msg.msg_iov = iov;
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msg.msg_iovlen = 1;
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memfd_data.memfd = fd_to_send;
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memfd_data.pid = pid;
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memfd_data.data = *ppdata;
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memfd_data.len = len;
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cm.cmsg_len = control_len; /* 辅助数据的字节数，包扩头部和真正的数据 */
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cm.cmsg_level = SOL_SOCKET; /* 表示原始协议级别，与 setsockopt 的 level 参数相同 */
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cm.cmsg_type = SCM_RIGHTS; /* 控制信息类型，SCM_RIGHTS 表示传送的内容是访问权 */
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*(memfd_data_st*)CMSG_DATA(&cm) = memfd_data;/* 设置真正数据部分为我们想发送的文件描述符 */
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msg.msg_control = &cm; /* 设置辅助数据 */
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msg.msg_controllen = control_len;
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ret = sendmsg(fd, &msg, 0);
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free(recv_buf);
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return ret;
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}
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/**
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* @brief 发送目标文件描述符
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* @param fd 传递信息的 UNIX 域 文件描述符
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* @param fd_to_send 待发送的文件描述符
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*/
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int send_fd_sendmsg(int fd, memfd_data_st** ppmemfd_data)
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{
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memfd_data_st *ptr_memfd_data = *ppmemfd_data;
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return send_fd_args_sendmsg(fd, ptr_memfd_data->memfd, ptr_memfd_data->pid, &ptr_memfd_data->data, ptr_memfd_data->len);
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}
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/**
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* @brief 接受文件描述符
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* @param fd 传递信息的 UNIX 域 文件描述符
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*/
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int recv_fd_recvmsg(int fd, memfd_data_st** ppmemfd_data)
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{
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struct iovec iov[1];
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struct msghdr msg;
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char recv_buf[MAX_LEN];
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int ret = -1;
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int control_len = 0;
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struct cmsghdr cm;
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iov[0].iov_base = recv_buf;
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iov[0].iov_len = 1;
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msg.msg_name = NULL;
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msg.msg_namelen = 0;
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msg.msg_iov = iov;
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msg.msg_iovlen = 1;
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control_len = CMSG_SPACE(sizeof(memfd_data_st) + MAX_LEN);
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msg.msg_control = &cm;
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msg.msg_controllen = control_len;
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ret = recvmsg(fd, &msg, 0);
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if(ret < 0)
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{
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ret = -1;
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}
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int off = offsetof(memfd_data_st, len);
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int len = *(int*)((char *)CMSG_DATA(&cm) + off);
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control_len = CMSG_SPACE(sizeof(memfd_data_st) + len);
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*ppmemfd_data = (memfd_data_st *)malloc(control_len);
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if(*ppmemfd_data == NULL)
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{
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return -1;
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}
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memset(*ppmemfd_data, 0, control_len);
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memcpy(*ppmemfd_data, CMSG_DATA(&cm), control_len);
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return ret;
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}
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