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/*
* SCM_RIGHTS with unix socket help program for test
*
* Copyright IBM, Inc. 2013
*
* Authors:
* Wenchao Xia <xiawenc@linux.vnet.ibm.com>
*
* This work is licensed under the terms of the GNU LGPL, version 2 or later.
* See the COPYING.LIB file in the top-level directory.
*/
#include <stdio.h>
#include <errno.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
/* #define SOCKET_SCM_DEBUG */
/*
* @fd and @fd_to_send will not be checked for validation in this function,
* a blank will be sent as iov data to notify qemu.
*/
static int send_fd(int fd, int fd_to_send)
{
struct msghdr msg;
struct iovec iov[1];
int ret;
char control[CMSG_SPACE(sizeof(int))];
struct cmsghdr *cmsg;
memset(&msg, 0, sizeof(msg));
memset(control, 0, sizeof(control));
/* Send a blank to notify qemu */
iov[0].iov_base = (void *)" ";
iov[0].iov_len = 1;
msg.msg_iov = iov;
msg.msg_iovlen = 1;
msg.msg_control = control;
msg.msg_controllen = sizeof(control);
cmsg = CMSG_FIRSTHDR(&msg);
cmsg->cmsg_len = CMSG_LEN(sizeof(int));
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
memcpy(CMSG_DATA(cmsg), &fd_to_send, sizeof(int));
do {
ret = sendmsg(fd, &msg, 0);
} while (ret < 0 && errno == EINTR);
if (ret < 0) {
fprintf(stderr, "Failed to send msg, reason: %s\n", strerror(errno));
}
return ret;
}
/* Convert string to fd number. */
static int get_fd_num(const char *fd_str)
{
int sock;
char *err;
errno = 0;
sock = strtol(fd_str, &err, 10);
if (errno) {
fprintf(stderr, "Failed in strtol for socket fd, reason: %s\n",
strerror(errno));
return -1;
}
if (!*fd_str || *err || sock < 0) {
fprintf(stderr, "bad numerical value for socket fd '%s'\n", fd_str);
return -1;
}
return sock;
}
/*
* To make things simple, the caller needs to specify:
* 1. socket fd.
* 2. path of the file to be sent.
*/
int main(int argc, char **argv, char **envp)
{
int sock, fd, ret;
#ifdef SOCKET_SCM_DEBUG
int i;
for (i = 0; i < argc; i++) {
fprintf(stderr, "Parameter %d: %s\n", i, argv[i]);
}
#endif
if (argc != 3) {
fprintf(stderr,
"Usage: %s < socket-fd > < file-path >\n",
argv[0]);
return EXIT_FAILURE;
}
sock = get_fd_num(argv[1]);
if (sock < 0) {
return EXIT_FAILURE;
}
/* Now only open a file in readonly mode for test purpose. If more precise
control is needed, use python script in file operation, which is
supposed to fork and exec this program. */
fd = open(argv[2], O_RDONLY);
if (fd < 0) {
fprintf(stderr, "Failed to open file '%s'\n", argv[2]);
return EXIT_FAILURE;
}
ret = send_fd(sock, fd);
if (ret < 0) {
close(fd);
return EXIT_FAILURE;
}
close(fd);
return EXIT_SUCCESS;
}
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