tests/qemu-iotests/socket_scm_helper.c

   1 /*
   2  * SCM_RIGHTS with unix socket help program for test
   3  *
   4  * Copyright IBM, Inc. 2013
   5  *
   6  * Authors:
   7  *  Wenchao Xia    <xiawenc@linux.vnet.ibm.com>
   8  *
   9  * This work is licensed under the terms of the GNU LGPL, version 2 or later.
  10  * See the COPYING.LIB file in the top-level directory.
  11  */
  12
  13 #include <stdio.h>
  14 #include <errno.h>
  15 #include <sys/socket.h>
  16 #include <sys/un.h>
  17 #include <stdlib.h>
  18 #include <sys/types.h>
  19 #include <sys/stat.h>
  20 #include <fcntl.h>
  21 #include <unistd.h>
  22
  23 /* #define SOCKET_SCM_DEBUG */
  24
  25 /*
  26  * @fd and @fd_to_send will not be checked for validation in this function,
  27  * a blank will be sent as iov data to notify qemu.
  28  */
  29 static int send_fd(int fd, int fd_to_send)
  30 {
  31     struct msghdr msg;
  32     struct iovec iov[1];
  33     int ret;
  34     char control[CMSG_SPACE(sizeof(int))];
  35     struct cmsghdr *cmsg;
  36
  37     memset(&msg, 0, sizeof(msg));
  38     memset(control, 0, sizeof(control));
  39
  40     /* Send a blank to notify qemu */
  41     iov[0].iov_base = (void *)" ";
  42     iov[0].iov_len = 1;
  43
  44     msg.msg_iov = iov;
  45     msg.msg_iovlen = 1;
  46
  47     msg.msg_control = control;
  48     msg.msg_controllen = sizeof(control);
  49
  50     cmsg = CMSG_FIRSTHDR(&msg);
  51
  52     cmsg->cmsg_len = CMSG_LEN(sizeof(int));
  53     cmsg->cmsg_level = SOL_SOCKET;
  54     cmsg->cmsg_type = SCM_RIGHTS;
  55     memcpy(CMSG_DATA(cmsg), &fd_to_send, sizeof(int));
  56
  57     do {
  58         ret = sendmsg(fd, &msg, 0);
  59     } while (ret < 0 && errno == EINTR);
  60
  61     if (ret < 0) {
  62         fprintf(stderr, "Failed to send msg, reason: %s\n", strerror(errno));
  63     }
  64
  65     return ret;
  66 }
  67
  68 /* Convert string to fd number. */
  69 static int get_fd_num(const char *fd_str)
  70 {
  71     int sock;
  72     char *err;
  73
  74     errno = 0;
  75     sock = strtol(fd_str, &err, 10);
  76     if (errno) {
  77         fprintf(stderr, "Failed in strtol for socket fd, reason: %s\n",
  78                 strerror(errno));
  79         return -1;
  80     }
  81     if (!*fd_str || *err || sock < 0) {
  82         fprintf(stderr, "bad numerical value for socket fd '%s'\n", fd_str);
  83         return -1;
  84     }
  85
  86     return sock;
  87 }
  88
  89 /*
  90  * To make things simple, the caller needs to specify:
  91  * 1. socket fd.
  92  * 2. path of the file to be sent.
  93  */
  94 int main(int argc, char **argv, char **envp)
  95 {
  96     int sock, fd, ret;
  97
  98 #ifdef SOCKET_SCM_DEBUG
  99     int i;
 100     for (i = 0; i < argc; i++) {
 101         fprintf(stderr, "Parameter %d: %s\n", i, argv[i]);
 102     }
 103 #endif
 104
 105     if (argc != 3) {
 106         fprintf(stderr,
 107                 "Usage: %s < socket-fd > < file-path >\n",
 108                 argv[0]);
 109         return EXIT_FAILURE;
 110     }
 111
 112
 113     sock = get_fd_num(argv[1]);
 114     if (sock < 0) {
 115         return EXIT_FAILURE;
 116     }
 117
 118     /* Now only open a file in readonly mode for test purpose. If more precise
 119        control is needed, use python script in file operation, which is
 120        supposed to fork and exec this program. */
 121     fd = open(argv[2], O_RDONLY);
 122     if (fd < 0) {
 123         fprintf(stderr, "Failed to open file '%s'\n", argv[2]);
 124         return EXIT_FAILURE;
 125     }
 126
 127     ret = send_fd(sock, fd);
 128     if (ret < 0) {
 129         close(fd);
 130         return EXIT_FAILURE;
 131     }
 132
 133     close(fd);
 134     return EXIT_SUCCESS;
 135 }