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#include <stdio.h>
#include <stdlib.h>
#include <getopt.h>
#include <errno.h>
#include <xf86drm.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <assert.h>
#include <stdbool.h>
#define DRM_HACK_SOCKET_NAME "xorg_drm_master_util"
int recv_fd(int sock)
{
// This function does the arcane magic recving
// file descriptors over unix domain sockets
struct msghdr msg;
struct iovec iov[1];
struct cmsghdr *cmsg = NULL;
char ctrl_buf[CMSG_SPACE(sizeof(int))];
char data[1];
memset(&msg, 0, sizeof(struct msghdr));
memset(ctrl_buf, 0, CMSG_SPACE(sizeof(int)));
iov[0].iov_base = data;
iov[0].iov_len = sizeof(data);
msg.msg_name = NULL;
msg.msg_namelen = 0;
msg.msg_control = ctrl_buf;
msg.msg_controllen = CMSG_SPACE(sizeof(int));
msg.msg_iov = iov;
msg.msg_iovlen = 1;
recvmsg(sock, &msg, 0);
cmsg = CMSG_FIRSTHDR(&msg);
return *((int *) CMSG_DATA(cmsg));
}
void usage(const char *name)
{
printf("usage: %s\n", name);
printf("\n"
"-h, --help: print this help\n"
"-s, --set: drmSetMaster\n"
"-d, --drop: drmDropMaster\n"
"-t, --test: test\n"
"-r, --root: ensure i'm root\n"
"\n");
}
void check_error(char *prog, int err)
{
if (err) {
fprintf(stderr, "%s: %s\n", prog, strerror(errno));
exit(err);
}
}
enum action {HELP, SET, DROP, TEST};
int main(int argc, char *argv[])
{
enum action act = HELP;
int opt, optindex = 0;
int ret = 0;
bool ensure_root = false;
static struct option longopts[] = {
{"help", 0, 0, 'h'},
{"set", 0, 0, 's'},
{"drop", 0, 0, 'd'},
{"test", 0, 0, 't'},
{"root", 0, 0, 'r'},
{0, 0, 0, 0}
};
if (argv[1] == NULL) {
usage(argv[0]);
exit(0);
}
while ((opt = getopt_long(argc, argv, "hsdtr",
longopts, &optindex)) != EOF) {
switch (opt) {
case 's': act = SET; break;
case 'd': act = DROP; break;
case 't': act = TEST; break;
case 'r': ensure_root = true; break;
}
}
if (optind < argc) {
fprintf(stderr, "Error: extra parameter found.\n");
exit(1);
}
if (ensure_root) {
uid_t uid = getuid();
uid_t euid = geteuid();
assert(euid == 0);
ret = setuid(euid);
check_error("setuid", ret);
uid = getuid();
euid = getuid();
assert(uid == 0);
}
if (act == HELP) {
usage(argv[0]);
exit(0);
}
struct sockaddr_un addr;
int sock;
// Create and connect a unix domain socket
sock = socket(AF_UNIX, SOCK_STREAM, 0);
memset(&addr, 0, sizeof(addr));
addr.sun_family = AF_UNIX;
strcpy(&addr.sun_path[1], DRM_HACK_SOCKET_NAME);
connect(sock, (struct sockaddr *)&addr, sizeof(addr));
int fd = recv_fd(sock);
close(sock);
assert(fd != 0);
if (act == SET) {
ret = drmSetMaster(fd);
check_error("drmSetMaster", ret);
} else if (act == DROP) {
ret = drmDropMaster(fd);
check_error("drmDropMaster", ret);
} else if (act == TEST) {
printf("received fd: %d\n", fd);
dprintf(fd, "drm_master_util: writing to received fd ;)\n");
}
return 0;
}
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