linuxkit/alpine/packages/9pmount-vsock/9pmount-vsock.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <getopt.h>
#include <syslog.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <fcntl.h>
#include <err.h>
#include <sys/wait.h>

#include "hvsock.h"

#define NONE 0
#define LISTEN 1
#define CONNECT 2

int mode = NONE;

char *default_sid = "C378280D-DA14-42C8-A24E-0DE92A1028E2";
char *mount = "/bin/mount";

void fatal(const char *msg)
{
	syslog(LOG_CRIT, "%s Error: %d. %s", msg, errno, strerror(errno));
	exit(1);
}

static int handle(int fd, char *tag, char *path)
{
	char *options = NULL;
	int status;
	pid_t pid;
	int res;

	res = asprintf(&options,
		       "trans=fd,dfltuid=1001,dfltgid=50,version=9p2000,msize=4096,rfdno=%d,wfdno=%d",
		       fd, fd);
	if (res < 0)
		fatal("asprintf()");

	char *argv[] = {
		mount,
		"-t", "9p", "-o", options,
		tag, path,
		NULL
	};

	pid = fork();
	if (pid == 0) {
		execv(mount, argv);
		fatal("execv()");
	}

	res = waitpid(pid, &status, 0);
	if (res == -1) {
		syslog(LOG_CRIT,
		       "waitpid failed: %d. %s", errno, strerror(errno));
		exit(1);
	}
	return WEXITSTATUS(status);
}

static int create_listening_socket(GUID serviceid)
{
	SOCKADDR_HV sa;
	int lsock;
	int res;

	lsock = socket(AF_HYPERV, SOCK_STREAM, HV_PROTOCOL_RAW);
	if (lsock == -1)
		fatal("socket()");

	sa.Family = AF_HYPERV;
	sa.Reserved = 0;
	sa.VmId = HV_GUID_WILDCARD;
	sa.ServiceId = serviceid;

	res = bind(lsock, (const struct sockaddr *)&sa, sizeof(sa));
	if (res == -1)
		fatal("bind()");

	res = listen(lsock, 1);
	if (res == -1)
		fatal("listen()");

	return lsock;
}

static int connect_socket(GUID serviceid)
{
	SOCKADDR_HV sa;
	int sock;
	int res;

	sock = socket(AF_HYPERV, SOCK_STREAM, HV_PROTOCOL_RAW);
	if (sock == -1)
		fatal("socket()");

	sa.Family = AF_HYPERV;
	sa.Reserved = 0;
	sa.VmId = HV_GUID_PARENT;
	sa.ServiceId = serviceid;

	res = connect(sock, (const struct sockaddr *)&sa, sizeof(sa));
	if (res == -1)
		fatal("connect()");

	return sock;
}

static int accept_socket(int lsock)
{
	SOCKADDR_HV sac;
	socklen_t socklen = sizeof(sac);
	int csock;

	csock = accept(lsock, (struct sockaddr *)&sac, &socklen);
	if (csock == -1)
		fatal("accept()");

	syslog(LOG_INFO, "Connect from: " GUID_FMT ":" GUID_FMT "\n",
	       GUID_ARGS(sac.VmId), GUID_ARGS(sac.ServiceId));

	return csock;
}

void usage(char *name)
{
	printf("%s: mount a 9P filesystem from an hvsock connection\n", name);
	printf("usage:\n");
	printf("\t[--serviceid <guid>] <listen | connect> <tag> <path>\n");
	printf("where\n");
	printf("\t--serviceid <guid>: use <guid> as the well-known service GUID\n");
	printf("\t  (defaults to %s)\n", default_sid);
	printf("\t--listen: listen forever for incoming AF_HVSOCK connections\n");
	printf("\t--connect: connect to the parent partition\n");
}

int main(int argc, char **argv)
{
	int res = 0;
	GUID sid;
	int c;
	/* Defaults to a testing GUID */
	char *serviceid = default_sid;
	char *tag = NULL;
	char *path = NULL;

	opterr = 0;
	while (1) {
		static struct option long_options[] = {
			/* These options set a flag. */
			{"serviceid", required_argument, NULL, 's'},
			{0, 0, 0, 0}
		};
		int option_index = 0;

		c = getopt_long(argc, argv, "s:", long_options, &option_index);
		if (c == -1)
			break;

		switch (c) {
		case 's':
			serviceid = optarg;
			break;
		case 0:
			break;
		default:
			usage(argv[0]);
			exit(1);
		}
	}

	if (optind < argc) {
		if (strcmp(argv[optind], "listen") == 0)
			mode = LISTEN;
		else if (strcmp(argv[optind], "connect") == 0)
			mode = CONNECT;
		optind++;
	}
	if (mode == NONE) {
		fprintf(stderr, "Please supply either listen or connect\n");
		usage(argv[0]);
		exit(1);
	}

	if (optind < argc)
		tag = argv[optind++];

	if (optind < argc)
		path = argv[optind++];

	if (!tag) {
		fprintf(stderr, "Please supply a tag name\n");
		usage(argv[0]);
		exit(1);
	}

	if (!path) {
		fprintf(stderr, "Please supply a path\n");
		usage(argv[0]);
		exit(1);
	}

	res = parseguid(serviceid, &sid);
	if (res) {
		fprintf(stderr,
			"Failed to parse serviceid as GUID: %s\n", serviceid);
		usage(argv[0]);
		exit(1);
	}

	openlog(argv[0], LOG_CONS | LOG_NDELAY | LOG_PERROR, LOG_DAEMON);
	for (;;) {
		int lsocket;
		int sock;
		int r;

		if (mode == LISTEN) {
			syslog(LOG_INFO, "starting in listening mode with serviceid=%s, tag=%s, path=%s", serviceid, tag, path);
			lsocket = create_listening_socket(sid);
			sock = accept_socket(lsocket);
			close(lsocket);
		} else {
			syslog(LOG_INFO, "starting in connect mode with serviceid=%s, tag=%s, path=%s", serviceid, tag, path);
			sock = connect_socket(sid);
		}

		r = handle(sock, tag, path);
		close(sock);

		if (r == 0) {
			syslog(LOG_INFO, "mount successful for serviceid=%s tag=%s path=%s", serviceid, tag, path);
			exit(0);
		}

		/*
		 * This can happen if the client times out the connection
		 * after we accept it
		 */
		syslog(LOG_CRIT, "mount failed with %d for serviceid=%s tag=%s path=%s", r, serviceid, tag, path);
		sleep(1); /* retry */
	}
}