/*  $NetBSD: perfused.c,v 1.7 2010/09/07 02:11:04 manu Exp $ */

/*-
 *  Copyright (c) 2010 Emmanuel Dreyfus. All rights reserved.
 * 
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions
 *  are met:
 *  1. Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *  2. Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 * 
 *  THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 *  ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 *  TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 *  PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 *  BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 *  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 *  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 *  POSSIBILITY OF SUCH DAMAGE.
 */ 

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <syslog.h>
#include <ctype.h>
#include <paths.h>
#include <stdarg.h>
#include <err.h>
#include <errno.h>
#include <string.h>
#include <sysexits.h>
#include <signal.h>
#include <puffs.h>
#include <sys/wait.h>
#include <sys/param.h>
#include <sys/queue.h>
#include <sys/uio.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <machine/vmparam.h>

#include "../../lib/libperfuse/perfuse_if.h"
#include "perfused.h"

static int getpeerid(int, pid_t *, uid_t *, gid_t *);
static int access_mount(const char *, uid_t, int);
static void new_mount(int, int);
static int parse_debug(char *);
static void siginfo_handler(int);
static int parse_options(int, char **);
static void get_mount_info(int, struct perfuse_mount_info *);
int main(int, char **);

/*
 * Flags for new_mount()
 */
#define  PMNT_DEVFUSE	0x0	/* We use /dev/fuse */
#define  PMNT_SOCKPAIR	0x1	/* We use socketpair */


static int
getpeerid(s, pidp, uidp, gidp)
	int s;
	pid_t *pidp;
	uid_t *uidp;
	gid_t *gidp;
{
	struct unpcbid unp;
	socklen_t len;
	int error;

	len = sizeof(unp);
	error = getsockopt(s, 0, LOCAL_PEEREID, &unp, &len);
	if (error != 0)
		return error;
		
	if (pidp != NULL)
		*pidp = unp.unp_pid;

	if (uidp != NULL)
		*uidp = unp.unp_euid;

	if (gidp != NULL)
		*gidp = unp.unp_egid;

	return 0;
}

static int
access_mount(mnt, uid, ro)
	const char *mnt;
	uid_t uid;
	int ro;
{
	struct stat st;
	mode_t mode;

	if (uid == 0)
		return 0;

	if (stat(mnt, &st) == -1)
		return -1;
	
	if (st.st_uid != uid)
		return -1;

	mode = S_IRUSR;
	if (!ro)
		mode |= S_IWUSR;
	
	if ((st.st_mode & mode) == mode)
		return 0;

	return -1;
}

static void
get_mount_info(fd, pmi)
	int fd;
	struct perfuse_mount_info *pmi;
{
	struct perfuse_mount_out *pmo;
	char *source = NULL;
	char *target = NULL;
	char *filesystemtype = NULL;
	long mountflags = 0;
	void *data;
	size_t len;

	pmo = (struct perfuse_mount_out *)perfuse_recv_early(fd, sizeof(*pmo));
	if (pmo == NULL) {
		if (shutdown(fd, SHUT_RDWR) != 0)
			DERR(EX_OSERR, "shutdown failed");
		exit(EX_PROTOCOL);
	}

#ifdef PERFUSE_DEBUG
	if (perfuse_diagflags & PDF_MISC)
		DPRINTF("perfuse lengths: source = %"PRId32", "
			"target = %"PRId32", filesystemtype = %"PRId32", "
			"data = %"PRId32"\n", pmo->pmo_source_len, 
			pmo->pmo_target_len, pmo->pmo_filesystemtype_len, 
			pmo->pmo_data_len);
#endif
	len = pmo->pmo_source_len;
	source = perfuse_recv_early(fd, len);

	len = pmo->pmo_target_len;
	target = perfuse_recv_early(fd, len);

	len = pmo->pmo_filesystemtype_len;
	filesystemtype = perfuse_recv_early(fd, len);

	mountflags = pmo->pmo_mountflags;

	len = pmo->pmo_data_len;
	data = perfuse_recv_early(fd, len);

#ifdef PERFUSE_DEBUG
	if (perfuse_diagflags & PDF_MISC)
		DPRINTF("%s(\"%s\", \"%s\", \"%s\", 0x%lx, \"%s\")\n", 
		__func__, source, target, filesystemtype, 
		mountflags, (const char *)data);
#endif
	pmi->pmi_source = source;
	pmi->pmi_target = target;
	pmi->pmi_filesystemtype = filesystemtype;
	pmi->pmi_mountflags = (int)mountflags;
	pmi->pmi_data = data;

	return;
}

static void
new_mount(fd, pmnt_flags)
	int fd;
	int pmnt_flags;
{
	struct puffs_usermount *pu;
	struct perfuse_mount_info pmi;
	struct perfuse_callbacks pc;
	int ro_flag;
	pid_t pid;
	int flags;


	pid = (perfuse_diagflags & PDF_FOREGROUND) ? 0 : fork();
	switch(pid) {
	case -1:
		DERR(EX_OSERR, "cannot fork");
		break;
	case 0:
		break;
	default:
		return;
		/* NOTREACHED */
		break;
	}

	/*
	 * Mount information (source, target, mount flags...)
	 */
	get_mount_info(fd, &pmi);

	/*
	 * Get peer identity. If we use socketpair (-i option),
	 * peer identity if the same as us.
	 */
	if (pmnt_flags & PMNT_SOCKPAIR) {
		pmi.pmi_uid = getuid();
	} else {
		if (getpeerid(fd, NULL, &pmi.pmi_uid, NULL) != 0) {
			DWARNX("Unable to retreive peer identity");
			pmi.pmi_uid = (uid_t)-1;
		}
	}

	/*
	 * Check that peer owns mountpoint and read (and write) on it?
	 */
	ro_flag = pmi.pmi_mountflags & MNT_RDONLY;
	if (access_mount(pmi.pmi_target, pmi.pmi_uid, ro_flag) != 0)
		DERRX(EX_NOPERM, "insuficient privileges to mount on %s", 
		      pmi.pmi_target);


	/*
	 * Initialize libperfuse, which will initialize libpuffs
	 */
	pc.pc_new_msg = perfuse_new_pb;
	pc.pc_xchg_msg = perfuse_xchg_pb;
	pc.pc_destroy_msg = (perfuse_destroy_msg_fn)puffs_framebuf_destroy;
	pc.pc_get_inhdr = perfuse_get_inhdr;
	pc.pc_get_inpayload = perfuse_get_inpayload;
	pc.pc_get_outhdr = perfuse_get_outhdr;
	pc.pc_get_outpayload = perfuse_get_outpayload;

	pu = perfuse_init(&pc, &pmi);
	
	puffs_framev_init(pu, perfuse_readframe, perfuse_writeframe, 
			  perfuse_cmpframe, perfuse_gotframe, perfuse_fdnotify);

	if (puffs_framev_addfd(pu, fd, PUFFS_FBIO_READ|PUFFS_FBIO_WRITE) == -1)
		DERR(EX_SOFTWARE, "puffs_framev_addfd failed");

	perfuse_setspecific(pu, (void *)(long)fd);

	setproctitle("perfused %s", pmi.pmi_target);
	(void)kill(getpid(), SIGINFO);		/* This is for -s option */

	perfuse_fs_init(pu);

	/*
	 * Non blocking I/O on /dev/fuse
	 * This must be done after perfuse_fs_init
	 */
	if ((flags = fcntl(fd, F_GETFL, 0)) == -1)
		DERR(EX_OSERR, "fcntl failed");
	if (fcntl(fd, F_SETFL, flags|O_NONBLOCK) != 0)
		DERR(EX_OSERR, "fcntl failed");

	/*
	 * Hand over control to puffs main loop.
	 */
	(void)perfuse_mainloop(pu);

	DERRX(EX_SOFTWARE, "perfuse_mainloop exit");

	/* NOTREACHED */
	return;
}

static int 
parse_debug(optstr)
	char *optstr;
{
	int retval = PDF_SYSLOG;
	char *opt;
	char *lastp;

	for (opt = strtok_r(optstr, ",", &lastp);
	     opt;
	     opt = strtok_r(NULL, ",", &lastp)) {
		if (strcmp(opt, "fuse") == 0)
			retval |= PDF_FUSE;
		else if (strcmp(opt, "puffs") == 0)
			retval |= PDF_PUFFS;
		else if (strcmp(opt, "dump") == 0)
			retval |= PDF_DUMP;
		else if (strcmp(opt, "fh") == 0)
			retval |= PDF_FH;
		else if (strcmp(opt, "readdir") == 0)
			retval |= PDF_READDIR;
		else if (strcmp(opt, "reclaim") == 0)
			retval |= PDF_RECLAIM;
		else if (strcmp(opt, "requeue") == 0)
			retval |= PDF_REQUEUE;
		else if (strcmp(opt, "sync") == 0)
			retval |= PDF_SYNC;
		else if (strcmp(opt, "misc") == 0)
			retval |= PDF_MISC;
		else
			DERRX(EX_USAGE, "unknown debug flag \"%s\"", opt);
	}

	return retval;
}

/* ARGSUSED0 */
static void
siginfo_handler(sig)
	int sig;
{
	static int old_flags = 0;
	int swap;

	swap = perfuse_diagflags;
	perfuse_diagflags = old_flags;
	old_flags = swap;

	DWARNX("debug %sabled", old_flags == 0 ? "en" : "dis");

	return;
}

static int
parse_options(argc, argv)
	int argc;
	char **argv;
{
	int ch;
	int foreground = 0;
	int retval = -1;

	perfuse_diagflags = PDF_FOREGROUND | PDF_SYSLOG;

	while ((ch = getopt(argc, argv, "d:fsi:")) != -1) {
		switch (ch) {
		case 'd':
			perfuse_diagflags |= parse_debug(optarg);
			break;
		case 's':
			if (signal(SIGINFO, siginfo_handler) != 0)
				DERR(EX_OSERR, "signal failed");
			break;
		case 'f':
			foreground = 1;
			perfuse_diagflags |= PDF_MISC;
			break;
		case 'i':
			retval = atoi(optarg);
			foreground = 1;
			break;
		default:
			DERR(EX_USAGE, "%s [-fs] [-d level] [-i fd]", argv[0]);
			break;
		}
	}
	
	if (!foreground)
		perfuse_diagflags &= ~PDF_FOREGROUND;

	return retval; 
}

int
main(argc, argv)
	int argc;
	char **argv;
{
	int s;

	s = parse_options(argc, argv);

	if (perfuse_diagflags & PDF_SYSLOG)
		openlog("perfused", 0, LOG_DAEMON);

	if (!(perfuse_diagflags & PDF_FOREGROUND))
		if (daemon(0, 0) != 0)
			DERR(EX_OSERR, "daemon failed");

	if (s != -1) {
		new_mount(s, PMNT_SOCKPAIR);
		DERRX(EX_SOFTWARE, "new_mount exit while -i is used");
	}

	s = perfuse_open_sock();
	
	do {
		struct sockaddr *sa;
		struct sockaddr_storage ss;
		socklen_t ss_len;
		int fd;

#ifdef PERFUSE_DEBUG
		if (perfuse_diagflags & PDF_MISC)
			DPRINTF("waiting connexion\n");
#endif
		sa = (struct sockaddr *)(void *)&ss;
		ss_len = sizeof(ss);
		if ((fd = accept(s, sa, &ss_len)) == -1)
			DERR(EX_OSERR,  "accept failed");
#ifdef PERFUSE_DEBUG
		if (perfuse_diagflags & PDF_MISC)
			DPRINTF("connexion accepted\n");
#endif
		new_mount(fd, PMNT_DEVFUSE);
	} while (1 /* CONSTCOND */);
		
	/* NOTREACHED */
	return 0;
}