/*  $NetBSD: perfused.c,v 1.26 2021/08/08 20:56:54 nia 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 "perfused.h"

/*
* This is used for trace file. of course it will not work if
* we ever mount multiple filesystems in a single perfused,
* but it is not sure we will ever want to do that.
*/
static struct puffs_usermount *perfused_mount = NULL;
static FILE *perfused_trace = NULL;

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 void sigusr1_handler(int);
static int parse_options(int, char **);
static void get_mount_info(int, struct perfuse_mount_info *, int);

/*
* Flags for new_mount()
*/
#define  PMNT_DEVFUSE   0x0     /* We use /dev/fuse */
#define  PMNT_SOCKPAIR  0x1     /* We use socketpair */
#define  PMNT_DGRAM     0x2     /* We use SOCK_DGRAM sockets */


static int
access_mount(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(int fd, struct perfuse_mount_info *pmi, int sock_type)
{
       struct perfuse_mount_out *pmo;
       struct sockcred cred;
       int opt;
       char *cp;
       char *source = NULL;
       char *target = NULL;
       char *filesystemtype = NULL;
       long mountflags = 0;
       void *data = NULL;
       char *sock = NULL;

       pmo = (struct perfuse_mount_out *)
               perfused_recv_early(fd, &cred, sizeof(cred));

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

       /*
        * We do not need peer creds beyond this point
        */
       opt = 0;
       if (setsockopt(fd, SOL_LOCAL, LOCAL_CREDS, &opt, sizeof(opt)) != 0)
               DWARN("%s: setsockopt LOCAL_CREDS failed", __func__);

#ifdef PERFUSE_DEBUG
       if (perfuse_diagflags & PDF_MISC)
               DPRINTF("perfuse lengths: source = %"PRId32", "
                       "target = %"PRId32", filesystemtype = %"PRId32", "
                       "data = %"PRId32", sock = %"PRId32"\n",
                       pmo->pmo_source_len, pmo->pmo_target_len,
                       pmo->pmo_filesystemtype_len, pmo->pmo_data_len,
                       pmo->pmo_sock_len);
#endif
       cp = (char *)(void *)(pmo + 1);

       if (pmo->pmo_source_len != 0) {
               source = cp;
               cp += pmo->pmo_source_len;
       }

       if (pmo->pmo_target_len != 0) {
               target = cp;
               cp += pmo->pmo_target_len;
       }

       if (pmo->pmo_filesystemtype_len != 0) {
               filesystemtype = cp;
               cp += pmo->pmo_filesystemtype_len;
       }

       mountflags = pmo->pmo_mountflags;

       if (pmo->pmo_data_len != 0) {
               data = cp;
               cp += pmo->pmo_data_len;
       }

       if (pmo->pmo_sock_len != 0) {
               sock = cp;
               cp += pmo->pmo_sock_len;
       }

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

       pmi->pmi_uid = cred.sc_euid;

       /*
        * Connect to the remote socket if provided ans using SOCK_DGRAM
        */
       if ((sock_type == SOCK_DGRAM) && sock) {
               const struct sockaddr *sa;
               struct sockaddr_un sun;

               sa = (const struct sockaddr *)(void *)&sun;
               sun.sun_len = sizeof(sun);
               sun.sun_family = AF_LOCAL;
               strcpy(sun.sun_path, sock);

               if (connect(fd, sa, sun.sun_len) != 0)
                       DERR(EX_OSERR, "connect \"%s\" failed", sun.sun_path);
       }

       return;
}

static void
new_mount(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;
       int sock_type;
       char trace_file[MAXPATHLEN + 1];
       char trace_name[MAXPATHLEN + 1];
       ssize_t trace_namelen;
       int i;

       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...)
        */
       sock_type = pmnt_flags & PMNT_DGRAM ? SOCK_DGRAM : SOCK_SEQPACKET;
       get_mount_info(fd, &pmi, sock_type);

       /*
        * 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
        */
       (void)memset(&pc, 0, sizeof(pc));
       pc.pc_new_msg = perfused_new_pb;
       pc.pc_xchg_msg = perfused_xchg_pb;
       pc.pc_destroy_msg = (perfuse_destroy_msg_fn)puffs_framebuf_destroy;
       pc.pc_get_inhdr = perfused_get_inhdr;
       pc.pc_get_inpayload = perfused_get_inpayload;
       pc.pc_get_outhdr = perfused_get_outhdr;
       pc.pc_get_outpayload = perfused_get_outpayload;
       pc.pc_umount = perfused_umount;
       pc.pc_fsreq = perfused_gotframe;

       pu = perfuse_init(&pc, &pmi);

       puffs_framev_init(pu, perfused_readframe, perfused_writeframe,
                         perfused_cmpframe, pc.pc_fsreq, perfused_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 *)(intptr_t)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 perfused_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");

       /*
        * Setup trace file facility
        */
       perfused_mount = pu;

       trace_namelen = strlcpy(trace_name, pmi.pmi_target, MAXPATHLEN);
       for (i = 0; i < trace_namelen; i++)
               if (trace_name[i] == '/')
                       trace_name[i] = '-';

       (void)snprintf(trace_file, MAXPATHLEN, _PATH_VAR_RUN_PERFUSE_TRACE,
                      trace_name);

       if ((perfused_trace = fopen(trace_file, "w")) == NULL)
               DERR(EX_OSFILE,
                    "could not open \"%s\"",
                    _PATH_VAR_RUN_PERFUSE_TRACE);

       if (signal(SIGUSR1, sigusr1_handler) == SIG_ERR)
               DERR(EX_OSERR, "signal failed");

       /*
        * Hand over control to puffs main loop.
        */
       if (perfuse_mainloop(pu) != 0)
               DERRX(EX_SOFTWARE, "perfused_mainloop exit");

       /*
        * Normal return after unmount
        */
       return;
}

static int
parse_debug(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 if (strcmp(opt, "filename") == 0)
                       retval |= PDF_FILENAME;
               else if (strcmp(opt, "reize") == 0)
                       retval |= PDF_RESIZE;
               else
                       DWARNX("unknown debug flag \"%s\"", opt);
       }

       return retval;
}

/* ARGSUSED0 */
static void
siginfo_handler(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;
}

/* ARGSUSED0 */
static void
sigusr1_handler(int sig)
{
       if (perfuse_diagflags & PDF_TRACE) {
               perfuse_trace_dump(perfused_mount, perfused_trace);
               perfuse_diagflags &= ~PDF_TRACE;
               DPRINTF("trace dumped, trace disabled\n");
       } else {
               perfuse_diagflags |= PDF_TRACE;
               DPRINTF("trace enabled\n");
       }

       return;
}

static int
parse_options(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) == SIG_ERR)
                               DERR(EX_OSERR, "signal failed");
                       break;
               case 'f':
                       foreground = 1;
                       perfuse_diagflags |= PDF_MISC;
                       break;
               case 'i':
                       retval = atoi(optarg);
                       foreground = 1;
                       break;
               default:
                       DERRX(EX_USAGE, "%s [-fs] [-d classes] [-i fd]", argv[0]);
                       break;
               }
       }

       if (!foreground)
               perfuse_diagflags &= ~PDF_FOREGROUND;

       return retval;
}

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

       s = parse_options(argc, argv);

       if (perfuse_diagflags & PDF_SYSLOG)
               openlog("perfused", LOG_NDELAY, 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);
               exit(0);
       }

       s = perfused_open_sock();

#ifdef PERFUSE_DEBUG
       if (perfuse_diagflags & PDF_MISC)
               DPRINTF("perfused ready\n");
#endif
       len = sizeof(sock_type);
       if (getsockopt(s, SOL_SOCKET, SO_TYPE, &sock_type, &len) != 0)
               DERR(EX_OSERR, "getsockopt SO_TYPE failed");

       switch(sock_type) {
       case SOCK_DGRAM:
               new_mount(s, PMNT_DEVFUSE|PMNT_DGRAM);
               exit(0);
       case SOCK_SEQPACKET:
               if (listen(s, 0) != 0)
                       DERR(EX_OSERR, "listen failed");

               for (;;) {
                       int fd;
                       struct sockaddr_un sun;
                       struct sockaddr *sa;

                       len = sizeof(sun);
                       sa = (struct sockaddr *)(void *)&sun;
                       if ((fd = accept(s, sa, &len)) == -1)
                               DERR(EX_OSERR, "accept failed");

                       new_mount(fd, PMNT_DEVFUSE);
               }
       default:
               DERRX(EX_SOFTWARE, "unexpected so_type %d", sock_type);
               break;
       }

       /* NOTREACHED */
       return 0;
}

void
perfused_panic(void)
{
       DWARNX("filesystem crashed");
       exit(EX_OK);
}