/***************************************************************************
 *   Copyright (C) 2005, 2006 by Dmitry Morozhnikov   *
 *   dmiceman@mail.ru   *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *
 ***************************************************************************/


#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <linux/stat.h>
#include <unistd.h>
#include <getopt.h>
#include <mntent.h>
#include <sys/param.h>
#include <pwd.h>

#include <linux/iso_fs.h>

#define FUSE_USE_VERSION 314
#include <fuse.h>

#include <zlib.h>
#include <locale.h>
#include <langinfo.h>

#include "isofs.h"

#ifdef __GNUC__
# define UNUSED(x) x __attribute__((unused))
#else
# define UNUSED(x) x
#endif

static char *imagefile = NULL;
static char *mount_point = NULL;
static int image_fd = -1;

int maintain_mount_point;
int maintain_mtab;
char* iocharset;

char* normalize_name(const char* fname) {
    char* abs_fname = (char *) malloc(PATH_MAX);
    realpath(fname, abs_fname);
    // ignore errors from realpath()
    return abs_fname;
};

int check_mount_point() {
    struct stat st;
    int rc = lstat(mount_point, &st);
    if(rc == -1 && errno == ENOENT) {
        // directory does not exists, createcontext
        rc = mkdir(mount_point, 0777); // let`s underlying filesystem manage permissions
        if(rc != 0) {
            perror("Can`t create mount point");
            return -EIO;
        };
    } else if(rc == -1) {
        perror("Can`t check mount point");
        return -1;
    };
    return 0;
};

void del_mount_point() {
    int rc = rmdir(mount_point);
    if(rc != 0) {
        perror("Can`t delete mount point");
    };
};

char* get_mtab_path() {
    char* mtab_path = (char*) malloc(PATH_MAX);
    uid_t uid = getuid();
    struct passwd* passwd = getpwuid(uid);
    if(!passwd) {
        fprintf(stderr, "Can`t get home directory for user %d: %s\n", uid, strerror(errno));
        return NULL;
    };
    mtab_path[0] = 0;
    if(passwd->pw_dir) { // may be NULL, who know..
        strncpy(mtab_path, passwd->pw_dir, PATH_MAX - 16);
        mtab_path[PATH_MAX - 1] = 0;
    };
    strcat(mtab_path, "/.mtab.fuseiso");
    return mtab_path;
};

int add_mtab_record() {
    int rc;
    char* mtab_path = get_mtab_path();
    if(!mtab_path) {
        return -EIO;
    };
    int fd = open(mtab_path, O_RDWR | O_CREAT, 0644);
    if(fd < 0) {
        perror("Can`t open mtab");
        return -EIO;
    };
    rc = lockf(fd, F_LOCK, 0);
    if(rc != 0) {
        perror("Can`t lock mtab");
        return -EIO;
    };
    FILE* mtab = setmntent(mtab_path, "a");
    if(!mtab) {
        perror("Can`t open mtab");
        return -EIO;
    };
    struct mntent ent;
    ent.mnt_fsname = imagefile;
    ent.mnt_dir = mount_point;
    ent.mnt_type = "fuseiso";
    ent.mnt_opts = "defaults";
    ent.mnt_freq = 0;
    ent.mnt_passno = 0;    
    rc = addmntent(mtab, &ent);
    if(rc != 0) {
        perror("Can`t add mtab entry");
        return -EIO;
    };
    endmntent(mtab);
    rc = lockf(fd, F_ULOCK, 0);
    if(rc != 0) {
        perror("Can`t unlock mtab");
        return -EIO;
    };
    close(fd);
    free(mtab_path);
    return 0;
};

int del_mtab_record() {
    int rc;
    char* mtab_path = get_mtab_path();
    char new_mtab_path[PATH_MAX];
    if(!mtab_path) {
        return -EIO;
    };
    int fd = open(mtab_path, O_RDWR | O_CREAT, 0644);
    if(fd < 0) {
        perror("Can`t open mtab");
        return -EIO;
    };
    rc = lockf(fd, F_LOCK, 0);
    if(rc != 0) {
        perror("Can`t lock mtab");
        return -EIO;
    };
    strncpy(new_mtab_path, mtab_path, PATH_MAX - 16);
    new_mtab_path[PATH_MAX - 1] = 0;
    strcat(new_mtab_path, ".new");
    FILE* mtab = setmntent(mtab_path, "r");
    if(!mtab) {
        perror("Can`t open mtab");
        return -EIO;
    };
    FILE* new_mtab = setmntent(new_mtab_path, "a+");
    if(!new_mtab) {
        perror("Can`t open new mtab");
        return -EIO;
    };
    struct mntent* ent;
    while((ent = getmntent(mtab)) != NULL) {
        if(strcmp(ent->mnt_fsname, imagefile) == 0 && 
            strcmp(ent->mnt_dir, mount_point) == 0 &&
            strcmp(ent->mnt_type, "fuseiso") == 0) {
            // skip
        } else {
            rc = addmntent(new_mtab, ent);
            if(rc != 0) {
                perror("Can`t add mtab entry");
                return -EIO;
            };
        };
    };
    endmntent(mtab);
    endmntent(new_mtab);
    rc = rename(new_mtab_path, mtab_path);
    if(rc != 0) {
        perror("Can`t rewrite mtab");
        return -EIO;
    };
    rc = lockf(fd, F_ULOCK, 0);
    if(rc != 0) {
        perror("Can`t unlock mtab");
        return -EIO;
    };
    close(fd);
    free(mtab_path);
    return 0;
};

static int isofs_getattr(const char *path, struct stat *stbuf, struct fuse_file_info *UNUSED(fi))
{
    return isofs_real_getattr(path, stbuf);
}

static int isofs_readlink(const char *path, char *target, size_t size) {
    return isofs_real_readlink(path, target, size);
};

static int isofs_open(const char *path, struct fuse_file_info *UNUSED(fi))
{
    return isofs_real_open(path);
}

static int isofs_read(const char *path, char *buf, size_t size,
                     off_t offset, struct fuse_file_info *UNUSED(fi))
{
    return isofs_real_read(path, buf, size, offset);
}

static int isofs_flush(const char *UNUSED(path), struct fuse_file_info *UNUSED(fi)) {
    return 0;
};

static void* isofs_init(struct fuse_conn_info *UNUSED(conn), struct fuse_config *cfg) {
    int rc;
    if(maintain_mtab) {
        rc = add_mtab_record();
        if(rc != 0) {
            exit(EXIT_FAILURE);
        };
    };
    cfg->use_ino = 1;
    return isofs_real_init();
};

static void isofs_destroy(void* param) {
    if(maintain_mtab) {
        del_mtab_record();
    };
    return;
};

static int isofs_opendir(const char *path, struct fuse_file_info *UNUSED(fi)) {
    return isofs_real_opendir(path);
};

static int isofs_readdir(const char *path, void *buf, fuse_fill_dir_t filler, off_t UNUSED(offset),
    struct fuse_file_info *UNUSED(fi), enum fuse_readdir_flags UNUSED(flags)) {
    return isofs_real_readdir(path, buf, filler);
};

static int isofs_statfs(const char *UNUSED(path), struct statvfs *stbuf)
{
    return isofs_real_statfs(stbuf);
}

static struct fuse_operations isofs_oper = {
    .getattr    = isofs_getattr,
    .readlink   = isofs_readlink,
    .open       = isofs_open,
    .read       = isofs_read,
    .flush      = isofs_flush,
    .init       = isofs_init,
    .destroy    = isofs_destroy,
    .opendir    = isofs_opendir,
    .readdir    = isofs_readdir,
    .statfs     = isofs_statfs,
};

void usage(const char* prog) {
    printf("Version: %s\nUsage: %s [-n] [-p] [-c <iocharset>] [-h] <isofs_image_file> <mount_point> [<FUSE library options>]\n"
        "Where options are:\n"
        "    -n                 -- do NOT maintain file $HOME/.mtab.fuseiso\n"
        "    -p                 -- maintain mount point; \n"
        "                          create it if it does not exists and delete it on exit\n"
        "    -c <iocharset>     -- specify iocharset for Joliet filesystem\n"
        "    -h                 -- print this screen\n"
        "\nCommon FUSE library options are:\n"
        "    -o <opts>          -- specify comma-separated list of mount options\n"
        "    -s                 -- run single-threaded\n"
        "    -f                 -- run in foreground, do not daemonize\n"
        "    -d                 -- run in foreground and print debug information\n"
        "    -V                 -- print libfuse version information\n"
        "\nPlease consult with FUSE documentation for more information\n",
        VERSION, 
        prog);
};

int main(int argc, char *argv[])
{
    setlocale(LC_ALL, ""); // set current locale for proper iocharset
    
    // defaults
    maintain_mount_point = 0;
    maintain_mtab = 1;
    iocharset = NULL;

    char **fuseopts = reallocarray(NULL, 1, sizeof(*fuseopts));
    fuseopts[0] = argv[0];
    size_t fuseopts_cnt = 1;
    
    int c;
    char *s;
    while((c = getopt(argc, argv, "+npc:ho:sfdV")) > 0) {
        switch((char)c) {
            case 'n':
                maintain_mtab = 0;
                break;
            case 'p':
                maintain_mount_point = 1;
                break;
            case 'c':
                if(optarg) {
                    iocharset = optarg;
                };
                break;
            case 'h':
                usage(argv[0]);
                exit(0);
                break;
            case 'o':
                fuseopts = reallocarray(fuseopts, fuseopts_cnt + 2, sizeof(*fuseopts));
                fuseopts[fuseopts_cnt++] = "-o";
                fuseopts[fuseopts_cnt++] = optarg;
                break;
            case 's':
            case 'f':
            case 'd':
                fuseopts = reallocarray(fuseopts, fuseopts_cnt + 1, sizeof(*fuseopts));
                s = (char *)malloc(3);
                snprintf(s, 3, "-%c", c);
                fuseopts[fuseopts_cnt++] = s;
                break;
            case 'V':
                fuseopts = reallocarray(fuseopts, fuseopts_cnt + 1, sizeof(*fuseopts));
                fuseopts[fuseopts_cnt++] = "-V";
                return fuse_main(fuseopts_cnt, fuseopts, &isofs_oper, NULL);
                break;
            case '?':
            case ':':
                usage(argv[0]);
                exit(EXIT_FAILURE);
                break;
        };
    };
    
    if((argc - optind) < 2) {
        usage(argv[0]);
        exit(EXIT_FAILURE);
    };
    
    imagefile = normalize_name(argv[optind++]);
    
    image_fd = open(imagefile, O_RDONLY);
    if(image_fd == -1) {
        fprintf(stderr, "Supplied image file name: \"%s\"\n", imagefile);
        perror("Can`t open image file");
        exit(EXIT_FAILURE);
    };
    
    mount_point = normalize_name(argv[optind]);
    
    fuseopts = reallocarray(fuseopts, fuseopts_cnt + argc - optind, sizeof(*fuseopts));
    
    while(optind < argc) {
        fuseopts[fuseopts_cnt++] = argv[optind++];
    };
    
    if(!iocharset) {
        char *nlcharset = nl_langinfo(CODESET);
        if(nlcharset) {
            iocharset = (char *) malloc(strlen(nlcharset) + 9);
            strcpy(iocharset, nlcharset);
            strcat(iocharset, "//IGNORE");
        };
        if(!iocharset) {
            iocharset = "UTF-8//IGNORE";
        };
    };
    
    int rc;
    if(maintain_mount_point) {
        rc = check_mount_point();
        if(rc != 0) {
            exit(EXIT_FAILURE);
        };
    };
    if(maintain_mount_point) {
        rc = atexit(del_mount_point);
        if(rc != 0) {
            fprintf(stderr, "Can`t set exit function\n");
            exit(EXIT_FAILURE);
        }
    };
    
    // will exit in case of failure
    rc = isofs_real_preinit(imagefile, image_fd);
    
    return fuse_main(fuseopts_cnt, fuseopts, &isofs_oper, NULL);
};