mount.fuse.c

/*
  FUSE: Filesystem in Userspace
  Copyright (C) 2001-2007  Miklos Szeredi <miklos@szeredi.hu>

  This program can be distributed under the terms of the GNU GPL.
  See the file COPYING.
*/

#include <config.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <stdint.h>

static char *progname;

static char *xstrdup(const char *s)
{
        char *t = strdup(s);
        if (!t) {
                fprintf(stderr, "%s: failed to allocate memory\n", progname);
                exit(1);
        }
        return t;
}

static void *xrealloc(void *oldptr, size_t size)
{
        void *ptr = realloc(oldptr, size);
        if (!ptr) {
                fprintf(stderr, "%s: failed to allocate memory\n", progname);
                exit(1);
        }
        return ptr;
}

static void add_arg(char **cmdp, const char *opt)
{
        size_t optlen = strlen(opt);
        size_t cmdlen = *cmdp ? strlen(*cmdp) : 0;
        if (optlen >= (SIZE_MAX - cmdlen - 4)/4) {
                fprintf(stderr, "%s: argument too long\n", progname);
                exit(1);
        }
        char *cmd = xrealloc(*cmdp, cmdlen + optlen * 4 + 4);
        char *s;
        s = cmd + cmdlen;
        if (*cmdp)
                *s++ = ' ';

        *s++ = '\'';
        for (; *opt; opt++) {
                if (*opt == '\'') {
                        *s++ = '\'';
                        *s++ = '\\';
                        *s++ = '\'';
                        *s++ = '\'';
                } else
                        *s++ = *opt;
        }
        *s++ = '\'';
        *s = '\0';
        *cmdp = cmd;
}

static char *add_option(const char *opt, char *options)
{
        int oldlen = options ? strlen(options) : 0;

        options = xrealloc(options, oldlen + 1 + strlen(opt) + 1);
        if (!oldlen)
                strcpy(options, opt);
        else {
                strcat(options, ",");
                strcat(options, opt);
        }
        return options;
}

int main(int argc, char *argv[])
{
        char *type = NULL;
        char *source;
        const char *mountpoint;
        char *basename;
        char *options = NULL;
        char *command = NULL;
        char *setuid = NULL;
        int i;
        int dev = 1;
        int suid = 1;

        progname = argv[0];
        basename = strrchr(argv[0], '/');
        if (basename)
                basename++;
        else
                basename = argv[0];

        if (strncmp(basename, "mount.fuse.", 11) == 0)
                type = basename + 11;
        if (strncmp(basename, "mount.fuseblk.", 14) == 0)
                type = basename + 14;

        if (type && !type[0])
                type = NULL;

        if (argc < 3) {
                fprintf(stderr,
                        "usage: %s %s destination [-t type] [-o opt[,opts...]]\n",
                        progname, type ? "source" : "type#[source]");
                exit(1);
        }

        source = argv[1];
        if (!source[0])
                source = NULL;

        mountpoint = argv[2];

        for (i = 3; i < argc; i++) {
                if (strcmp(argv[i], "-v") == 0) {
                        continue;
                } else if (strcmp(argv[i], "-t") == 0) {
                        i++;

                        if (i == argc) {
                                fprintf(stderr,
                                        "%s: missing argument to option '-t'\n",
                                        progname);
                                exit(1);
                        }
                        type = argv[i];
                        if (strncmp(type, "fuse.", 5) == 0)
                                type += 5;
                        else if (strncmp(type, "fuseblk.", 8) == 0)
                                type += 8;

                        if (!type[0]) {
                                fprintf(stderr,
                                        "%s: empty type given as argument to option '-t'\n",
                                        progname);
                                exit(1);
                        }
                } else  if (strcmp(argv[i], "-o") == 0) {
                        char *opts;
                        char *opt;
                        i++;
                        if (i == argc)
                                break;

                        opts = xstrdup(argv[i]);
                        opt = strtok(opts, ",");
                        while (opt) {
                                int j;
                                int ignore = 0;
                                const char *ignore_opts[] = { "",
                                                              "user",
                                                              "nofail",
                                                              "nouser",
                                                              "users",
                                                              "auto",
                                                              "noauto",
                                                              "_netdev",
                                                              NULL};
                                if (strncmp(opt, "setuid=", 7) == 0) {
                                        setuid = xstrdup(opt + 7);
                                        ignore = 1;
                                }
                                for (j = 0; ignore_opts[j]; j++)
                                        if (strcmp(opt, ignore_opts[j]) == 0)
                                                ignore = 1;

                                if (!ignore) {
                                        if (strcmp(opt, "nodev") == 0)
                                                dev = 0;
                                        else if (strcmp(opt, "nosuid") == 0)
                                                suid = 0;

                                        options = add_option(opt, options);
                                }
                                opt = strtok(NULL, ",");
                        }
                }
        }

        if (dev)
                options = add_option("dev", options);
        if (suid)
                options = add_option("suid", options);

        if (!type) {
                if (source) {
                        type = xstrdup(source);
                        source = strchr(type, '#');
                        if (source)
                                *source++ = '\0';
                        if (!type[0]) {
                                fprintf(stderr, "%s: empty filesystem type\n",
                                        progname);
                                exit(1);
                        }
                } else {
                        fprintf(stderr, "%s: empty source\n", progname);
                        exit(1);
                }
        }

        add_arg(&command, type);
        if (source)
                add_arg(&command, source);
        add_arg(&command, mountpoint);
        if (options) {
                add_arg(&command, "-o");
                add_arg(&command, options);
        }

        if (setuid && setuid[0]) {
                char *sucommand = command;
                command = NULL;
                add_arg(&command, "su");
                add_arg(&command, "-");
                add_arg(&command, setuid);
                add_arg(&command, "-c");
                add_arg(&command, sucommand);
        } else if (!getenv("HOME")) {
                /* Hack to make filesystems work in the boot environment */
                setenv("HOME", "/root", 0);
        }

        execl("/bin/sh", "/bin/sh", "-c", command, NULL);
        fprintf(stderr, "%s: failed to execute /bin/sh: %s\n", progname,
                strerror(errno));
        return 1;
}