unionfs.c

/*
*
* This is offered under a BSD-style license. This means you can use the code for whatever you
* desire in any way you may want but you MUST NOT forget to give me appropriate credits when
* spreading your work which is based on mine. Something like "original implementation by Radek
* Podgorny" should be fine.
*
* License: BSD-style license
* Copyright: Radek Podgorny <radek@podgorny.cz>,
*            Bernd Schubert <bernd-schubert@gmx.de>
*/

#include <fuse.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>

#include "unionfs.h"
#include "debug.h"
#include "opts.h"
#include "usyslog.h"

static struct fuse_opt unionfs_opts[] = {
	FUSE_OPT_KEY("chroot=%s,", KEY_CHROOT),
	FUSE_OPT_KEY("cow", KEY_COW),
	FUSE_OPT_KEY("even", KEY_EVEN_PLACEMENT),
	FUSE_OPT_KEY("debug_file=%s", KEY_DEBUG_FILE),
	FUSE_OPT_KEY("dirs=%s", KEY_DIRS),
	FUSE_OPT_KEY("--help", KEY_HELP),
	FUSE_OPT_KEY("-h", KEY_HELP),
	FUSE_OPT_KEY("hide_meta_dir", KEY_HIDE_METADIR),
	FUSE_OPT_KEY("hide_meta_files", KEY_HIDE_META_FILES),
	FUSE_OPT_KEY("max_files=%s", KEY_MAX_FILES),
	FUSE_OPT_KEY("noinitgroups", KEY_NOINITGROUPS),
	FUSE_OPT_KEY("relaxed_permissions", KEY_RELAXED_PERMISSIONS),
	FUSE_OPT_KEY("statfs_omit_ro", KEY_STATFS_OMIT_RO),
	FUSE_OPT_KEY("--version", KEY_VERSION),
	FUSE_OPT_KEY("-V", KEY_VERSION),
	FUSE_OPT_END
};

int main(int argc, char *argv[]) {
	struct fuse_args args = FUSE_ARGS_INIT(argc, argv);

	init_syslog();
	uopt_init();

	if (fuse_opt_parse(&args, NULL, unionfs_opts, unionfs_opt_proc) == -1) RETURN(1);

	if (uopt.debug)	debug_init();

	if (!uopt.doexit) {
		if (uopt.nbranches == 0) {
			printf("You need to specify at least one branch!\n");
			RETURN(1);
		}
	}

	// enable fuse permission checks, we need to set this, even we we are
	// not root, since we don't have our own access() function
	uid_t uid = getuid();
	gid_t gid = getgid();
	bool default_permissions = true;

	if (uid != 0 && gid != 0 && uopt.relaxed_permissions) {
		default_permissions = false;
	} else if (uopt.relaxed_permissions) {
		// protect the user of a very critical security issue
		fprintf(stderr, "Relaxed permissions disallowed for root!\n");
		exit(1);
	}

	if (default_permissions) {
		if (fuse_opt_add_arg(&args, "-odefault_permissions")) {
			fprintf(stderr, "Severe failure, can't enable permssion checks, aborting!\n");
			exit(1);
		}
	}
	unionfs_post_opts();

#ifdef FUSE_CAP_BIG_WRITES
	/* libfuse > 0.8 supports large IO, also for reads, to increase performance
	 * We support any IO sizes, so lets enable that option */
	if (fuse_opt_add_arg(&args, "-obig_writes")) {
		fprintf(stderr, "Failed to enable big writes!\n");
		exit(1);
	}
#endif

	umask(0);
	srand(time(NULL));
	int res = fuse_main(args.argc, args.argv, &unionfs_oper, NULL);
	RETURN(uopt.doexit ? uopt.retval : res);
}