/*

 * Copyright (C) 2012, 2014, 2016  J. Ali Harlow <ali@juiblex.co.uk>

 *

 * 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.,

 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

 */

#include "config.h"

#if ENABLE_ATOMIC && !HAVE_WINDOWS_KTM

#include <stdlib.h>

#include <stdio.h>

#include <string.h>

#include <unistd.h>

#include <fcntl.h>

#include "razor-internal.h"

/*

 * Emulated atomic support

 *

 * This implementation is better than nothing, but is certainly not atomic.

 * It does have a couple of advantages over atomic-none:

 *	- If a file operation fails while a package is being installed we

 *	  have a good chance of being able to rollback the transaction to

 *	  a well-known state.

 *	- We behave similarly to atomic-ktm in that changes are not visible

 *	  on disk to non-atomic operations (eg., scripts) until the atomic

 *	  is committed. This makes the testsuite more likely to pick up

 *	  problems that would otherwise only be found when using razor on

 *	  an MS-Windows system which supports KTM.

 */

#ifndef O_BINARY

#define O_BINARY	0

#endif

static void recursive_remove(const char *directory)

{

	void *dp;

	char *name, *buf;

	dp = razor_uri_opendir(directory, NULL);

	if (dp) {

		while((name = razor_uri_readdir(dp, NULL))) {

			buf = razor_concat(directory, "/", name, NULL);

			free(name);

			if (razor_uri_unlink(buf, NULL) < 0)

				recursive_remove(buf);

			free(buf);

		}

		razor_uri_closedir(dp, NULL);

	}

	rmdir(directory);

}

RAZOR_EXPORT struct razor_atomic *razor_atomic_open(const char *description)

{

	struct razor_atomic *atomic;

	atomic = zalloc(sizeof *atomic);

	atomic->description = strdup(description);

	return atomic;

}

RAZOR_EXPORT int razor_atomic_commit(struct razor_atomic *atomic)

{

	struct atomic_action *actions;

	if (razor_atomic_in_error_state(atomic))

		return -1;

	if (atomic->actions) {

		actions = atomic_action_list_reverse(atomic->actions);

		atomic->actions = NULL;

		actions = atomic_action_do(atomic, actions);

		atomic_action_free(actions);

	}

	if (atomic->toplevel) {

		recursive_remove(atomic->toplevel);

		free(atomic->toplevel);

		atomic->toplevel = NULL;

	}

	return razor_atomic_in_error_state(atomic);

}

RAZOR_EXPORT void razor_atomic_destroy(struct razor_atomic *atomic)

{

	if (atomic->actions) {

		atomic_action_free(atomic->actions);

		atomic->actions = NULL;

	}

	if (atomic->toplevel) {

		recursive_remove(atomic->toplevel);

		free(atomic->toplevel);

		atomic->toplevel = NULL;

	}

	if (atomic->error)

		razor_error_free(atomic->error);

	free(atomic->description);

	free(atomic);

}

/*

 * We need a toplevel directory in which to hold temporary files

 * before they are committed. Since we can generally assume that

 * we have write permissions anywhere on the filesystem in

 * question, the best location is at the relevant mount point.

 * The most common case where this assumption fails is when

 * testing, when the current directory is a good choice.

 */

static int

razor_atomic_set_toplevel_from_uri(struct razor_atomic *atomic,

				   const char *uri)

{

	if (razor_atomic_in_error_state(atomic))

		return -1;

	if (atomic->toplevel)

		return 0;

#ifdef MSWIN_API

	atomic->toplevel = razor_uri_mkdtemp_near(uri, "atomic-XXXXXX",

						   &atomic->error);

#else

	atomic->toplevel = razor_uri_mkdtemp_near(uri, ".atomic-XXXXXX",

						   &atomic->error);

#endif

	return !atomic->toplevel;

}

/*

 * If root_uri is empty, then uri can be a URI (but not a relative-ref; ie.,

 * a scheme must be specified). If root_uri is non-empty, then it must be a

 * URI (but not a relative-ref) and uri must be a non-empty path.

 */

RAZOR_EXPORT int

razor_atomic_make_dirs(struct razor_atomic *atomic, const char *root_uri,

		       const char *uri)

{

	struct atomic_action *a;

	struct razor_uri ru;

	struct razor_error *tmp_error = NULL;

	char *fakeroot = NULL;

	razor_atomic_set_toplevel_from_uri(atomic, *root_uri ? root_uri : uri);

	if (razor_atomic_in_error_state(atomic))

		return -1;

	if (!*root_uri) {

		if (razor_uri_parse(&ru, uri, &tmp_error)) {

			razor_atomic_propagate_error(atomic, tmp_error, NULL);

			return -1;

		}

		if (*ru.path == '/') {

			free(ru.path);

			ru.path = strdup("/");

		} else {

			free(ru.path);

			ru.path = strdup("");

		}

		fakeroot = razor_uri_recompose(&ru);

		razor_uri_destroy(&ru);

		root_uri = fakeroot;

		uri += strlen(fakeroot);

	}

	a = atomic_action_new(ACTION_MAKE_DIRS);

	a->args.uri = strdup(uri);

	a->args.u.make_dirs.root = strdup(root_uri);

	atomic->actions = atomic_action_list_prepend(atomic->actions, a);

	if (fakeroot)

		free(fakeroot);

	return 0;

}

RAZOR_EXPORT int

razor_atomic_remove(struct razor_atomic *atomic, const char *uri)

{

	struct atomic_action *a;

	razor_atomic_set_toplevel_from_uri(atomic, uri);

	if (razor_atomic_in_error_state(atomic))

		return -1;

	a = atomic_action_new(ACTION_REMOVE);

	a->args.uri = strdup(uri);

	atomic->actions = atomic_action_list_prepend(atomic->actions, a);

	return 0;

}

RAZOR_EXPORT int

razor_atomic_rename_file(struct razor_atomic *atomic, const char *old_uri,

			 const char *new_uri)

{

	struct atomic_action *a;

	razor_atomic_set_toplevel_from_uri(atomic, new_uri);

	if (razor_atomic_in_error_state(atomic))

		return -1;

	a = atomic_action_new(ACTION_MOVE);

	a->args.uri = strdup(old_uri);

	a->args.u.move.dest = strdup(new_uri);

	atomic->actions = atomic_action_list_prepend(atomic->actions, a);

	return 0;

}

RAZOR_EXPORT int

razor_atomic_create_dir(struct razor_atomic *atomic, const char *uri,

			mode_t mode)

{

	struct atomic_action *a;

	razor_atomic_set_toplevel_from_uri(atomic, uri);

	if (razor_atomic_in_error_state(atomic))

		return -1;

	a = atomic_action_new(ACTION_CREATE_DIR);

	a->args.uri = strdup(uri);

	a->args.u.create_dir.mode = mode;

	atomic->actions = atomic_action_list_prepend(atomic->actions, a);

	return 0;

}

RAZOR_EXPORT int

razor_atomic_create_symlink(struct razor_atomic *atomic, const char *target,

			    const char *uri)

{

#if HAVE_SYMLINK

	struct atomic_action *a;

	razor_atomic_set_toplevel_from_uri(atomic, uri);

#endif

	if (razor_atomic_in_error_state(atomic))

		return -1;

#if HAVE_SYMLINK

	a = atomic_action_new(ACTION_CREATE_SYMLINK);

	a->args.uri = strdup(uri);

	a->args.u.create_symlink.target = strdup(target);

	atomic->actions = atomic_action_list_prepend(atomic->actions, a);

	return 0;

#else

	atomic->error = razor_error_new_str(RAZOR_POSIX_ERROR, ENOSYS, NULL,

					    "Symbolic links not supported "

					    "on this platform");

	return -1;

#endif

}

RAZOR_EXPORT int

razor_atomic_create_file(struct razor_atomic *atomic, const char *uri,

                         mode_t mode)

{

	int fd;

	struct atomic_action *a;

	char *tmpnam;

	razor_atomic_set_toplevel_from_uri(atomic, uri);

	if (razor_atomic_in_error_state(atomic))

		return -1;

	tmpnam = atomic_action_attic_tmpnam(atomic);

	fd = razor_uri_open(tmpnam, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY,

			    mode & (S_IRWXU | S_IRWXG | S_IRWXO),

			    &atomic->error);

	if (fd >= 0) {

		a = atomic_action_new(ACTION_MOVE);

		a->args.uri = tmpnam;

		a->args.u.move.dest = strdup(uri);

		atomic->actions = atomic_action_list_prepend(atomic->actions,

							     a);

	}

	return fd;

}

#endif	/* ENABLE_ATOMIC && !HAVE_WINDOWS_KTM */