/*
 * Module to work around a bug in Linux XFS:
 * http://oss.sgi.com/bugzilla/show_bug.cgi?id=280
 *
 * Copyright (c) Volker Lendecke 2010
 *
 * 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 3 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, see <http://www.gnu.org/licenses/>.
 */

#include "includes.h"
#include "system/filesys.h"
#include "smbd/smbd.h"

static int linux_xfs_sgid_mkdirat(vfs_handle_struct *handle,
		struct files_struct *dirfsp,
		const struct smb_filename *smb_fname,
		mode_t mode)
{
	struct smb_filename *dname = NULL;
	struct smb_filename *fname = NULL;
	int mkdir_res;
	int res;
	NTSTATUS status;

	DEBUG(10, ("Calling linux_xfs_sgid_mkdirat(%s)\n",
		smb_fname->base_name));

	mkdir_res = SMB_VFS_NEXT_MKDIRAT(handle,
			dirfsp,
			smb_fname,
			mode);
	if (mkdir_res == -1) {
		DEBUG(10, ("SMB_VFS_NEXT_MKDIRAT returned error: %s\n",
			   strerror(errno)));
		return mkdir_res;
	}

	fname = full_path_from_dirfsp_atname(talloc_tos(),
					     dirfsp,
					     smb_fname);
	if (fname == NULL) {
		return -1;
	}

	status = SMB_VFS_PARENT_PATHNAME(handle->conn,
					 talloc_tos(),
					 fname,
					 &dname,
					 NULL);
	if (!NT_STATUS_IS_OK(status)) {
		DBG_WARNING("SMB_VFS_PARENT_PATHNAME() failed with %s\n",
			nt_errstr(status));
		/* return success, we did the mkdir */
		return mkdir_res;
	}

	res = SMB_VFS_NEXT_STAT(handle, dname);
	if (res == -1) {
		DBG_DEBUG("NEXT_STAT(%s) failed: %s\n",
			  smb_fname_str_dbg(dname),
			  strerror(errno));
		/* return success, we did the mkdir */
		return mkdir_res;
	}
	if ((dname->st.st_ex_mode & S_ISGID) == 0) {
		/* No SGID to inherit */
		DEBUG(10, ("No SGID to inherit\n"));
		TALLOC_FREE(dname);
		return mkdir_res;
	}
	TALLOC_FREE(dname);

	res = SMB_VFS_NEXT_STAT(handle, fname);
	if (res == -1) {
		DBG_NOTICE("Could not stat just created dir %s: %s\n",
			   smb_fname_str_dbg(fname),
			   strerror(errno));
		/* return success, we did the mkdir */
		TALLOC_FREE(fname);
		return mkdir_res;
	}
	fname->st.st_ex_mode |= S_ISGID;
	fname->st.st_ex_mode &= ~S_IFDIR;

	/*
	 * Yes, we have to do this as root. If you do it as
	 * non-privileged user, XFS on Linux will just ignore us and
	 * return success. What can you do...
	 */
	become_root();
	res = SMB_VFS_NEXT_FCHMOD(handle, smb_fname->fsp, fname->st.st_ex_mode);
	unbecome_root();

	if (res == -1) {
		DBG_NOTICE("CHMOD(%s, %o) failed: %s\n",
			   smb_fname_str_dbg(fname),
			   (int)fname->st.st_ex_mode,
			   strerror(errno));
		/* return success, we did the mkdir */
		TALLOC_FREE(fname);
		return mkdir_res;
	}

	TALLOC_FREE(fname);
	return mkdir_res;
}

static struct vfs_fn_pointers linux_xfs_sgid_fns = {
	.mkdirat_fn = linux_xfs_sgid_mkdirat,
};

static_decl_vfs;
NTSTATUS vfs_linux_xfs_sgid_init(TALLOC_CTX *ctx)
{
	return smb_register_vfs(SMB_VFS_INTERFACE_VERSION,
				"linux_xfs_sgid", &linux_xfs_sgid_fns);
}