/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright (c) 2001 by Sun Microsystems, Inc.
 * All rights reserved.
 */

/*
 * runat: run a command in attribute directory.
 *
 * runat file [command]
 *
 * when command is not specified an interactive shell is started
 * in the attribute directory.
 */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <libintl.h>
#include <errno.h>
#include <strings.h>

static void
usage()
{
        (void) fprintf(stderr, gettext("usage: runat filename [command]\n"));
}

int
main(int argc, char *argv[])
{
        int fd;
        int dirfd;
        int i;
        int argslen;
        char *shell;
        char *args[4];
        char *cmdargs;

        if (argc < 2) {
                usage();
                exit(127);
        }

        if ((fd = open64(argv[1], O_RDONLY)) == -1) {
                (void) fprintf(stderr,
                    gettext("runat: cannot open %s: %s\n"), argv[1],
                    strerror(errno));
                exit(125);
        }

        if ((dirfd = openat64(fd, ".", O_RDONLY|O_XATTR)) == -1) {
                (void) fprintf(stderr,
                    gettext("runat: cannot open attribute"
                    " directory for %s: %s\n"), argv[1], strerror(errno));
                exit(125);
        }

        (void) close(fd);

        if (fchdir(dirfd) == -1) {
                (void) fprintf(stderr,
                    gettext("runat: cannot fchdir to attribute"
                    " directory: %s\n"), strerror(errno));
                exit(125);
        }

        if (argc < 3) {
                shell = getenv("SHELL");
                if (shell == NULL) {
                        (void) fprintf(stderr,
                            gettext(
                            "runat: shell not found, using /bin/sh\n"));
                        shell = "/bin/sh";
                }

                (void) execl(shell, shell, NULL);
                (void) fprintf(stderr,
                    gettext("runat: Failed to exec %s: %s\n"), shell,
                    strerror(errno));
                return (126);
        }

        /*
         * Count up the size of all of the args
         */

        for (i = 2, argslen = 0; i < argc; i++) {
                argslen += strlen(argv[i]) + 1;
        }

        cmdargs = calloc(1, argslen);
        if (cmdargs == NULL) {
                (void) fprintf(stderr, gettext(
                    "runat: failed to allocate memory for"
                    " command arguments: %s\n"), strerror(errno));
                exit(126);
        }


        /*
         * create string with all of the args concatenated together
         * This is done so that the shell will interpret the args
         * and do globbing if necessary.
         */
        for (i = 2; i < argc; i++) {
                if (strlcat(cmdargs, argv[i], argslen) >= argslen) {
                        (void) fprintf(stderr, gettext(
                            "runat: arguments won't fit in"
                            " allocated buffer\n"));
                        exit(126);
                }

                /*
                 * tack on a space if there are more args
                 */
                if ((i + 1) < argc) {
                        if (strlcat(cmdargs, " ", argslen) >= argslen) {
                                (void) fprintf(stderr, gettext(
                                    "runat: arguments won't fit in"
                                    " allocated buffer\n"));
                                exit(126);
                        }
                }

        }

        args[0] = "/bin/sh";
        args[1] = "-c";
        args[2] = cmdargs;
        args[3] = NULL;
        (void) execvp(args[0], args);
        (void) fprintf(stderr, gettext("runat: Failed to exec %s: %s\n"),
            argv[0], strerror(errno));
        return (126);
}