/*      $NetBSD: apply.c,v 1.19 2016/03/12 22:28:04 dholland Exp $      */

/*-
 * Copyright (c) 1994
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Jan-Simon Pendry.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/cdefs.h>
#ifndef lint
#if 0
static char sccsid[] = "@(#)apply.c     8.4 (Berkeley) 4/4/94";
#else
__RCSID("$NetBSD: apply.c,v 1.19 2016/03/12 22:28:04 dholland Exp $");
#endif
#endif /* not lint */

#include <sys/wait.h>

#include <ctype.h>
#include <err.h>
#include <paths.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

static __dead void usage(void);
static int shell_system(const char *);

int
main(int argc, char *argv[])
{
        size_t clen, l;
        int ch, debug, i, magic, n, nargs, rval;
        char *c, *cmd, *p, *q, *nc;

        (void)setprogname(argv[0]);     /* for portability */

        /* Option defaults */
        debug = 0;
        magic = '%';
        nargs = -1;

        while ((ch = getopt(argc, argv, "a:d0123456789")) != -1) {
                switch (ch) {
                case 'a':
                        if (optarg[1] != '\0')
                                errx(EXIT_FAILURE,
                                    "Illegal magic character specification.");
                        magic = optarg[0];
                        break;
                case 'd':
                        debug = 1;
                        break;
                case '0': case '1': case '2': case '3': case '4':
                case '5': case '6': case '7': case '8': case '9':
                        if (nargs != -1)
                                errx(EXIT_FAILURE,
                                    "Only one -# argument may be specified.");
                        nargs = optopt - '0';
                        break;
                default:
                        usage();
                }
        }
        argc -= optind;
        argv += optind;

        if (argc < 2)
                usage();

        /*
         * The command to run is now argv[0], and the args are argv[1+].
         * Look for %digit references in the command, remembering the
         * largest one.
         */
        n = 0;
        for (p = argv[0]; p[0] != '\0'; ++p) {
                if (p[0] == magic && p[1] != '\0' &&
                    isdigit((unsigned char)p[1]) && p[1] != '0') {
                        ++p;
                        if (p[0] - '0' > n)
                                n = p[0] - '0';
                }
        }

        /*
         * If there were any %digit references, then use those, otherwise
         * build a new command string with sufficient %digit references at
         * the end to consume (nargs) arguments each time round the loop.
         * Allocate enough space to hold the maximum command.
         */
        if ((cmd = malloc(sizeof("exec ") - 1 +
            strlen(argv[0]) + 9 * (sizeof(" %1") - 1) + 1)) == NULL)
                err(EXIT_FAILURE, "malloc");

        if (n == 0) {
                /* If nargs not set, default to a single argument. */
                if (nargs == -1)
                        nargs = 1;

                p = cmd;
                p += sprintf(cmd, "exec %s", argv[0]);
                for (i = 1; i <= nargs; i++)
                        p += sprintf(p, " %c%d", magic, i);

                /*
                 * If nargs set to the special value 0, eat a single
                 * argument for each command execution.
                 */
                if (nargs == 0)
                        nargs = 1;
        } else {
                (void)sprintf(cmd, "exec %s", argv[0]);
                nargs = n;
        }

        /*
         * Grab some space in which to build the command.  Allocate
         * as necessary later, but no reason to build it up slowly
         * for the normal case.
         */
        if ((c = malloc(clen = 1024)) == NULL)
                err(EXIT_FAILURE, "malloc");

        /*
         * (argc) and (argv) are still offset by one to make it simpler to
         * expand %digit references.  At the end of the loop check for (argc)
         * equals 1 means that all the (argv) has been consumed.
         */
        for (rval = 0; argc > nargs; argc -= nargs, argv += nargs) {
                /*
                 * Find a max value for the command length, and ensure
                 * there's enough space to build it.
                 */
                for (l = strlen(cmd), i = 0; i < nargs; i++)
                        l += strlen(argv[i+1]);
                if (l > clen) {
                        nc = realloc(c, l);
                        if (nc == NULL)
                                err(EXIT_FAILURE, "malloc");
                        c = nc;
                        clen = l;
                }

                /* Expand command argv references. */
                for (p = cmd, q = c; *p != '\0'; ++p) {
                        if (p[0] == magic && isdigit((unsigned char)p[1]) &&
                            p[1] != '0')
                                q += sprintf(q, "%s", argv[(++p)[0] - '0']);
                        else
                                *q++ = *p;
                }

                /* Terminate the command string. */
                *q = '\0';

                /* Run the command. */
                if (debug)
                        (void)printf("%s\n", c);
                else if (shell_system(c))
                        rval = 1;
        }

        if (argc != 1)
                errx(EXIT_FAILURE,
                    "Expecting additional argument%s after \"%s\"",
                    (nargs - argc) ? "s" : "", argv[argc - 1]);
        return rval;
}

/*
 * shell_system --
 *      Private version of system(3).  Use the user's SHELL environment
 *      variable as the shell to execute.
 */
static int
shell_system(const char *command)
{
        static const char *name, *shell;
        int status;
        int omask;
        pid_t pid;
        sig_t intsave, quitsave;

        if (shell == NULL) {
                if ((shell = getenv("SHELL")) == NULL)
                        shell = _PATH_BSHELL;
                if ((name = strrchr(shell, '/')) == NULL)
                        name = shell;
                else
                        ++name;
        }

        if (!command) {
                /* just checking... */
                return(1);
        }

        omask = sigblock(sigmask(SIGCHLD));
        switch (pid = vfork()) {
        case -1:
                /* error */
                err(EXIT_FAILURE, "vfork");
                /*NOTREACHED*/
        case 0:
                /* child */
                (void)sigsetmask(omask);
                (void)execl(shell, name, "-c", command, (char *)NULL);
                warn("%s", shell);
                _exit(1);
                /*NOTREACHED*/
        default:
                /* parent */
                intsave = signal(SIGINT, SIG_IGN);
                quitsave = signal(SIGQUIT, SIG_IGN);
                pid = waitpid(pid, &status, 0);
                (void)sigsetmask(omask);
                (void)signal(SIGINT, intsave);
                (void)signal(SIGQUIT, quitsave);
                return pid == -1 ? -1 : status;
        }
        /*NOTREACHED*/
}

static __dead void
usage(void)
{

        (void)fprintf(stderr,
            "usage: %s [-a magic] [-0123456789] command arguments ...\n",
            getprogname());
        exit(1);
}