/*      $OpenBSD: apply.c,v 1.29 2018/04/01 17:45:05 bluhm Exp $        */
/*      $NetBSD: apply.c,v 1.3 1995/03/25 03:38:23 glass 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/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>

#define ISMAGICNO(p) \
            (p)[0] == magic && isdigit((unsigned char)(p)[1]) && (p)[1] != '0'

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

char    *str;
size_t   sz;

void
stradd(char *p)
{
        size_t n;

        n = strlen(p);
        if (str == NULL) {
                sz = (n / 1024 + 1) * 1024;
                if ((str = malloc(sz)) == NULL)
                        err(1, "malloc");
                *str = '\0';
        } else if (sz - strlen(str) <= n) {
                sz += (n / 1024 + 1) * 1024;
                if ((str = realloc(str, sz)) == NULL)
                        err(1, "realloc");
        }
        strlcat(str, p, sz);
}

void
strset(char *p)
{
        if (str != NULL)
                str[0] = '\0';
        stradd(p);
}

int
main(int argc, char *argv[])
{
        int ch, debug, i, magic, n, nargs, rval;
        char buf[4], *cmd, *p;

        if (pledge("stdio proc exec", NULL) == -1)
                err(1, "pledge");

        debug = 0;
        magic = '%';            /* Default magic char is `%'. */
        nargs = -1;
        while ((ch = getopt(argc, argv, "a:d0123456789")) != -1)
                switch (ch) {
                case 'a':
                        if (optarg[0] == '\0' || optarg[1] != '\0')
                                errx(1,
                                    "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(1,
                                    "only one -# argument may be specified.");
                        nargs = ch - '0';
                        break;
                default:
                        usage();
                }
        argc -= optind;
        argv += optind;

        if (argc < 2)
                usage();

        /*
         * The command to run is argv[0], and the args are argv[1..].
         * Look for %digit references in the command, remembering the
         * largest one.
         */
        for (n = 0, p = argv[0]; *p != '\0'; ++p)
                if (ISMAGICNO(p)) {
                        ++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.
         */
        strset(argv[0]);
        if (n == 0) {
                /* If nargs not set, default to a single argument. */
                if (nargs == -1)
                        nargs = 1;

                for (i = 1; i <= nargs; i++) {
                        snprintf(buf, sizeof(buf), " %c%d", magic, i);
                        stradd(buf);
                }

                /*
                 * If nargs set to the special value 0, eat a single
                 * argument for each command execution.
                 */
                if (nargs == 0)
                        nargs = 1;
        } else
                nargs = n;
        if ((cmd = strdup(str)) == NULL)
                err(1, "strdup");

        /*
         * (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) {
                strset("exec ");

                /* Expand command argv references. */
                for (p = cmd; *p != '\0'; ++p)
                        if (ISMAGICNO(p))
                                stradd(argv[*(++p) - '0']);
                        else {
                                strlcpy(buf, p, 2);
                                stradd(buf);
                        }

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

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

/*
 * mysystem --
 *      Private version of system(3).  Use the user's SHELL environment
 *      variable as the shell to execute.
 */
static int
mysystem(const char *command)
{
        static const char *name, *shell;
        pid_t pid;
        int pstat;
        sigset_t mask, omask;
        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);

        sigemptyset(&mask);
        sigaddset(&mask, SIGCHLD);
        sigprocmask(SIG_BLOCK, &mask, &omask);
        switch(pid = fork()) {
        case -1:                        /* error */
                err(1, "fork");
        case 0:                         /* child */
                sigprocmask(SIG_SETMASK, &omask, NULL);
                execl(shell, name, "-c", command, (char *)NULL);
                err(1, "%s", shell);
        }
        intsave = signal(SIGINT, SIG_IGN);
        quitsave = signal(SIGQUIT, SIG_IGN);
        pid = waitpid(pid, &pstat, 0);
        sigprocmask(SIG_SETMASK, &omask, NULL);
        (void)signal(SIGINT, intsave);
        (void)signal(SIGQUIT, quitsave);
        return(pid == -1 ? -1 : pstat);
}

__dead void
usage(void)
{
        (void)fprintf(stderr,
            "usage: apply [-#] [-d] [-a magic] command argument ...\n");
        exit(1);
}