/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * 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/types.h>
#include <sys/sbuf.h>
#include <sys/wait.h>

#include <ctype.h>
#include <err.h>
#include <errno.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'

static int      exec_shell(const char *, const char *, const char *);
static void     usage(void);

int
main(int argc, char *argv[])
{
        struct sbuf *cmdbuf;
        long arg_max;
        int ch, debug, i, magic, n, nargs, rval;
        size_t cmdsize;
        char buf[4];
        char *cmd, *name, *p, *shell, *slashp, *tmpshell;

        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 = optopt - '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';
                }

        /*
         * Figure out the shell and name arguments to pass to execl()
         * in exec_shell().  Always malloc() shell and just set name
         * to point at the last part of shell if there are any backslashes,
         * otherwise just set it to point at the space malloc()'d.  If
         * SHELL environment variable exists, replace contents of
         * shell with it.
         */
        shell = name = NULL;
        tmpshell = getenv("SHELL");
        shell = (tmpshell != NULL) ? strdup(tmpshell) : strdup(_PATH_BSHELL);
        if (shell == NULL)
                err(1, "strdup() failed");
        slashp = strrchr(shell, '/');
        name = (slashp != NULL) ? slashp + 1 : shell;

        /*
         * 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.  Save the
         * size to pass to snprintf().
         */
        if (n == 0) {
                cmdsize = strlen(argv[0]) + 9 * (sizeof(" %1") - 1) + 1;
                if ((cmd = malloc(cmdsize)) == NULL)
                        err(1, NULL);
                strlcpy(cmd, argv[0], cmdsize);

                /* 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);
                        strlcat(cmd, buf, cmdsize);
                }

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

        cmdbuf = sbuf_new(NULL, NULL, 1024, SBUF_AUTOEXTEND);
        if (cmdbuf == NULL)
                err(1, NULL);

        arg_max = sysconf(_SC_ARG_MAX);

        /*
         * (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) {
                sbuf_clear(cmdbuf);
                if (sbuf_cat(cmdbuf, "exec ") != 0)
                        err(1, "sbuf");
                /* Expand command argv references. */
                for (p = cmd; *p != '\0'; ++p) {
                        if (ISMAGICNO(p)) {
                                if (sbuf_cat(cmdbuf, argv[*++p - '0']) != 0)
                                        err(1, "sbuf");
                        } else {
                                if (sbuf_putc(cmdbuf, *p) != 0)
                                        err(1, "sbuf");
                        }
                        if (sbuf_len(cmdbuf) > arg_max)
                                errc(1, E2BIG, NULL);
                }

                /* Terminate the command string. */
                if (sbuf_finish(cmdbuf) != 0)
                        err(1, "sbuf");

                /* Run the command. */
                if (debug)
                        (void)printf("%s\n", sbuf_data(cmdbuf));
                else
                        if (exec_shell(sbuf_data(cmdbuf), shell, name))
                                rval = 1;
        }

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

/*
 * exec_shell --
 *      Execute a shell command using passed use_shell and use_name
 *      arguments.
 */
static int
exec_shell(const char *command, const char *use_shell, const char *use_name)
{
        pid_t pid;
        int omask, pstat;
        sig_t intsave, quitsave;

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

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

static void
usage(void)
{

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