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/*	$OpenBSD: apply.c,v 1.27 2015/10/10 17:48:34 deraadt 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.
 */

#define _GNU_SOURCE

#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>

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

int
main(int argc, char *argv[])
{
	int ch, clen, debug, i, l, magic, n, nargs, rval;
	char *c, *c2, *cmd, *p, *q;
	size_t len;

	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[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 (p[0] == magic &&
		    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 (n == 0) {
		len = sizeof("exec ") - 1 +
		    strlen(argv[0]) + 9 * (sizeof(" %1") - 1) + 1;
		if ((cmd = malloc(len)) == NULL)
			err(1, NULL);

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

		l = snprintf(cmd, len, "exec %s", argv[0]);
		if (l >= len || l == -1)
			errx(1, "error building exec string");
		len -= l;
		p = cmd + l;
		
		for (i = 1; i <= nargs; i++) {
			l = snprintf(p, len, " %c%d", magic, i);
			if (l >= len || l == -1)
				errx(1, "error numbering arguments");
			len -= l;
			p += l;
		}

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

	/*
	 * (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) {
			if ((c2 = realloc(c, l)) == NULL)
				err(1, NULL);
			c = c2;
			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') {
				strlcpy(q, argv[(++p)[0] - '0'], c + clen - q);
				q += strlen(q);
			} else
				*q++ = *p;

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

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