util.c

linux下常用的网络工具的代码

/*-
 * Copyright (c) 1992, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * 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.
 * 4. 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.
 */

#ifndef lint
static char sccsid[] = "@(#)util.c	8.2 (Berkeley) 4/2/94";
#endif /* not lint */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <sys/param.h>
#ifdef HAVE_SYS_SYSMACROS_H
#include <sys/sysmacros.h>
#endif
#include <sys/stat.h>
#ifdef HAVE_SYS_WAIT_H
#include <sys/wait.h>
#endif

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

#include "extern.h"

char *
colon(char *cp)
{
	if (*cp == ':')		/* Leading colon is part of file name. */
		return (0);

	for (; *cp; ++cp) {
		if (*cp == ':')
			return (cp);
		if (*cp == '/')
			return (0);
	}
	return (0);
}

void
verifydir(char *cp)
{
	struct stat stb;

	if (!stat(cp, &stb)) {
		if (S_ISDIR(stb.st_mode))
			return;
		errno = ENOTDIR;
	}
	run_err("%s: %s", cp, strerror(errno));
	exit(1);
}

int
okname(char *cp0)
{
	int c;
	char *cp;

	cp = cp0;
	do {
		c = *cp;
		if (c & 0200)
			goto bad;
		if (!isalpha(c) && !isdigit(c) && c != '_' && c != '-')
			goto bad;
	} while (*++cp);
	return (1);

bad:	
	error (0, 0, "%s: invalid user name", cp0);
	return (0);
}

int
susystem(char *s, int userid)
{
	sig_t istat, qstat;
	int status, w;
	pid_t pid;

	pid = vfork();
	switch (pid) {
	case -1:
		return (127);

	case 0:
		(void)setuid(userid);
		execl(PATH_BSHELL, "sh", "-c", s, NULL);
		_exit(127);
	}
	istat = signal(SIGINT, SIG_IGN);
	qstat = signal(SIGQUIT, SIG_IGN);
	if (waitpid(pid, &status, 0) < 0)
		status = -1;
	(void)signal(SIGINT, istat);
	(void)signal(SIGQUIT, qstat);
	return (status);
}

BUF *
allocbuf(BUF *bp, int fd, int blksize)
{
	struct stat stb;
	size_t size;

	if (fstat(fd, &stb) < 0) {
		run_err("fstat: %s", strerror(errno));
		return (0);
	}
#ifndef roundup
#  define roundup(x, y)   ((((x)+((y)-1))/(y))*(y))
#endif
	size = roundup(BUFSIZ, blksize);
	if (size == 0)
		size = blksize;
	if (bp->cnt >= size)
		return (bp);
	if ((bp->buf = realloc(bp->buf, size)) == NULL) {
		bp->cnt = 0;
		run_err("%s", strerror(errno));
		return (0);
	}
	bp->cnt = size;
	return (bp);
}

RETSIGTYPE
lostconn(int signo)
{
	if (!iamremote)
		error (0, 0, "lost connection");
	exit(1);
}