cmd/mail/createmf.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 1995 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*  Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*    All Rights Reserved   */

#pragma ident   "%Z%%M% %I% %E% SMI"

#include "mail.h"
/*
    If mail file does not exist create it
*/
#ifdef OLD
void createmf(uid, file)
uid_t uid;
char *file;
{
    int fd;

    void (*istat)(), (*qstat)(), (*hstat)();

    if (access(file, A_EXIST) == CERROR) {
        istat = signal(SIGINT, SIG_IGN);
        qstat = signal(SIGQUIT, SIG_IGN);
        hstat = signal(SIGHUP, SIG_IGN);
        umask(0);
        if ((fd = creat(file, MFMODE)) == -1)
            sav_errno = errno;
        else
            close(fd);
        umask(7);
        (void) signal(SIGINT, istat);
        (void) signal(SIGQUIT, qstat);
        (void) signal(SIGHUP, hstat);
    }
}
#else

#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>

int accessmf(path)
char *path;
{

struct stat fsb,sb;
int mbfd;
tryagain:
    if (lstat(path, &sb)) {
        /* file/symlink does not exist, so create one */
        mbfd = open(path,
            O_APPEND|O_CREAT|O_EXCL|O_WRONLY, S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP);
        chmod(path, 0660);
        /* if someone create a symlink/file just ahead */
        /* of us, the create will failed with EEXIST   */
        /* This is what we want, because we do not     */
        /* want someone to re-direct our "create"      */
            /* request to a another location.              */
        if (mbfd == -1) {
            if (errno == EEXIST)
                goto tryagain;
        }

    /* file/symlink  exist, make sure it is not linked */
    } else if (sb.st_nlink != 1 || S_ISLNK(sb.st_mode)) {
        fprintf(stderr,
"%s: security violation, '%s' should not be linked to other file\n", program, path);
        sav_errno = errno;
        return -1;
    } else {
        /* if we get here, there is a pre-existing file, */
        /* and it is not a symlink...            */
        /* open it, and make sure it is the same file    */
        /* we lstat() before...                          */
        /* this is to guard against someone deleting the */
        /* old file and creat a new symlink in its place */
        /* We are not createing a new file here, but we  */
        /* do not want append to the worng file either   */
        mbfd = open(path, O_APPEND|O_WRONLY, 0);
        if (mbfd != -1 &&
            (fstat(mbfd, &fsb) || fsb.st_nlink != 1 ||
            S_ISLNK(fsb.st_mode) || sb.st_dev != fsb.st_dev ||
            sb.st_ino != fsb.st_ino)) {
            /*  file changed after open */
            fprintf(stderr, "%s: security violation, '%s' inode changed after open\n", program, path);
            (void)close(mbfd);
            return -1;
        }
    }

    if (mbfd == -1) {
        sav_errno = errno;
        return -1;
    }

    return mbfd;
}
#endif