usr/src/cmd/mail/createmf.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*
  23  * Copyright 1995 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 /*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
  28 /*        All Rights Reserved   */
  29
  30 #pragma ident   "%Z%%M% %I%     %E% SMI"
  31
  32 #include "mail.h"
  33 /*
  34         If mail file does not exist create it
  35 */
  36 #ifdef OLD
  37 void createmf(uid, file)
  38 uid_t uid;
  39 char *file;
  40 {
  41         int fd;
  42
  43         void (*istat)(), (*qstat)(), (*hstat)();
  44
  45         if (access(file, A_EXIST) == CERROR) {
  46                 istat = signal(SIGINT, SIG_IGN);
  47                 qstat = signal(SIGQUIT, SIG_IGN);
  48                 hstat = signal(SIGHUP, SIG_IGN);
  49                 umask(0);
  50                 if ((fd = creat(file, MFMODE)) == -1)
  51                         sav_errno = errno;
  52                 else
  53                         close(fd);
  54                 umask(7);
  55                 (void) signal(SIGINT, istat);
  56                 (void) signal(SIGQUIT, qstat);
  57                 (void) signal(SIGHUP, hstat);
  58         }
  59 }
  60 #else
  61
  62 #include <sys/stat.h>
  63 #include <fcntl.h>
  64 #include <stdio.h>
  65
  66 int accessmf(path)
  67 char *path;
  68 {
  69
  70 struct stat fsb,sb;
  71 int mbfd;
  72 tryagain:
  73         if (lstat(path, &sb)) {
  74                 /* file/symlink does not exist, so create one */
  75                 mbfd = open(path,
  76                     O_APPEND|O_CREAT|O_EXCL|O_WRONLY, S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP);
  77                 chmod(path, 0660);
  78                 /* if someone create a symlink/file just ahead */
  79                 /* of us, the create will failed with EEXIST   */
  80                 /* This is what we want, because we do not     */
  81                 /* want someone to re-direct our "create"      */
  82                 /* request to a another location.              */
  83                 if (mbfd == -1) {
  84                         if (errno == EEXIST)
  85                                 goto tryagain;
  86                 }
  87
  88         /* file/symlink  exist, make sure it is not linked */
  89         } else if (sb.st_nlink != 1 || S_ISLNK(sb.st_mode)) {
  90                 fprintf(stderr,
  91 "%s: security violation, '%s' should not be linked to other file\n", program, path);
  92                 sav_errno = errno;
  93                 return -1;
  94         } else {
  95                 /* if we get here, there is a pre-existing file, */
  96                 /* and it is not a symlink...                    */
  97                 /* open it, and make sure it is the same file    */
  98                 /* we lstat() before...                          */
  99                 /* this is to guard against someone deleting the */
 100                 /* old file and creat a new symlink in its place */
 101                 /* We are not createing a new file here, but we  */
 102                 /* do not want append to the worng file either   */
 103                 mbfd = open(path, O_APPEND|O_WRONLY, 0);
 104                 if (mbfd != -1 &&
 105                     (fstat(mbfd, &fsb) || fsb.st_nlink != 1 ||
 106                     S_ISLNK(fsb.st_mode) || sb.st_dev != fsb.st_dev ||
 107                     sb.st_ino != fsb.st_ino)) {
 108                         /*  file changed after open */
 109                         fprintf(stderr, "%s: security violation, '%s' inode changed after open\n", program, path);
 110                         (void)close(mbfd);
 111                         return -1;
 112                 }
 113         }
 114
 115         if (mbfd == -1) {
 116                 sav_errno = errno;
 117                 return -1;
 118         }
 119
 120         return mbfd;
 121 }
 122 #endif