vifs.tproj/vifs.c

   1 /*
   2  * Copyright (c) 2005-2016 Apple Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22
  23 #include <sys/errno.h>
  24 #include <sys/types.h>
  25 #include <sys/stat.h>
  26 #include <sys/wait.h>
  27
  28 #include <err.h>
  29 #include <fcntl.h>
  30 #include <fstab.h>
  31 #include <stdio.h>
  32 #include <stdlib.h>
  33 #include <string.h>
  34 #include <paths.h>
  35 #include <unistd.h>
  36 #include <signal.h>
  37
  38 char *warning = "\
  39 #\n\
  40 # Warning - this file should only be modified with vifs(8)\n\
  41 #\n\
  42 # Failure to do so is unsupported and may be destructive.\n\
  43 #\n";
  44
  45 int
  46 main(int argc, char *argv[])
  47 {
  48         struct stat sb;
  49         int fd, x;
  50         uid_t euid;
  51         pid_t editpid;
  52         char *p, *editor;
  53
  54         if (argc != 1) {
  55                 printf("usage: vifs\n");
  56                 exit(1);
  57         }
  58
  59         euid = geteuid();
  60         if (euid != 0)
  61                 errx(1, "need to run as root");
  62
  63         /* examine the existing fstab, try to create it if needed */
  64         if (stat(_PATH_FSTAB, &sb) < 0) {
  65                 if (errno == ENOENT) {
  66                         fd = open(_PATH_FSTAB, O_CREAT | O_WRONLY,
  67                              S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH);
  68                         if (fd < 0)
  69                                 errx(1, "error creating %s", _PATH_FSTAB);
  70                         write(fd, warning, strlen(warning));
  71                         close(fd);
  72                 } else {
  73                         errx(1, "could not stat %s", _PATH_FSTAB);
  74                 }
  75         }
  76
  77         /* prepare the file for the editor */
  78         fd = open(_PATH_FSTAB, O_RDONLY, 0);
  79         if (fd < 0)
  80                 errx(1, "error opening %s", _PATH_FSTAB);
  81
  82         x = fcntl(fd, F_SETFD, 1);
  83         if (x < 0)
  84                 errx(1, "error setting close on exit");
  85
  86         x = flock(fd, LOCK_EX | LOCK_NB);
  87         if (x != 0)
  88                 errx(1, "file is busy");
  89
  90         /* obtain and invoke the editor */
  91         editor = getenv("EDITOR");
  92         if (editor == NULL)
  93                 editor = _PATH_VI;
  94         p = strrchr(editor, '/');
  95         if (p != NULL)
  96                 ++p;
  97         else
  98                 p = editor;
  99
 100         editpid = vfork();
 101         if (editpid == 0) {
 102                 execlp(editor, p, _PATH_FSTAB, NULL);
 103                 _exit(1);
 104         }
 105
 106         for ( ; ; ) {
 107                 editpid = waitpid(editpid, (int *)&x, WUNTRACED);
 108                 if (editpid == -1)
 109                         errx(1, "editing error");
 110                 else if (WIFSTOPPED(x))
 111                         raise(WSTOPSIG(x));
 112                 else if (WIFEXITED(x) && WEXITSTATUS(x) == 0)
 113                         break;
 114                 else
 115                         errx(1, "editing error");
 116         }
 117
 118         /* let process death clean up locks and file descriptors */
 119         return 0;
 120 }