i386/87208: /dev/cuad[0/1] bad file descriptor error during mgetty read

[HASHI Hiroaki]

The following reply was made to PR i386/87208; it has been noted by GNATS.

From: HASHI Hiroaki <hashiz at tomba.cskk-sv.co.jp>
To: bug-followup at FreeBSD.org, norbert at feu-nrmf.ph
Cc:  
Subject: Re: i386/87208: /dev/cuad[0/1] bad file descriptor error during
 mgetty read
Date: Tue, 18 Oct 2005 18:30:58 +0900 (JST)

 In this case, mgetty open a /dev/cuad? and dup(2) to stdin.
 
     int fd;
     
     fd = open(devname, O_RDWR | O_NDELAY | O_NOCTTY );
 
     /* make new fd == stdin if it isn't already */
 
     if (fd > 0)
     {
         (void) close(0);
 --->    if (dup(fd) != 0)
         {
             lprintf( L_FATAL, "mod: cannot make %s stdin", devname );
             return ERROR;
         }
     }
 
 Bad dup() was not return descriptor 0.
 
 Is this a dup(3)'s bug?
 (or imcompatible change?)
 
 Workaround:
   mgetty use dup2(3) instead of use dup(3).
 
   dup2(fd, 0)
   .
   .
   dup2(0, 1)
   .
   .
   dup2(0, 2)
   .
   .