Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!cornell!uw-beaver!ssc-vax!uvicctr!tholm
From: tholm@uvicctr.UUCP (Terrence W. Holm)
Newsgroups: comp.os.minix
Subject: ttyname(3)
Message-ID: <477@uvicctr.UUCP>
Date: 26 Aug 88 00:11:07 GMT
Reply-To: tholm@uvicctr.UUCP (Terrence W. Holm)
Organization: University of Victoria, Victoria B.C. Canada
Lines: 117

EFTH MINIX report #33  - August 1988 -  ttyname(3)


Ttyname(3) seems to be missing in the distribution of
MINIX 1.3. I can not find the original posting [PH?],
and Dr. Tanenbaum doesn't have it either - so, here
is what I currently use.


----------------------------------------------------------
echo x - ttyname.3
gres '^X' '' > ttyname.3 << '/'
XSUBROUTINES
X    ttyname(3)   	- look up the filename of a terminal device
X
XINVOCATION
X    char  *ttyname( desc )
X      int  desc;
X
XEXPLANATION
X    The argument <desc> must be a file descriptor for a character
X    device. This routine returns a pointer to the filename within
X    "/dev" which is associated with that file descriptor. For
X    example, the command tty(1) is almost as simple as
X    "puts( ttyname(0) )".
X
X    The string space for the filename is static storage within
X    ttyname(3), it is overwritten by subsequent calls.
X
XRESULTS
X    NULL : No filename found in /dev.
X    o/w  : Pointer to string name of device.
X
XFILES
X    /dev/*
X
XREFERENCES
X    tty(1), fstat(2), isatty(2), ctermid(3)
/
echo x - ttyname.c
gres '^X' '' > ttyname.c << '/'
X/*  ttyname(3)
X */
X
X#include <sys/types.h>
X#include <sys/dir.h>
X#include <sys/stat.h>
X
X#define  NULL 	(char *) 0
X#define  DEV	"/dev/"
X
Xstatic char file_name[40];
X
X
Xchar *ttyname( tty_file_desc )
X  int tty_file_desc;
X
X  {
X  int dev_dir_desc;
X  struct direct dir_entry;
X  struct stat tty_stat;
X  struct stat dev_stat;
X
X  /*  Make sure the supplied file descriptor is for a terminal  */
X
X  if ( fstat(tty_file_desc, &tty_stat) < 0 )
X	return( NULL );
X
X  if ( (tty_stat.st_mode & S_IFMT) != S_IFCHR )
X	return( NULL );
X
X
X  /*  Open /dev for reading  */
X
X  if ( (dev_dir_desc = open(DEV,0)) < 0 )
X	return( NULL );
X
X  while ( read(dev_dir_desc, (char *) &dir_entry, sizeof (struct direct)) > 0 )
X	{
X	/*  Find an entry in /dev with the same inode number  */
X
X	if ( tty_stat.st_ino != dir_entry.d_ino )
X		continue;
X
X	/*  Put the name of the device in static storage  */
X
X	strcpy( file_name, DEV );
X	strncat( file_name, dir_entry.d_name, sizeof (dir_entry.d_name) );
X
X	/*  Be absolutely certain the inodes match  */
X
X  	if ( stat(file_name, &dev_stat) < 0 )
X		continue;
X
X  	if ( (dev_stat.st_mode & S_IFMT) != S_IFCHR )
X		continue;
X
X  	if ( tty_stat.st_ino  == dev_stat.st_ino  &&
X	     tty_stat.st_dev  == dev_stat.st_dev  &&
X	     tty_stat.st_rdev == dev_stat.st_rdev )
X		{
X		close( dev_dir_desc );
X		return( file_name );
X		}
X	}
X
X  close( dev_dir_desc );
X  return( NULL );
X  }
/
----------------------------------------------------------

		Edwin L. Froese
		  uw-beaver!ubc-cs!mprg!handel!froese

		Terrence W. Holm
		  uw-beaver!uvicctr!tholm