BSD 4_1c_2 release

[unix-history] / usr / src / lib / libc / gen / nttyname.c

/* @(#)ttyname.c        4.1 (Berkeley) 12/21/80 */
/*
* ttyname(f): return "/dev/ttyXX" which the the name of the
* tty belonging to file f.
*  NULL if it is not a tty
*/

#define NULL    0
#include <sys/types.h>
#include <sys/ndir.h>
#include <sys/stat.h>

static  char    dev[]   = "/dev/";
char    *strcpy();
char    *strcat();

char *
ttyname(f)
{
       struct stat fsb;
       struct stat tsb;
       register struct direct *db;
       register DIR *df;
       static char rbuf[32];

       if (isatty(f)==0)
               return(NULL);
       if (fstat(f, &fsb) < 0)
               return(NULL);
       if ((fsb.st_mode&S_IFMT) != S_IFCHR)
               return(NULL);
       if ((df = opendir(dev)) == NULL)
               return(NULL);
       while ((db = readdir(df)) != NULL) {
               if (db->d_ino != fsb.st_ino)
                       continue;
               strcpy(rbuf, dev);
               strcat(rbuf, db->d_name);
               if (stat(rbuf, &tsb) < 0)
                       continue;
               if (tsb.st_dev == fsb.st_dev && tsb.st_ino == fsb.st_ino) {
                       closedir(df);
                       return(rbuf);
               }
       }
       closedir(df);
       return(NULL);
}