minix/commands/telnetd/pty.c

   1 /*
   2  * TNET         A server program for MINIX which implements the TCP/IP
   3  *              suite of networking protocols.  It is based on the
   4  *              TCP/IP code written by Phil Karn et al, as found in
   5  *              his NET package for Packet Radio communications.
   6  *
   7  *              Handle the allocation of a PTY.
   8  *
   9  * Author:      Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org>
  10  */
  11 #include <sys/types.h>
  12 #include <errno.h>
  13 #include <fcntl.h>
  14 #include <stdlib.h>
  15 #include <unistd.h>
  16 #include <string.h>
  17 #include <stdio.h>
  18 #include "telnetd.h"
  19
  20
  21 #define DEV_DIR         "/dev"
  22
  23 /*
  24  * Allocate a PTY, by trying to open one repeatedly,
  25  * until all PTY channels are done.  If at that point
  26  * no PTY is found, go into panic mode :-(
  27  */
  28 int get_pty(pty_fdp, tty_namep)
  29 int *pty_fdp;
  30 char **tty_namep;
  31 {
  32   char buff[128], temp[128];
  33   register int i, j;
  34   int pty_fd;
  35   static char tty_name[128];
  36
  37   for(i = 'p'; i < 'w'; i++) {
  38         j = 0;
  39         do {
  40                 sprintf(buff, "%s/pty%c%c",
  41                         DEV_DIR, i, (j < 10) ? j + '0' : j + 'a' - 10);
  42
  43                 if (opt_d == 1) {
  44                         (void) write(2, "Testing: ", 9);
  45                         (void) write(2, buff, strlen(buff));
  46                         (void) write(2, "...: ", 5);
  47                 }
  48
  49                 pty_fd = open(buff, O_RDWR);
  50                 if (opt_d == 1) {
  51                         if (pty_fd < 0) sprintf(temp, "error %d\r\n", errno);
  52                           else sprintf(temp, "OK\r\n");
  53                         (void) write(2, temp, strlen(temp));
  54                 }
  55
  56                 if (pty_fd >= 0) break;
  57
  58                 j++;
  59                 if (j == 16) break;
  60         } while(1);
  61
  62         /* Did we find one? */
  63         if (j < 16) break;
  64   }
  65   if (pty_fd < 0) return(-1);
  66
  67   if (opt_d == 1) {
  68         sprintf(temp, "File %s, desc %d\n", buff, pty_fd);
  69         (void) write(1, temp, strlen(temp));
  70   }
  71
  72   sprintf(tty_name, "%s/tty%c%c", DEV_DIR,
  73                                         i, (j < 10) ? j + '0' : j + 'a' - 10);
  74
  75   *pty_fdp = pty_fd;
  76   *tty_namep = tty_name;
  77   return(0);
  78 }