contrib/cvs/lib/getpass.c

   1 /* Copyright (C) 1992,93,94,95,96,97,98,99,2000, 2001 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License along
  15    with this program; if not, write to the Free Software Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  17
  18 #if HAVE_CONFIG_H
  19 # include <config.h>
  20 #endif
  21
  22 #include <stdio.h>
  23 #ifndef SEEK_CUR
  24 #define SEEK_CUR 1
  25 #endif
  26 #include <termios.h>
  27 #include <unistd.h>
  28 #include "getline.h"
  29
  30 /* It is desirable to use this bit on systems that have it.
  31    The only bit of terminal state we want to twiddle is echoing, which is
  32    done in software; there is no need to change the state of the terminal
  33    hardware.  */
  34
  35 #ifndef TCSASOFT
  36 # define TCSASOFT 0
  37 #endif
  38
  39 char *
  40 #if __STDC__
  41 getpass (const char *prompt)
  42 #else
  43 getpass (prompt)
  44      const char *prompt;
  45 #endif
  46 {
  47   FILE *in, *out;
  48   struct termios s, t;
  49   int tty_changed;
  50   static char *buf;
  51   static size_t bufsize;
  52   ssize_t nread;
  53
  54   /* Try to write to and read from the terminal if we can.
  55      If we can't open the terminal, use stderr and stdin.  */
  56
  57   in = fopen ("/dev/tty", "w+");
  58   if (in == NULL)
  59     {
  60       in = stdin;
  61       out = stderr;
  62     }
  63   else
  64     out = in;
  65
  66   /* Turn echoing off if it is on now.  */
  67
  68   if (tcgetattr (fileno (in), &t) == 0)
  69     {
  70       /* Save the old one. */
  71       s = t;
  72       /* Tricky, tricky. */
  73       t.c_lflag &= ~(ECHO|ISIG);
  74       tty_changed = (tcsetattr (fileno (in), TCSAFLUSH|TCSASOFT, &t) == 0);
  75     }
  76   else
  77     tty_changed = 0;
  78
  79   /* Write the prompt.  */
  80   fputs (prompt, out);
  81   fflush (out);
  82
  83   /* Read the password.  */
  84   nread = getline (&buf, &bufsize, in);
  85   if (buf != NULL)
  86     {
  87       if (nread < 0)
  88         buf[0] = '\0';
  89       else if (buf[nread - 1] == '\n')
  90         {
  91           /* Remove the newline.  */
  92           buf[nread - 1] = '\0';
  93           if (tty_changed)
  94             {
  95               /* Write the newline that was not echoed.  */
  96               if (out == in) fseek (out, 0, SEEK_CUR);
  97               putc ('\n', out);
  98             }
  99         }
 100     }
 101
 102   /* Restore the original setting.  */
 103   if (tty_changed)
 104     (void) tcsetattr (fileno (in), TCSAFLUSH|TCSASOFT, &s);
 105
 106   if (in != stdin)
 107     /* We opened the terminal; now close it.  */
 108     fclose (in);
 109
 110   return buf;
 111 }