gl/getpass.c

   1 /* Copyright (C) 1992-2001, 2003-2007, 2009-2010 Free Software Foundation, Inc.
   2
   3    This file is part of the GNU C Library.
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3, or (at your option)
   8    any later version.
   9
  10    This program is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License along
  16    with this program; if not, write to the Free Software Foundation,
  17    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  18
  19 #ifndef _LIBC
  20 # include <config.h>
  21 #endif
  22
  23 #include "getpass.h"
  24
  25 #include <stdio.h>
  26
  27 #if !((defined _WIN32 || defined __WIN32__) && !defined __CYGWIN__)
  28
  29 #include <stdbool.h>
  30
  31 #if HAVE_DECL___FSETLOCKING && HAVE___FSETLOCKING
  32 # if HAVE_STDIO_EXT_H
  33 #  include <stdio_ext.h>
  34 # endif
  35 #else
  36 # define __fsetlocking(stream, type)    /* empty */
  37 #endif
  38
  39 #if HAVE_TERMIOS_H
  40 # include <termios.h>
  41 #endif
  42
  43 #if USE_UNLOCKED_IO
  44 # include "unlocked-io.h"
  45 #else
  46 # if !HAVE_DECL_FFLUSH_UNLOCKED
  47 #  undef fflush_unlocked
  48 #  define fflush_unlocked(x) fflush (x)
  49 # endif
  50 # if !HAVE_DECL_FLOCKFILE
  51 #  undef flockfile
  52 #  define flockfile(x) ((void) 0)
  53 # endif
  54 # if !HAVE_DECL_FUNLOCKFILE
  55 #  undef funlockfile
  56 #  define funlockfile(x) ((void) 0)
  57 # endif
  58 # if !HAVE_DECL_FPUTS_UNLOCKED
  59 #  undef fputs_unlocked
  60 #  define fputs_unlocked(str,stream) fputs (str, stream)
  61 # endif
  62 # if !HAVE_DECL_PUTC_UNLOCKED
  63 #  undef putc_unlocked
  64 #  define putc_unlocked(c,stream) putc (c, stream)
  65 # endif
  66 #endif
  67
  68 /* It is desirable to use this bit on systems that have it.
  69    The only bit of terminal state we want to twiddle is echoing, which is
  70    done in software; there is no need to change the state of the terminal
  71    hardware.  */
  72
  73 #ifndef TCSASOFT
  74 # define TCSASOFT 0
  75 #endif
  76
  77 static void
  78 call_fclose (void *arg)
  79 {
  80   if (arg != NULL)
  81     fclose (arg);
  82 }
  83
  84 char *
  85 getpass (const char *prompt)
  86 {
  87   FILE *tty;
  88   FILE *in, *out;
  89   struct termios s, t;
  90   bool tty_changed = false;
  91   static char *buf;
  92   static size_t bufsize;
  93   ssize_t nread;
  94
  95   /* Try to write to and read from the terminal if we can.
  96      If we can't open the terminal, use stderr and stdin.  */
  97
  98   tty = fopen ("/dev/tty", "w+");
  99   if (tty == NULL)
 100     {
 101       in = stdin;
 102       out = stderr;
 103     }
 104   else
 105     {
 106       /* We do the locking ourselves.  */
 107       __fsetlocking (tty, FSETLOCKING_BYCALLER);
 108
 109       out = in = tty;
 110     }
 111
 112   flockfile (out);
 113
 114   /* Turn echoing off if it is on now.  */
 115 #if HAVE_TCGETATTR
 116   if (tcgetattr (fileno (in), &t) == 0)
 117     {
 118       /* Save the old one. */
 119       s = t;
 120       /* Tricky, tricky. */
 121       t.c_lflag &= ~(ECHO | ISIG);
 122       tty_changed = (tcsetattr (fileno (in), TCSAFLUSH | TCSASOFT, &t) == 0);
 123     }
 124 #endif
 125
 126   /* Write the prompt.  */
 127   fputs_unlocked (prompt, out);
 128   fflush_unlocked (out);
 129
 130   /* Read the password.  */
 131   nread = getline (&buf, &bufsize, in);
 132
 133   /* According to the C standard, input may not be followed by output
 134      on the same stream without an intervening call to a file
 135      positioning function.  Suppose in == out; then without this fseek
 136      call, on Solaris, HP-UX, AIX, OSF/1, the previous input gets
 137      echoed, whereas on IRIX, the following newline is not output as
 138      it should be.  POSIX imposes similar restrictions if fileno (in)
 139      == fileno (out).  The POSIX restrictions are tricky and change
 140      from POSIX version to POSIX version, so play it safe and invoke
 141      fseek even if in != out.  */
 142   fseeko (out, 0, SEEK_CUR);
 143
 144   if (buf != NULL)
 145     {
 146       if (nread < 0)
 147         buf[0] = '\0';
 148       else if (buf[nread - 1] == '\n')
 149         {
 150           /* Remove the newline.  */
 151           buf[nread - 1] = '\0';
 152           if (tty_changed)
 153             {
 154               /* Write the newline that was not echoed.  */
 155               putc_unlocked ('\n', out);
 156             }
 157         }
 158     }
 159
 160   /* Restore the original setting.  */
 161 #if HAVE_TCSETATTR
 162   if (tty_changed)
 163     tcsetattr (fileno (in), TCSAFLUSH | TCSASOFT, &s);
 164 #endif
 165
 166   funlockfile (out);
 167
 168   call_fclose (tty);
 169
 170   return buf;
 171 }
 172
 173 #else /* W32 native */
 174
 175 /* Windows implementation by Martin Lambers <marlam@marlam.de>,
 176    improved by Simon Josefsson. */
 177
 178 /* For PASS_MAX. */
 179 #include <limits.h>
 180 /* For _getch(). */
 181 #include <conio.h>
 182 /* For strdup(). */
 183 #include <string.h>
 184
 185 #ifndef PASS_MAX
 186 # define PASS_MAX 512
 187 #endif
 188
 189 char *
 190 getpass (const char *prompt)
 191 {
 192   char getpassbuf[PASS_MAX + 1];
 193   size_t i = 0;
 194   int c;
 195
 196   if (prompt)
 197     {
 198       fputs (prompt, stderr);
 199       fflush (stderr);
 200     }
 201
 202   for (;;)
 203     {
 204       c = _getch ();
 205       if (c == '\r')
 206         {
 207           getpassbuf[i] = '\0';
 208           break;
 209         }
 210       else if (i < PASS_MAX)
 211         {
 212           getpassbuf[i++] = c;
 213         }
 214
 215       if (i >= PASS_MAX)
 216         {
 217           getpassbuf[i] = '\0';
 218           break;
 219         }
 220     }
 221
 222   if (prompt)
 223     {
 224       fputs ("\r\n", stderr);
 225       fflush (stderr);
 226     }
 227
 228   return strdup (getpassbuf);
 229 }
 230 #endif