gl/getpass.c

   1 /* Copyright (C) 1992-2001, 2003-2007, 2009-2012 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, see <http://www.gnu.org/licenses/>.  */
  17
  18 #ifndef _LIBC
  19 # include <config.h>
  20 #endif
  21
  22 #include "getpass.h"
  23
  24 #include <stdio.h>
  25
  26 #if !((defined _WIN32 || defined __WIN32__) && !defined __CYGWIN__)
  27
  28 # include <stdbool.h>
  29
  30 # if HAVE_DECL___FSETLOCKING && HAVE___FSETLOCKING
  31 #  if HAVE_STDIO_EXT_H
  32 #   include <stdio_ext.h>
  33 #  endif
  34 # else
  35 #  define __fsetlocking(stream, type)    /* empty */
  36 # endif
  37
  38 # if HAVE_TERMIOS_H
  39 #  include <termios.h>
  40 # endif
  41
  42 # if USE_UNLOCKED_IO
  43 #  include "unlocked-io.h"
  44 # else
  45 #  if !HAVE_DECL_FFLUSH_UNLOCKED
  46 #   undef fflush_unlocked
  47 #   define fflush_unlocked(x) fflush (x)
  48 #  endif
  49 #  if !HAVE_DECL_FLOCKFILE
  50 #   undef flockfile
  51 #   define flockfile(x) ((void) 0)
  52 #  endif
  53 #  if !HAVE_DECL_FUNLOCKFILE
  54 #   undef funlockfile
  55 #   define funlockfile(x) ((void) 0)
  56 #  endif
  57 #  if !HAVE_DECL_FPUTS_UNLOCKED
  58 #   undef fputs_unlocked
  59 #   define fputs_unlocked(str,stream) fputs (str, stream)
  60 #  endif
  61 #  if !HAVE_DECL_PUTC_UNLOCKED
  62 #   undef putc_unlocked
  63 #   define putc_unlocked(c,stream) putc (c, stream)
  64 #  endif
  65 # endif
  66
  67 /* It is desirable to use this bit on systems that have it.
  68    The only bit of terminal state we want to twiddle is echoing, which is
  69    done in software; there is no need to change the state of the terminal
  70    hardware.  */
  71
  72 # ifndef TCSASOFT
  73 #  define TCSASOFT 0
  74 # endif
  75
  76 static void
  77 call_fclose (void *arg)
  78 {
  79   if (arg != NULL)
  80     fclose (arg);
  81 }
  82
  83 char *
  84 getpass (const char *prompt)
  85 {
  86   FILE *tty;
  87   FILE *in, *out;
  88   struct termios s, t;
  89   bool tty_changed = false;
  90   static char *buf;
  91   static size_t bufsize;
  92   ssize_t nread;
  93
  94   /* Try to write to and read from the terminal if we can.
  95      If we can't open the terminal, use stderr and stdin.  */
  96
  97   tty = fopen ("/dev/tty", "w+");
  98   if (tty == NULL)
  99     {
 100       in = stdin;
 101       out = stderr;
 102     }
 103   else
 104     {
 105       /* We do the locking ourselves.  */
 106       __fsetlocking (tty, FSETLOCKING_BYCALLER);
 107
 108       out = in = tty;
 109     }
 110
 111   flockfile (out);
 112
 113   /* Turn echoing off if it is on now.  */
 114 # if HAVE_TCGETATTR
 115   if (tcgetattr (fileno (in), &t) == 0)
 116     {
 117       /* Save the old one. */
 118       s = t;
 119       /* Tricky, tricky. */
 120       t.c_lflag &= ~(ECHO | ISIG);
 121       tty_changed = (tcsetattr (fileno (in), TCSAFLUSH | TCSASOFT, &t) == 0);
 122     }
 123 # endif
 124
 125   /* Write the prompt.  */
 126   fputs_unlocked (prompt, out);
 127   fflush_unlocked (out);
 128
 129   /* Read the password.  */
 130   nread = getline (&buf, &bufsize, in);
 131
 132   /* According to the C standard, input may not be followed by output
 133      on the same stream without an intervening call to a file
 134      positioning function.  Suppose in == out; then without this fseek
 135      call, on Solaris, HP-UX, AIX, OSF/1, the previous input gets
 136      echoed, whereas on IRIX, the following newline is not output as
 137      it should be.  POSIX imposes similar restrictions if fileno (in)
 138      == fileno (out).  The POSIX restrictions are tricky and change
 139      from POSIX version to POSIX version, so play it safe and invoke
 140      fseek even if in != out.  */
 141   fseeko (out, 0, SEEK_CUR);
 142
 143   if (buf != NULL)
 144     {
 145       if (nread < 0)
 146         buf[0] = '\0';
 147       else if (buf[nread - 1] == '\n')
 148         {
 149           /* Remove the newline.  */
 150           buf[nread - 1] = '\0';
 151           if (tty_changed)
 152             {
 153               /* Write the newline that was not echoed.  */
 154               putc_unlocked ('\n', out);
 155             }
 156         }
 157     }
 158
 159   /* Restore the original setting.  */
 160 # if HAVE_TCSETATTR
 161   if (tty_changed)
 162     tcsetattr (fileno (in), TCSAFLUSH | TCSASOFT, &s);
 163 # endif
 164
 165   funlockfile (out);
 166
 167   call_fclose (tty);
 168
 169   return buf;
 170 }
 171
 172 #else /* W32 native */
 173
 174 /* Windows implementation by Martin Lambers <marlam@marlam.de>,
 175    improved by Simon Josefsson. */
 176
 177 /* For PASS_MAX. */
 178 # include <limits.h>
 179 /* For _getch(). */
 180 # include <conio.h>
 181 /* For strdup(). */
 182 # include <string.h>
 183
 184 # ifndef PASS_MAX
 185 #  define PASS_MAX 512
 186 # endif
 187
 188 char *
 189 getpass (const char *prompt)
 190 {
 191   char getpassbuf[PASS_MAX + 1];
 192   size_t i = 0;
 193   int c;
 194
 195   if (prompt)
 196     {
 197       fputs (prompt, stderr);
 198       fflush (stderr);
 199     }
 200
 201   for (;;)
 202     {
 203       c = _getch ();
 204       if (c == '\r')
 205         {
 206           getpassbuf[i] = '\0';
 207           break;
 208         }
 209       else if (i < PASS_MAX)
 210         {
 211           getpassbuf[i++] = c;
 212         }
 213
 214       if (i >= PASS_MAX)
 215         {
 216           getpassbuf[i] = '\0';
 217           break;
 218         }
 219     }
 220
 221   if (prompt)
 222     {
 223       fputs ("\r\n", stderr);
 224       fflush (stderr);
 225     }
 226
 227   return strdup (getpassbuf);
 228 }
 229 #endif