gl/getpass.c

   1 /* Copyright (C) 1992-2001, 2003, 2004, 2005, 2006, 2007 Free Software
   2    Foundation, Inc.
   3
   4    This file is part of the GNU C Library.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2, or (at your option)
   9    any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License along
  17    with this program; if not, write to the Free Software Foundation,
  18    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  19
  20 #ifndef _LIBC
  21 # include <config.h>
  22 #endif
  23
  24 #include "getpass.h"
  25
  26 #include <stdio.h>
  27
  28 #if !((defined _WIN32 || defined __WIN32__) && !defined __CYGWIN__)
  29
  30 #include <stdbool.h>
  31
  32 #if HAVE_DECL___FSETLOCKING && HAVE___FSETLOCKING
  33 # if HAVE_STDIO_EXT_H
  34 #  include <stdio_ext.h>
  35 # endif
  36 #else
  37 # define __fsetlocking(stream, type)    /* empty */
  38 #endif
  39
  40 #if HAVE_TERMIOS_H
  41 # include <termios.h>
  42 #endif
  43
  44 #include "getline.h"
  45
  46 #if USE_UNLOCKED_IO
  47 # include "unlocked-io.h"
  48 #else
  49 # if !HAVE_DECL_FFLUSH_UNLOCKED
  50 #  undef fflush_unlocked
  51 #  define fflush_unlocked(x) fflush (x)
  52 # endif
  53 # if !HAVE_DECL_FLOCKFILE
  54 #  undef flockfile
  55 #  define flockfile(x) ((void) 0)
  56 # endif
  57 # if !HAVE_DECL_FUNLOCKFILE
  58 #  undef funlockfile
  59 #  define funlockfile(x) ((void) 0)
  60 # endif
  61 # if !HAVE_DECL_FPUTS_UNLOCKED
  62 #  undef fputs_unlocked
  63 #  define fputs_unlocked(str,stream) fputs (str, stream)
  64 # endif
  65 # if !HAVE_DECL_PUTC_UNLOCKED
  66 #  undef putc_unlocked
  67 #  define putc_unlocked(c,stream) putc (c, stream)
  68 # endif
  69 #endif
  70
  71 /* It is desirable to use this bit on systems that have it.
  72    The only bit of terminal state we want to twiddle is echoing, which is
  73    done in software; there is no need to change the state of the terminal
  74    hardware.  */
  75
  76 #ifndef TCSASOFT
  77 # define TCSASOFT 0
  78 #endif
  79
  80 static void
  81 call_fclose (void *arg)
  82 {
  83   if (arg != NULL)
  84     fclose (arg);
  85 }
  86
  87 char *
  88 getpass (const char *prompt)
  89 {
  90   FILE *tty;
  91   FILE *in, *out;
  92   struct termios s, t;
  93   bool tty_changed = false;
  94   static char *buf;
  95   static size_t bufsize;
  96   ssize_t nread;
  97
  98   /* Try to write to and read from the terminal if we can.
  99      If we can't open the terminal, use stderr and stdin.  */
 100
 101   tty = fopen ("/dev/tty", "w+");
 102   if (tty == NULL)
 103     {
 104       in = stdin;
 105       out = stderr;
 106     }
 107   else
 108     {
 109       /* We do the locking ourselves.  */
 110       __fsetlocking (tty, FSETLOCKING_BYCALLER);
 111
 112       out = in = tty;
 113     }
 114
 115   flockfile (out);
 116
 117   /* Turn echoing off if it is on now.  */
 118 #if HAVE_TCGETATTR
 119   if (tcgetattr (fileno (in), &t) == 0)
 120     {
 121       /* Save the old one. */
 122       s = t;
 123       /* Tricky, tricky. */
 124       t.c_lflag &= ~(ECHO | ISIG);
 125       tty_changed = (tcsetattr (fileno (in), TCSAFLUSH | TCSASOFT, &t) == 0);
 126     }
 127 #endif
 128
 129   /* Write the prompt.  */
 130   fputs_unlocked (prompt, out);
 131   fflush_unlocked (out);
 132
 133   /* Read the password.  */
 134   nread = getline (&buf, &bufsize, in);
 135
 136   /* According to the C standard, input may not be followed by output
 137      on the same stream without an intervening call to a file
 138      positioning function.  Suppose in == out; then without this fseek
 139      call, on Solaris, HP-UX, AIX, OSF/1, the previous input gets
 140      echoed, whereas on IRIX, the following newline is not output as
 141      it should be.  POSIX imposes similar restrictions if fileno (in)
 142      == fileno (out).  The POSIX restrictions are tricky and change
 143      from POSIX version to POSIX version, so play it safe and invoke
 144      fseek even if in != out.  */
 145   fseeko (out, 0, SEEK_CUR);
 146
 147   if (buf != NULL)
 148     {
 149       if (nread < 0)
 150         buf[0] = '\0';
 151       else if (buf[nread - 1] == '\n')
 152         {
 153           /* Remove the newline.  */
 154           buf[nread - 1] = '\0';
 155           if (tty_changed)
 156             {
 157               /* Write the newline that was not echoed.  */
 158               putc_unlocked ('\n', out);
 159             }
 160         }
 161     }
 162
 163   /* Restore the original setting.  */
 164 #if HAVE_TCSETATTR
 165   if (tty_changed)
 166     tcsetattr (fileno (in), TCSAFLUSH | TCSASOFT, &s);
 167 #endif
 168
 169   funlockfile (out);
 170
 171   call_fclose (tty);
 172
 173   return buf;
 174 }
 175
 176 #else /* W32 native */
 177
 178 /* Windows implementation by Martin Lambers <marlam@marlam.de>,
 179    improved by Simon Josefsson. */
 180
 181 /* For PASS_MAX. */
 182 #include <limits.h>
 183 /* For _getch(). */
 184 #include <conio.h>
 185 /* For strdup(). */
 186 #include <string.h>
 187
 188 #ifndef PASS_MAX
 189 # define PASS_MAX 512
 190 #endif
 191
 192 char *
 193 getpass (const char *prompt)
 194 {
 195   char getpassbuf[PASS_MAX + 1];
 196   size_t i = 0;
 197   int c;
 198
 199   if (prompt)
 200     {
 201       fputs (prompt, stderr);
 202       fflush (stderr);
 203     }
 204
 205   for (;;)
 206     {
 207       c = _getch ();
 208       if (c == '\r')
 209         {
 210           getpassbuf[i] = '\0';
 211           break;
 212         }
 213       else if (i < PASS_MAX)
 214         {
 215           getpassbuf[i++] = c;
 216         }
 217
 218       if (i >= PASS_MAX)
 219         {
 220           getpassbuf[i] = '\0';
 221           break;
 222         }
 223     }
 224
 225   if (prompt)
 226     {
 227       fputs ("\r\n", stderr);
 228       fflush (stderr);
 229     }
 230
 231   return strdup (getpassbuf);
 232 }
 233 #endif