summaryrefslogtreecommitdiff
path: root/lib/getpass.c
blob: 426f47cade01404f2f05a3b6b9986d3a1eeab9ea (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
/* Copyright (C) 1992-2001, 2003-2007, 2009-2020 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License along
   with this program; if not, see <https://www.gnu.org/licenses/>.  */

#ifndef _LIBC
/* Don't use __attribute__ __nonnull__ in this compilation unit.  Otherwise gcc
   warns for the null checks on 'prompt' below.  */
# define _GL_ARG_NONNULL(params)
# include <config.h>
#endif

#include "getpass.h"

#include <stdio.h>

#if !(defined _WIN32 && !defined __CYGWIN__)

# include <stdbool.h>

# if HAVE_DECL___FSETLOCKING && HAVE___FSETLOCKING
#  if HAVE_STDIO_EXT_H
#   include <stdio_ext.h>
#  endif
# else
#  define __fsetlocking(stream, type)    /* empty */
# endif

# if HAVE_TERMIOS_H
#  include <termios.h>
# endif

# if USE_UNLOCKED_IO
#  include "unlocked-io.h"
# else
#  if !HAVE_DECL_FFLUSH_UNLOCKED
#   undef fflush_unlocked
#   define fflush_unlocked(x) fflush (x)
#  endif
#  if !HAVE_DECL_FLOCKFILE
#   undef flockfile
#   define flockfile(x) ((void) 0)
#  endif
#  if !HAVE_DECL_FUNLOCKFILE
#   undef funlockfile
#   define funlockfile(x) ((void) 0)
#  endif
#  if !HAVE_DECL_FPUTS_UNLOCKED
#   undef fputs_unlocked
#   define fputs_unlocked(str,stream) fputs (str, stream)
#  endif
#  if !HAVE_DECL_PUTC_UNLOCKED
#   undef putc_unlocked
#   define putc_unlocked(c,stream) putc (c, stream)
#  endif
# endif

/* It is desirable to use this bit on systems that have it.
   The only bit of terminal state we want to twiddle is echoing, which is
   done in software; there is no need to change the state of the terminal
   hardware.  */

# ifndef TCSASOFT
#  define TCSASOFT 0
# endif

static void
call_fclose (void *arg)
{
  if (arg != NULL)
    fclose (arg);
}

char *
getpass (const char *prompt)
{
  FILE *tty;
  FILE *in, *out;
# if HAVE_TCGETATTR
  struct termios s, t;
# endif
  bool tty_changed = false;
  static char *buf;
  static size_t bufsize;
  ssize_t nread;

  /* Try to write to and read from the terminal if we can.
     If we can't open the terminal, use stderr and stdin.  */

  tty = fopen ("/dev/tty", "w+e");
  if (tty == NULL)
    {
      in = stdin;
      out = stderr;
    }
  else
    {
      /* We do the locking ourselves.  */
      __fsetlocking (tty, FSETLOCKING_BYCALLER);

      out = in = tty;
    }

  flockfile (out);

  /* Turn echoing off if it is on now.  */
# if HAVE_TCGETATTR
  if (tcgetattr (fileno (in), &t) == 0)
    {
      /* Save the old one. */
      s = t;
      /* Tricky, tricky. */
      t.c_lflag &= ~(ECHO | ISIG);
      tty_changed = (tcsetattr (fileno (in), TCSAFLUSH | TCSASOFT, &t) == 0);
    }
# endif

  if (prompt)
    {
      /* Write the prompt.  */
      fputs_unlocked (prompt, out);
      fflush_unlocked (out);
    }

  /* Read the password.  */
  nread = getline (&buf, &bufsize, in);

  /* According to the C standard, input may not be followed by output
     on the same stream without an intervening call to a file
     positioning function.  Suppose in == out; then without this fseek
     call, on Solaris, HP-UX, AIX, OSF/1, the previous input gets
     echoed, whereas on IRIX, the following newline is not output as
     it should be.  POSIX imposes similar restrictions if fileno (in)
     == fileno (out).  The POSIX restrictions are tricky and change
     from POSIX version to POSIX version, so play it safe and invoke
     fseek even if in != out.  */
  fseeko (out, 0, SEEK_CUR);

  if (buf != NULL)
    {
      if (nread < 0)
        buf[0] = '\0';
      else if (buf[nread - 1] == '\n')
        {
          /* Remove the newline.  */
          buf[nread - 1] = '\0';
          if (tty_changed)
            {
              /* Write the newline that was not echoed.  */
              putc_unlocked ('\n', out);
            }
        }
    }

  /* Restore the original setting.  */
# if HAVE_TCSETATTR
  if (tty_changed)
    tcsetattr (fileno (in), TCSAFLUSH | TCSASOFT, &s);
# endif

  funlockfile (out);

  call_fclose (tty);

  return buf;
}

#else /* W32 native */

/* Windows implementation by Martin Lambers <marlam@marlam.de>,
   improved by Simon Josefsson. */

/* For PASS_MAX. */
# include <limits.h>
/* For _getch(). */
# include <conio.h>
/* For strdup(). */
# include <string.h>

# ifndef PASS_MAX
#  define PASS_MAX 512
# endif

char *
getpass (const char *prompt)
{
  char getpassbuf[PASS_MAX + 1];
  size_t i = 0;
  int c;

  if (prompt)
    {
      fputs (prompt, stderr);
      fflush (stderr);
    }

  for (;;)
    {
      c = _getch ();
      if (c == '\r')
        {
          getpassbuf[i] = '\0';
          break;
        }
      else if (i < PASS_MAX)
        {
          getpassbuf[i++] = c;
        }

      if (i >= PASS_MAX)
        {
          getpassbuf[i] = '\0';
          break;
        }
    }

  if (prompt)
    {
      fputs ("\r\n", stderr);
      fflush (stderr);
    }

  return strdup (getpassbuf);
}
#endif