1/* Copyright (C) 1992-2023 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library 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 GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18#include <stdio.h>
19#include <stdio_ext.h>
20#include <string.h> /* For string function builtin redirect. */
21#include <termios.h>
22#include <unistd.h>
23
24#include <wchar.h>
25#define flockfile(s) _IO_flockfile (s)
26#define funlockfile(s) _IO_funlockfile (s)
27#include <libc-lock.h>
28
29/* It is desirable to use this bit on systems that have it.
30 The only bit of terminal state we want to twiddle is echoing, which is
31 done in software; there is no need to change the state of the terminal
32 hardware. */
33
34#ifndef TCSASOFT
35#define TCSASOFT 0
36#endif
37
38static void
39call_fclose (void *arg)
40{
41 if (arg != NULL)
42 fclose (arg);
43}
44
45char *
46getpass (const char *prompt)
47{
48 FILE *in, *out;
49 struct termios s, t;
50 int tty_changed;
51 static char *buf;
52 static size_t bufsize;
53 ssize_t nread;
54
55 /* Try to write to and read from the terminal if we can.
56 If we can't open the terminal, use stderr and stdin. */
57
58 in = fopen ("/dev/tty", "w+ce");
59 if (in == NULL)
60 {
61 in = stdin;
62 out = stderr;
63 }
64 else
65 {
66 /* We do the locking ourselves. */
67 __fsetlocking (in, FSETLOCKING_BYCALLER);
68
69 out = in;
70 }
71
72 /* Make sure the stream we opened is closed even if the thread is
73 canceled. */
74 __libc_cleanup_push (call_fclose, in == out ? in : NULL);
75
76 flockfile (out);
77
78 /* Turn echoing off if it is on now. */
79
80 if (__tcgetattr (fileno (in), &t) == 0)
81 {
82 /* Save the old one. */
83 s = t;
84 /* Tricky, tricky. */
85 t.c_lflag &= ~(ECHO|ISIG);
86 tty_changed = (tcsetattr (fileno (in), TCSAFLUSH|TCSASOFT, &t) == 0);
87 }
88 else
89 tty_changed = 0;
90
91 /* Write the prompt. */
92 __fxprintf (out, "%s", prompt);
93 __fflush_unlocked (out);
94
95 /* Read the password. */
96 nread = __getline (&buf, &bufsize, in);
97 if (buf != NULL)
98 {
99 if (nread < 0)
100 buf[0] = '\0';
101 else if (buf[nread - 1] == '\n')
102 {
103 /* Remove the newline. */
104 buf[nread - 1] = '\0';
105 if (tty_changed)
106 /* Write the newline that was not echoed. */
107 __fxprintf (out, "\n");
108 }
109 }
110
111 /* Restore the original setting. */
112 if (tty_changed)
113 (void) tcsetattr (fileno (in), TCSAFLUSH|TCSASOFT, &s);
114
115 funlockfile (out);
116
117 __libc_cleanup_pop (0);
118
119 if (in != stdin)
120 /* We opened the terminal; now close it. */
121 fclose (in);
122
123 return buf;
124}
125