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[glibc.git] / misc / getpass.c
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1 /* Copyright (C) 1992,93,94,95,96,97,98,99 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Library General Public License as
6 published by the Free Software Foundation; either version 2 of the
7 License, or (at your option) any later version.
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 Library General Public License for more details.
14 You should have received a copy of the GNU Library General Public
15 License along with the GNU C Library; see the file COPYING.LIB. If not,
16 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
17 Boston, MA 02111-1307, USA. */
19 #include <stdio.h>
20 #include <termios.h>
21 #include <unistd.h>
23 #ifdef USE_IN_LIBIO
24 # define flockfile(s) _IO_flockfile (s)
25 # define funlockfile(s) _IO_funlockfile (s)
26 #endif
28 /* It is desirable to use this bit on systems that have it.
29 The only bit of terminal state we want to twiddle is echoing, which is
30 done in software; there is no need to change the state of the terminal
31 hardware. */
33 #ifndef TCSASOFT
34 #define TCSASOFT 0
35 #endif
37 char *
38 getpass (prompt)
39 const char *prompt;
41 FILE *in, *out;
42 struct termios s, t;
43 int tty_changed;
44 static char *buf;
45 static size_t bufsize;
46 ssize_t nread;
48 /* Try to write to and read from the terminal if we can.
49 If we can't open the terminal, use stderr and stdin. */
51 in = fopen ("/dev/tty", "w+");
52 if (in == NULL)
54 in = stdin;
55 out = stderr;
57 else
58 out = in;
60 flockfile (out);
62 /* Turn echoing off if it is on now. */
64 if (__tcgetattr (fileno (in), &t) == 0)
66 /* Save the old one. */
67 s = t;
68 /* Tricky, tricky. */
69 t.c_lflag &= ~(ECHO|ISIG);
70 tty_changed = (tcsetattr (fileno (in), TCSAFLUSH|TCSASOFT, &t) == 0);
72 else
73 tty_changed = 0;
75 /* Write the prompt. */
76 fputs_unlocked (prompt, out);
77 fflush_unlocked (out);
79 /* Read the password. */
80 nread = __getline (&buf, &bufsize, in);
81 if (buf != NULL)
83 if (nread < 0)
84 buf[0] = '\0';
85 else if (buf[nread - 1] == '\n')
87 /* Remove the newline. */
88 buf[nread - 1] = '\0';
89 if (tty_changed)
90 /* Write the newline that was not echoed. */
91 putc_unlocked ('\n', out);
95 /* Restore the original setting. */
96 if (tty_changed)
97 (void) tcsetattr (fileno (in), TCSAFLUSH|TCSASOFT, &s);
99 funlockfile (out);
101 if (in != stdin)
102 /* We opened the terminal; now close it. */
103 fclose (in);
105 return buf;