getpass.c 2.8 KB

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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.
  3. The GNU C Library is free software; you can redistribute it and/or
  4. modify it under the terms of the GNU Library General Public License as
  5. published by the Free Software Foundation; either version 2 of the
  6. License, or (at your option) any later version.
  7. The GNU C Library is distributed in the hope that it will be useful,
  8. but WITHOUT ANY WARRANTY; without even the implied warranty of
  9. MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  10. Library General Public License for more details.
  11. You should have received a copy of the GNU Library General Public
  12. License along with the GNU C Library; see the file COPYING.LIB. If not,
  13. write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  14. Boston, MA 02111-1307, USA. */
  15. #include <stdio.h>
  16. #include <string.h>
  17. #include <termios.h>
  18. #include <unistd.h>
  19. #include <string.h>
  20. /* It is desirable to use this bit on systems that have it.
  21. The only bit of terminal state we want to twiddle is echoing, which is
  22. done in software; there is no need to change the state of the terminal
  23. hardware. */
  24. #ifndef TCSASOFT
  25. #define TCSASOFT 0
  26. #endif
  27. #define PWD_BUFFER_SIZE 256
  28. char *
  29. getpass (prompt)
  30. const char *prompt;
  31. {
  32. FILE *in, *out;
  33. struct termios s, t;
  34. int tty_changed;
  35. static char buf[PWD_BUFFER_SIZE];
  36. int nread;
  37. /* Try to write to and read from the terminal if we can.
  38. If we can't open the terminal, use stderr and stdin. */
  39. in = fopen ("/dev/tty", "r+");
  40. if (in == NULL)
  41. {
  42. in = stdin;
  43. out = stderr;
  44. }
  45. else
  46. out = in;
  47. /* Turn echoing off if it is on now. */
  48. if (tcgetattr (fileno (in), &t) == 0)
  49. {
  50. /* Save the old one. */
  51. s = t;
  52. /* Tricky, tricky. */
  53. t.c_lflag &= ~(ECHO|ISIG);
  54. tty_changed = (tcsetattr (fileno (in), TCSAFLUSH|TCSASOFT, &t) == 0);
  55. if (in != stdin) {
  56. /* Disable buffering for read/write FILE to prevent problems with
  57. * fseek and buffering for read/write auto-transitioning. */
  58. setvbuf(in, NULL, _IONBF, 0);
  59. }
  60. }
  61. else
  62. tty_changed = 0;
  63. /* Write the prompt. */
  64. fputs(prompt, out);
  65. fflush(out);
  66. /* Read the password. */
  67. fgets (buf, PWD_BUFFER_SIZE-1, in);
  68. if (buf != NULL)
  69. {
  70. nread = strlen(buf);
  71. if (nread < 0)
  72. buf[0] = '\0';
  73. else if (buf[nread - 1] == '\n')
  74. {
  75. /* Remove the newline. */
  76. buf[nread - 1] = '\0';
  77. if (tty_changed)
  78. /* Write the newline that was not echoed. */
  79. putc('\n', out);
  80. }
  81. }
  82. /* Restore the original setting. */
  83. if (tty_changed) {
  84. (void) tcsetattr (fileno (in), TCSAFLUSH|TCSASOFT, &s);
  85. }
  86. if (in != stdin)
  87. /* We opened the terminal; now close it. */
  88. fclose (in);
  89. return buf;
  90. }