getpass.c 3.2 KB

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  1. /* Copyright (C) 1992-1999,2001,2003,2004,2005 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 Lesser General Public
  5. License as published by the Free Software Foundation; either
  6. version 2.1 of the 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. Lesser General Public License for more details.
  11. You should have received a copy of the GNU Lesser General Public
  12. License along with the GNU C Library; if not, write to the Free
  13. Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  14. 02111-1307 USA. */
  15. #include <stdio.h>
  16. #include <string.h>
  17. #include <termios.h>
  18. #include <unistd.h>
  19. #if defined __USE_BSD || (defined __USE_XOPEN && !defined __USE_XOPEN2K)
  20. /* Experimentally off - libc_hidden_proto(strlen) */
  21. libc_hidden_proto(tcsetattr)
  22. libc_hidden_proto(tcgetattr)
  23. libc_hidden_proto(setvbuf)
  24. libc_hidden_proto(fopen)
  25. libc_hidden_proto(fclose)
  26. libc_hidden_proto(fileno)
  27. libc_hidden_proto(fflush)
  28. libc_hidden_proto(fgets)
  29. libc_hidden_proto(fputs)
  30. libc_hidden_proto(fputc)
  31. libc_hidden_proto(putc)
  32. libc_hidden_proto(__fputc_unlocked)
  33. /* It is desirable to use this bit on systems that have it.
  34. The only bit of terminal state we want to twiddle is echoing, which is
  35. done in software; there is no need to change the state of the terminal
  36. hardware. */
  37. #ifndef TCSASOFT
  38. #define TCSASOFT 0
  39. #endif
  40. #define PWD_BUFFER_SIZE 256
  41. char * getpass (const char *prompt)
  42. {
  43. FILE *in, *out;
  44. struct termios s, t;
  45. int tty_changed;
  46. static char buf[PWD_BUFFER_SIZE];
  47. int 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. */
  50. in = fopen ("/dev/tty", "r+");
  51. if (in == NULL)
  52. {
  53. in = stdin;
  54. out = stderr;
  55. }
  56. else
  57. out = in;
  58. /* Turn echoing off if it is on now. */
  59. if (tcgetattr (fileno (in), &t) == 0)
  60. {
  61. /* Save the old one. */
  62. s = t;
  63. /* Tricky, tricky. */
  64. t.c_lflag &= ~(ECHO|ISIG);
  65. tty_changed = (tcsetattr (fileno (in), TCSAFLUSH|TCSASOFT, &t) == 0);
  66. if (in != stdin) {
  67. /* Disable buffering for read/write FILE to prevent problems with
  68. * fseek and buffering for read/write auto-transitioning. */
  69. setvbuf(in, NULL, _IONBF, 0);
  70. }
  71. }
  72. else
  73. tty_changed = 0;
  74. /* Write the prompt. */
  75. fputs(prompt, out);
  76. fflush(out);
  77. /* Read the password. */
  78. fgets (buf, PWD_BUFFER_SIZE-1, in);
  79. if (buf != NULL)
  80. {
  81. nread = strlen(buf);
  82. if (nread < 0)
  83. buf[0] = '\0';
  84. else if (buf[nread - 1] == '\n')
  85. {
  86. /* Remove the newline. */
  87. buf[nread - 1] = '\0';
  88. if (tty_changed)
  89. /* Write the newline that was not echoed. */
  90. putc('\n', out);
  91. }
  92. }
  93. /* Restore the original setting. */
  94. if (tty_changed) {
  95. (void) tcsetattr (fileno (in), TCSAFLUSH|TCSASOFT, &s);
  96. }
  97. if (in != stdin)
  98. /* We opened the terminal; now close it. */
  99. fclose (in);
  100. return buf;
  101. }
  102. #endif