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BIO_s_fd.pod 2.7 KB

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  1. =pod
  2. =head1 NAME
  3. BIO_s_fd, BIO_set_fd, BIO_get_fd, BIO_new_fd - file descriptor BIO
  4. =head1 SYNOPSIS
  5. #include <openssl/bio.h>
  6. BIO_METHOD * BIO_s_fd(void);
  7. #define BIO_set_fd(b,fd,c) BIO_int_ctrl(b,BIO_C_SET_FD,c,fd)
  8. #define BIO_get_fd(b,c) BIO_ctrl(b,BIO_C_GET_FD,0,(char *)c)
  9. BIO *BIO_new_fd(int fd, int close_flag);
  10. =head1 DESCRIPTION
  11. BIO_s_fd() returns the file descriptor BIO method. This is a wrapper
  12. round the platforms file descriptor routines such as read() and write().
  13. BIO_read() and BIO_write() read or write the underlying descriptor.
  14. BIO_puts() is supported but BIO_gets() is not.
  15. If the close flag is set then then close() is called on the underlying
  16. file descriptor when the BIO is freed.
  17. BIO_reset() attempts to change the file pointer to the start of file
  18. using lseek(fd, 0, 0).
  19. BIO_seek() sets the file pointer to position B<ofs> from start of file
  20. using lseek(fd, ofs, 0).
  21. BIO_tell() returns the current file position by calling lseek(fd, 0, 1).
  22. BIO_set_fd() sets the file descriptor of BIO B<b> to B<fd> and the close
  23. flag to B<c>.
  24. BIO_get_fd() places the file descriptor in B<c> if it is not NULL, it also
  25. returns the file descriptor. If B<c> is not NULL it should be of type
  26. (int *).
  27. BIO_new_fd() returns a file descriptor BIO using B<fd> and B<close_flag>.
  28. =head1 NOTES
  29. The behaviour of BIO_read() and BIO_write() depends on the behavior of the
  30. platforms read() and write() calls on the descriptor. If the underlying
  31. file descriptor is in a non blocking mode then the BIO will behave in the
  32. manner described in the L<BIO_read(3)|BIO_read(3)> and L<BIO_should_retry(3)|BIO_should_retry(3)>
  33. manual pages.
  34. File descriptor BIOs should not be used for socket I/O. Use socket BIOs
  35. instead.
  36. =head1 RETURN VALUES
  37. BIO_s_fd() returns the file descriptor BIO method.
  38. BIO_reset() returns zero for success and -1 if an error occurred.
  39. BIO_seek() and BIO_tell() return the current file position or -1
  40. is an error occurred. These values reflect the underlying lseek()
  41. behaviour.
  42. BIO_set_fd() always returns 1.
  43. BIO_get_fd() returns the file descriptor or -1 if the BIO has not
  44. been initialized.
  45. BIO_new_fd() returns the newly allocated BIO or NULL is an error
  46. occurred.
  47. =head1 EXAMPLE
  48. This is a file descriptor BIO version of "Hello World":
  49. BIO *out;
  50. out = BIO_new_fd(fileno(stdout), BIO_NOCLOSE);
  51. BIO_printf(out, "Hello World\n");
  52. BIO_free(out);
  53. =head1 SEE ALSO
  54. L<BIO_seek(3)|BIO_seek(3)>, L<BIO_tell(3)|BIO_tell(3)>,
  55. L<BIO_reset(3)|BIO_reset(3)>, L<BIO_read(3)|BIO_read(3)>,
  56. L<BIO_write(3)|BIO_write(3)>, L<BIO_puts(3)|BIO_puts(3)>,
  57. L<BIO_gets(3)|BIO_gets(3)>, L<BIO_printf(3)|BIO_printf(3)>,
  58. L<BIO_set_close(3)|BIO_set_close(3)>, L<BIO_get_close(3)|BIO_get_close(3)>