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. const BIO_METHOD *BIO_s_fd(void);
  7. int BIO_set_fd(BIO *b, int fd, int c);
  8. int BIO_get_fd(BIO *b, int *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_ex() and BIO_write_ex() read or write the underlying descriptor.
  14. BIO_puts() is supported but BIO_gets() is not.
  15. If the close flag is set 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. such as by using B<lseek(fd, 0, 0)>.
  19. BIO_seek() sets the file pointer to position B<ofs> from start of file
  20. such as by using B<lseek(fd, ofs, 0)>.
  21. BIO_tell() returns the current file position such as by calling
  22. B<lseek(fd, 0, 1)>.
  23. BIO_set_fd() sets the file descriptor of BIO B<b> to B<fd> and the close
  24. flag to B<c>.
  25. BIO_get_fd() places the file descriptor of BIO B<b> in B<c> if it is not NULL.
  26. It also returns the file descriptor.
  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_ex() and BIO_write_ex() 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_ex(3)> and L<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. BIO_set_fd() and BIO_get_fd() are implemented as macros.
  37. =head1 RETURN VALUES
  38. BIO_s_fd() returns the file descriptor BIO method.
  39. BIO_set_fd() returns 1 on success or <=0 for failure.
  40. BIO_get_fd() returns the file descriptor or -1 if the BIO has not
  41. been initialized. It also returns zero and negative values if other error occurs.
  42. BIO_new_fd() returns the newly allocated BIO or NULL is an error
  43. occurred.
  44. =head1 EXAMPLES
  45. This is a file descriptor BIO version of "Hello World":
  46. BIO *out;
  47. out = BIO_new_fd(fileno(stdout), BIO_NOCLOSE);
  48. BIO_printf(out, "Hello World\n");
  49. BIO_free(out);
  50. =head1 SEE ALSO
  51. L<BIO_seek(3)>, L<BIO_tell(3)>,
  52. L<BIO_reset(3)>, L<BIO_read_ex(3)>,
  53. L<BIO_write_ex(3)>, L<BIO_puts(3)>,
  54. L<BIO_gets(3)>, L<BIO_printf(3)>,
  55. L<BIO_set_close(3)>, L<BIO_get_close(3)>
  56. =head1 COPYRIGHT
  57. Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.
  58. Licensed under the Apache License 2.0 (the "License"). You may not use
  59. this file except in compliance with the License. You can obtain a copy
  60. in the file LICENSE in the source distribution or at
  61. L<https://www.openssl.org/source/license.html>.
  62. =cut