BIO_f_buffer.pod 2.5 KB

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  1. =pod
  2. =head1 NAME
  3. BIO_f_buffer - buffering BIO
  4. =head1 SYNOPSIS
  5. #include <openssl/bio.h>
  6. BIO_METHOD * BIO_f_buffer(void);
  7. #define BIO_get_buffer_num_lines(b) BIO_ctrl(b,BIO_C_GET_BUFF_NUM_LINES,0,NULL)
  8. #define BIO_set_read_buffer_size(b,size) BIO_int_ctrl(b,BIO_C_SET_BUFF_SIZE,size,0)
  9. #define BIO_set_write_buffer_size(b,size) BIO_int_ctrl(b,BIO_C_SET_BUFF_SIZE,size,1)
  10. #define BIO_set_buffer_size(b,size) BIO_ctrl(b,BIO_C_SET_BUFF_SIZE,size,NULL)
  11. #define BIO_set_buffer_read_data(b,buf,num) BIO_ctrl(b,BIO_C_SET_BUFF_READ_DATA,num,buf)
  12. =head1 DESCRIPTION
  13. BIO_f_buffer() returns the buffering BIO method.
  14. Data written to a buffering BIO is buffered and periodically written
  15. to the next BIO in the chain. Data read from a buffering BIO comes from
  16. an internal buffer which is filled from the next BIO in the chain.
  17. Both BIO_gets() and BIO_puts() are supported.
  18. Calling BIO_reset() on a buffering BIO clears any buffered data.
  19. BIO_get_buffer_num_lines() returns the number of lines currently buffered.
  20. BIO_set_read_buffer_size(), BIO_set_write_buffer_size() and BIO_set_buffer_size()
  21. set the read, write or both read and write buffer sizes to B<size>. The initial
  22. buffer size is DEFAULT_BUFFER_SIZE, currently 1024. Any attempt to reduce the
  23. buffer size below DEFAULT_BUFFER_SIZE is ignored. Any buffered data is cleared
  24. when the buffer is resized.
  25. BIO_set_buffer_read_data() clears the read buffer and fills it with B<num>
  26. bytes of B<buf>. If B<num> is larger than the current buffer size the buffer
  27. is expanded.
  28. =head1 NOTES
  29. Buffering BIOs implement BIO_gets() by using BIO_read() operations on the
  30. next BIO in the chain. By prepending a buffering BIO to a chain it is therefore
  31. possible to provide BIO_gets() functionality if the following BIOs do not
  32. support it (for example SSL BIOs).
  33. Data is only written to the next BIO in the chain when the write buffer fills
  34. or when BIO_flush() is called. It is therefore important to call BIO_flush()
  35. whenever any pending data should be written such as when removing a buffering
  36. BIO using BIO_pop(). BIO_flush() may need to be retried if the ultimate
  37. source/sink BIO is non blocking.
  38. =head1 RETURN VALUES
  39. BIO_f_buffer() returns the buffering BIO method.
  40. BIO_get_buffer_num_lines() returns the number of lines buffered (may be 0).
  41. BIO_set_read_buffer_size(), BIO_set_write_buffer_size() and BIO_set_buffer_size()
  42. return 1 if the buffer was successfully resized or 0 for failure.
  43. BIO_set_buffer_read_data() returns 1 if the data was set correctly or 0 if
  44. there was an error.
  45. =head1 SEE ALSO
  46. TBA