74 lines
2.7 KiB
Text
74 lines
2.7 KiB
Text
=pod
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=head1 NAME
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BIO_f_buffer - buffering BIO
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=head1 SYNOPSIS
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#include <openssl/bio.h>
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BIO_METHOD * BIO_f_buffer(void);
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#define BIO_get_buffer_num_lines(b) BIO_ctrl(b,BIO_C_GET_BUFF_NUM_LINES,0,NULL)
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#define BIO_set_read_buffer_size(b,size) BIO_int_ctrl(b,BIO_C_SET_BUFF_SIZE,size,0)
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#define BIO_set_write_buffer_size(b,size) BIO_int_ctrl(b,BIO_C_SET_BUFF_SIZE,size,1)
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#define BIO_set_buffer_size(b,size) BIO_ctrl(b,BIO_C_SET_BUFF_SIZE,size,NULL)
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#define BIO_set_buffer_read_data(b,buf,num) BIO_ctrl(b,BIO_C_SET_BUFF_READ_DATA,num,buf)
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=head1 DESCRIPTION
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BIO_f_buffer() returns the buffering BIO method.
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Data written to a buffering BIO is buffered and periodically written
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to the next BIO in the chain. Data read from a buffering BIO comes from
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an internal buffer which is filled from the next BIO in the chain.
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Both BIO_gets() and BIO_puts() are supported.
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Calling BIO_reset() on a buffering BIO clears any buffered data.
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BIO_get_buffer_num_lines() returns the number of lines currently buffered.
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BIO_set_read_buffer_size(), BIO_set_write_buffer_size() and BIO_set_buffer_size()
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set the read, write or both read and write buffer sizes to B<size>. The initial
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buffer size is DEFAULT_BUFFER_SIZE, currently 4096. Any attempt to reduce the
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buffer size below DEFAULT_BUFFER_SIZE is ignored. Any buffered data is cleared
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when the buffer is resized.
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BIO_set_buffer_read_data() clears the read buffer and fills it with B<num>
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bytes of B<buf>. If B<num> is larger than the current buffer size the buffer
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is expanded.
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=head1 NOTES
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Buffering BIOs implement BIO_gets() by using BIO_read() operations on the
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next BIO in the chain. By prepending a buffering BIO to a chain it is therefore
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possible to provide BIO_gets() functionality if the following BIOs do not
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support it (for example SSL BIOs).
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Data is only written to the next BIO in the chain when the write buffer fills
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or when BIO_flush() is called. It is therefore important to call BIO_flush()
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whenever any pending data should be written such as when removing a buffering
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BIO using BIO_pop(). BIO_flush() may need to be retried if the ultimate
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source/sink BIO is non blocking.
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=head1 RETURN VALUES
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BIO_f_buffer() returns the buffering BIO method.
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BIO_get_buffer_num_lines() returns the number of lines buffered (may be 0).
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BIO_set_read_buffer_size(), BIO_set_write_buffer_size() and BIO_set_buffer_size()
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return 1 if the buffer was successfully resized or 0 for failure.
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BIO_set_buffer_read_data() returns 1 if the data was set correctly or 0 if
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there was an error.
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=head1 SEE ALSO
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L<BIO(3)|BIO(3)>,
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L<BIO_reset(3)|BIO_reset(3)>,
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L<BIO_flush(3)|BIO_flush(3)>,
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L<BIO_pop(3)|BIO_pop(3)>,
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L<BIO_ctrl(3)|BIO_ctrl(3)>,
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L<BIO_int_ctrl(3)|BIO_ctrl(3)>
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