BIO_f_buffer (3)

Leading comments

Automatically generated by Pod::Man 4.07 (Pod::Simple 3.32)

Standard preamble:
========================================================================

(The comments found at the beginning of the groff file "man3/BIO_f_buffer.3ssl".)

NAME

BIO_f_buffer - buffering BIO

SYNOPSIS

 #include <openssl/bio.h>

 BIO_METHOD * BIO_f_buffer(void);

 #define BIO_get_buffer_num_lines(b)    BIO_ctrl(b,BIO_C_GET_BUFF_NUM_LINES,0,NULL)
 #define BIO_set_read_buffer_size(b,size) BIO_int_ctrl(b,BIO_C_SET_BUFF_SIZE,size,0)
 #define BIO_set_write_buffer_size(b,size) BIO_int_ctrl(b,BIO_C_SET_BUFF_SIZE,size,1)
 #define BIO_set_buffer_size(b,size)    BIO_ctrl(b,BIO_C_SET_BUFF_SIZE,size,NULL)
 #define BIO_set_buffer_read_data(b,buf,num) BIO_ctrl(b,BIO_C_SET_BUFF_READ_DATA,num,buf)

DESCRIPTION

BIO_f_buffer() returns the buffering method.

Data written to a buffering

is buffered and periodically written to the next in the chain. Data read from a buffering comes from an internal buffer which is filled from the next in the chain. Both BIO_gets() and BIO_puts() are supported.

Calling BIO_reset() on a buffering

clears any buffered data.

BIO_get_buffer_num_lines() returns the number of lines currently buffered.

BIO_set_read_buffer_size(), BIO_set_write_buffer_size() and BIO_set_buffer_size() set the read, write or both read and write buffer sizes to size. The initial buffer size is

currently 4096. Any attempt to reduce the buffer size below is ignored. Any buffered data is cleared when the buffer is resized.

BIO_set_buffer_read_data() clears the read buffer and fills it with num bytes of buf. If num is larger than the current buffer size the buffer is expanded.

NOTES

Buffering BIOs implement BIO_gets() by using BIO_read() operations on the next in the chain. By prepending a buffering to a chain it is therefore possible to provide BIO_gets() functionality if the following BIOs do not support it (for example BIOs).

Data is only written to the next

in the chain when the write buffer fills or when BIO_flush() is called. It is therefore important to call BIO_flush() whenever any pending data should be written such as when removing a buffering using BIO_pop(). BIO_flush() may need to be retried if the ultimate source/sink is non blocking.

RETURN VALUES

BIO_f_buffer() returns the buffering method.

BIO_get_buffer_num_lines() returns the number of lines buffered (may be 0).

BIO_set_read_buffer_size(), BIO_set_write_buffer_size() and BIO_set_buffer_size() return 1 if the buffer was successfully resized or 0 for failure.

BIO_set_buffer_read_data() returns 1 if the data was set correctly or 0 if there was an error.

SEE ALSO

(3), BIO_reset(3), BIO_flush(3), BIO_pop(3), BIO_ctrl(3), BIO_int_ctrl(3)