BIO_F_BUFFER(3) BSD Library Functions Manual BIO_F_BUFFER(3)NAMEBIO_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)
DESCRIPTIONBIO_f_buffer() returns the buffering BIO method.
Data written to a buffering BIO is buffered and periodically written to
the next BIO in the chain. Data read from a buffering BIO comes from an
internal buffer which is filled from the next BIO in the chain. Both
BIO_gets(3) and BIO_puts(3) are supported.
Calling BIO_reset(3) on a buffering BIO 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 DEFAULT_BUFFER_SIZE, currently
4096. Any attempt to reduce the buffer size below DEFAULT_BUFFER_SIZE 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(3) by using BIO_read(3) operations on
the next BIO in the chain. By prepending a buffering BIO to a chain it
is therefore possible to provide BIO_gets(3) functionality if the follow‐
ing BIOs do not support it (for example SSL BIOs).
Data is only written to the next BIO in the chain when the write buffer
fills or when BIO_flush(3) is called. It is therefore important to call
BIO_flush(3) whenever any pending data should be written such as when
removing a buffering BIO using BIO_pop(3). BIO_flush(3) may need to be
retried if the ultimate source/sink BIO is non blocking.
RETURN VALUESBIO_f_buffer() returns the buffering BIO 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 ALSOBIO(3), BIO_ctrl(3), BIO_flush(3), BIO_pop(3), BIO_reset(3)BSD July 17, 2014 BSD
