bio_f_buffer(3ssl) [linux man page]

BIO_f_buffer(3SSL)						      OpenSSL							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 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() and BIO_puts() are supported.

       Calling BIO_reset() 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() by using BIO_read() operations on the next BIO in the chain. By prepending a buffering BIO to a chain
       it is therefore possible to provide BIO_gets() functionality if the following 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() is called. It is therefore important to
       call BIO_flush() whenever any pending data should be written such as when removing a buffering BIO using BIO_pop(). BIO_flush() may need to
       be retried if the ultimate source/sink BIO is non blocking.

RETURN VALUES

       BIO_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 ALSO

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

1.0.0e								    2010-05-03							BIO_f_buffer(3SSL)

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BIO_read(3SSL)							      OpenSSL							    BIO_read(3SSL)

NAME

       BIO_read, BIO_write, BIO_gets, BIO_puts - BIO I/O functions

SYNOPSIS

	#include <openssl/bio.h>

	int    BIO_read(BIO *b, void *buf, int len);
	int    BIO_gets(BIO *b,char *buf, int size);
	int    BIO_write(BIO *b, const void *buf, int len);
	int    BIO_puts(BIO *b,const char *buf);

DESCRIPTION

       BIO_read() attempts to read len bytes from BIO b and places the data in buf.

       BIO_gets() performs the BIOs "gets" operation and places the data in buf. Usually this operation will attempt to read a line of data from
       the BIO of maximum length len. There are exceptions to this however, for example BIO_gets() on a digest BIO will calculate and return the
       digest and other BIOs may not support BIO_gets() at all.

       BIO_write() attempts to write len bytes from buf to BIO b.

       BIO_puts() attempts to write a null terminated string buf to BIO b

RETURN VALUES

       All these functions return either the amount of data successfully read or written (if the return value is positive) or that no data was
       successfully read or written if the result is 0 or -1. If the return value is -2 then the operation is not implemented in the specific BIO
       type.

NOTES

       A 0 or -1 return is not necessarily an indication of an error. In particular when the source/sink is non-blocking or of a certain type it
       may merely be an indication that no data is currently available and that the application should retry the operation later.

       One technique sometimes used with blocking sockets is to use a system call (such as select(), poll() or equivalent) to determine when data
       is available and then call read() to read the data. The equivalent with BIOs (that is call select() on the underlying I/O structure and
       then call BIO_read() to read the data) should not be used because a single call to BIO_read() can cause several reads (and writes in the
       case of SSL BIOs) on the underlying I/O structure and may block as a result. Instead select() (or equivalent) should be combined with non
       blocking I/O so successive reads will request a retry instead of blocking.

       See BIO_should_retry(3) for details of how to determine the cause of a retry and other I/O issues.

       If the BIO_gets() function is not supported by a BIO then it possible to work around this by adding a buffering BIO BIO_f_buffer(3) to the
       chain.

SEE ALSO

       BIO_should_retry(3)

       TBA

1.0.0e								    2000-09-16							    BIO_read(3SSL)

Linux and UNIX Man Pages

bio_f_buffer(3ssl) [linux man page]

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