$NetBSD: BIO_f_buffer.3,v 1.14 2015/06/12 17:01:13 christos Exp $

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Title "BIO_f_buffer 3" For nroff, turn off justification. Always turn off hyphenation; it makes
way too many mistakes in technical documents.
BIO_f_buffer - buffering BIO libcrypto, -lcrypto Header "SYNOPSIS" .Vb 1 #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) .Ve Header "DESCRIPTION" \fIBIO_f_buffer() returns the buffering \s-1BIO\s0 method.

Data written to a buffering \s-1BIO\s0 is buffered and periodically written to the next \s-1BIO\s0 in the chain. Data read from a buffering \s-1BIO\s0 comes from an internal buffer which is filled from the next \s-1BIO\s0 in the chain. Both BIO_gets() and BIO_puts() are supported.

Calling BIO_reset() on a buffering \s-1BIO\s0 clears any buffered data.

\fIBIO_get_buffer_num_lines() returns the number of lines currently buffered.

\fIBIO_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 \s-1DEFAULT_BUFFER_SIZE,\s0 currently 4096. Any attempt to reduce the buffer size below \s-1DEFAULT_BUFFER_SIZE\s0 is ignored. Any buffered data is cleared when the buffer is resized.

\fIBIO_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.

Header "NOTES" Buffering BIOs implement BIO_gets() by using BIO_read() operations on the next \s-1BIO\s0 in the chain. By prepending a buffering \s-1BIO\s0 to a chain it is therefore possible to provide BIO_gets() functionality if the following BIOs do not support it (for example \s-1SSL\s0 BIOs).

Data is only written to the next \s-1BIO\s0 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 \s-1BIO\s0 using BIO_pop(). BIO_flush() may need to be retried if the ultimate source/sink \s-1BIO\s0 is non blocking.

Header "RETURN VALUES" \fIBIO_f_buffer() returns the buffering \s-1BIO\s0 method.

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

\fIBIO_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.

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

Header "SEE ALSO" \s-1BIO\s0\|(3), \fIBIO_reset\|(3), \fIBIO_flush\|(3), \fIBIO_pop\|(3), \fIBIO_ctrl\|(3), \fIBIO_int_ctrl\|(3)