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137 .IX Title "BIO_f_buffer 3"
138 .TH BIO_f_buffer 3 "2011-06-05" "1.0.1n" "OpenSSL"
139 .\" For nroff, turn off justification. Always turn off hyphenation; it makes
140 .\" way too many mistakes in technical documents.
141 .if n .ad l
142 .nh
143 .SH "NAME"
144 BIO_f_buffer \- buffering BIO
145 .SH "LIBRARY"
146 libcrypto, -lcrypto
147 .SH "SYNOPSIS"
148 .IX Header "SYNOPSIS"
149 .Vb 1
150 \& #include <openssl/bio.h>
151 \&
152 \& BIO_METHOD * BIO_f_buffer(void);
153 \&
154 \& #define BIO_get_buffer_num_lines(b) BIO_ctrl(b,BIO_C_GET_BUFF_NUM_LINES,0,NULL)
155 \& #define BIO_set_read_buffer_size(b,size) BIO_int_ctrl(b,BIO_C_SET_BUFF_SIZE,size,0)
156 \& #define BIO_set_write_buffer_size(b,size) BIO_int_ctrl(b,BIO_C_SET_BUFF_SIZE,size,1)
157 \& #define BIO_set_buffer_size(b,size) BIO_ctrl(b,BIO_C_SET_BUFF_SIZE,size,NULL)
158 \& #define BIO_set_buffer_read_data(b,buf,num) BIO_ctrl(b,BIO_C_SET_BUFF_READ_DATA,num,buf)
159 .Ve
160 .SH "DESCRIPTION"
161 .IX Header "DESCRIPTION"
162 \&\fIBIO_f_buffer()\fR returns the buffering \s-1BIO\s0 method.
163 .PP
164 Data written to a buffering \s-1BIO\s0 is buffered and periodically written
165 to the next \s-1BIO\s0 in the chain. Data read from a buffering \s-1BIO\s0 comes from
166 an internal buffer which is filled from the next \s-1BIO\s0 in the chain.
167 Both \fIBIO_gets()\fR and \fIBIO_puts()\fR are supported.
168 .PP
169 Calling \fIBIO_reset()\fR on a buffering \s-1BIO\s0 clears any buffered data.
170 .PP
171 \&\fIBIO_get_buffer_num_lines()\fR returns the number of lines currently buffered.
172 .PP
173 \&\fIBIO_set_read_buffer_size()\fR, \fIBIO_set_write_buffer_size()\fR and \fIBIO_set_buffer_size()\fR
174 set the read, write or both read and write buffer sizes to \fBsize\fR. The initial
175 buffer size is \s-1DEFAULT_BUFFER_SIZE,\s0 currently 4096. Any attempt to reduce the
176 buffer size below \s-1DEFAULT_BUFFER_SIZE\s0 is ignored. Any buffered data is cleared
177 when the buffer is resized.
178 .PP
179 \&\fIBIO_set_buffer_read_data()\fR clears the read buffer and fills it with \fBnum\fR
180 bytes of \fBbuf\fR. If \fBnum\fR is larger than the current buffer size the buffer
181 is expanded.
182 .SH "NOTES"
183 .IX Header "NOTES"
184 Buffering BIOs implement \fIBIO_gets()\fR by using \fIBIO_read()\fR operations on the
185 next \s-1BIO\s0 in the chain. By prepending a buffering \s-1BIO\s0 to a chain it is therefore
186 possible to provide \fIBIO_gets()\fR functionality if the following BIOs do not
187 support it (for example \s-1SSL\s0 BIOs).
188 .PP
189 Data is only written to the next \s-1BIO\s0 in the chain when the write buffer fills
190 or when \fIBIO_flush()\fR is called. It is therefore important to call \fIBIO_flush()\fR
191 whenever any pending data should be written such as when removing a buffering
192 \&\s-1BIO\s0 using \fIBIO_pop()\fR. \fIBIO_flush()\fR may need to be retried if the ultimate
193 source/sink \s-1BIO\s0 is non blocking.
194 .SH "RETURN VALUES"
195 .IX Header "RETURN VALUES"
196 \&\fIBIO_f_buffer()\fR returns the buffering \s-1BIO\s0 method.
197 .PP
198 \&\fIBIO_get_buffer_num_lines()\fR returns the number of lines buffered (may be 0).
199 .PP
200 \&\fIBIO_set_read_buffer_size()\fR, \fIBIO_set_write_buffer_size()\fR and \fIBIO_set_buffer_size()\fR
201 return 1 if the buffer was successfully resized or 0 for failure.
202 .PP
203 \&\fIBIO_set_buffer_read_data()\fR returns 1 if the data was set correctly or 0 if
204 there was an error.
205 .SH "SEE ALSO"
206 .IX Header "SEE ALSO"
207 \&\s-1\fIBIO\s0\fR\|(3),
208 \&\fIBIO_reset\fR\|(3),
209 \&\fIBIO_flush\fR\|(3),
210 \&\fIBIO_pop\fR\|(3),
211 \&\fIBIO_ctrl\fR\|(3),
212 \&\fIBIO_int_ctrl\fR\|(3)