1.\" $OpenBSD: BIO_ctrl.3,v 1.14 2018/03/27 17:35:50 schwarze Exp $ 2.\" OpenSSL b055fceb Thu Oct 20 09:56:18 2016 +0100 3.\" 4.\" This file was written by Dr. Stephen Henson <steve@openssl.org>. 5.\" Copyright (c) 2000, 2016 The OpenSSL Project. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in 16.\" the documentation and/or other materials provided with the 17.\" distribution. 18.\" 19.\" 3. All advertising materials mentioning features or use of this 20.\" software must display the following acknowledgment: 21.\" "This product includes software developed by the OpenSSL Project 22.\" for use in the OpenSSL Toolkit. (http://www.openssl.org/)" 23.\" 24.\" 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to 25.\" endorse or promote products derived from this software without 26.\" prior written permission. For written permission, please contact 27.\" openssl-core@openssl.org. 28.\" 29.\" 5. Products derived from this software may not be called "OpenSSL" 30.\" nor may "OpenSSL" appear in their names without prior written 31.\" permission of the OpenSSL Project. 32.\" 33.\" 6. Redistributions of any form whatsoever must retain the following 34.\" acknowledgment: 35.\" "This product includes software developed by the OpenSSL Project 36.\" for use in the OpenSSL Toolkit (http://www.openssl.org/)" 37.\" 38.\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY 39.\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 40.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 41.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR 42.\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 43.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 44.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 45.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 46.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, 47.\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 48.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED 49.\" OF THE POSSIBILITY OF SUCH DAMAGE. 50.\" 51.Dd $Mdocdate: March 27 2018 $ 52.Dt BIO_CTRL 3 53.Os 54.Sh NAME 55.Nm BIO_ctrl , 56.Nm BIO_callback_ctrl , 57.Nm BIO_ptr_ctrl , 58.Nm BIO_int_ctrl , 59.Nm BIO_reset , 60.Nm BIO_seek , 61.Nm BIO_tell , 62.Nm BIO_flush , 63.Nm BIO_eof , 64.Nm BIO_set_close , 65.Nm BIO_get_close , 66.Nm BIO_pending , 67.Nm BIO_wpending , 68.Nm BIO_ctrl_pending , 69.Nm BIO_ctrl_wpending , 70.Nm BIO_get_info_callback , 71.Nm BIO_set_info_callback , 72.Nm bio_info_cb 73.Nd BIO control operations 74.Sh SYNOPSIS 75.In openssl/bio.h 76.Ft long 77.Fo BIO_ctrl 78.Fa "BIO *bp" 79.Fa "int cmd" 80.Fa "long larg" 81.Fa "void *parg" 82.Fc 83.Ft long 84.Fo BIO_callback_ctrl 85.Fa "BIO *b" 86.Fa "int cmd" 87.Fa "bio_info_cb cb" 88.Fc 89.Ft char * 90.Fo BIO_ptr_ctrl 91.Fa "BIO *bp" 92.Fa "int cmd" 93.Fa "long larg" 94.Fc 95.Ft long 96.Fo BIO_int_ctrl 97.Fa "BIO *bp" 98.Fa "int cmd" 99.Fa "long larg" 100.Fa "int iarg" 101.Fc 102.Ft int 103.Fo BIO_reset 104.Fa "BIO *b" 105.Fc 106.Ft int 107.Fo BIO_seek 108.Fa "BIO *b" 109.Fa "int ofs" 110.Fc 111.Ft int 112.Fo BIO_tell 113.Fa "BIO *b" 114.Fc 115.Ft int 116.Fo BIO_flush 117.Fa "BIO *b" 118.Fc 119.Ft int 120.Fo BIO_eof 121.Fa "BIO *b" 122.Fc 123.Ft int 124.Fo BIO_set_close 125.Fa "BIO *b" 126.Fa "long flag" 127.Fc 128.Ft int 129.Fo BIO_get_close 130.Fa "BIO *b" 131.Fc 132.Ft int 133.Fo BIO_pending 134.Fa "BIO *b" 135.Fc 136.Ft int 137.Fo BIO_wpending 138.Fa "BIO *b" 139.Fc 140.Ft size_t 141.Fo BIO_ctrl_pending 142.Fa "BIO *b" 143.Fc 144.Ft size_t 145.Fo BIO_ctrl_wpending 146.Fa "BIO *b" 147.Fc 148.Ft int 149.Fo BIO_get_info_callback 150.Fa "BIO *b" 151.Fa "bio_info_cb **cbp" 152.Fc 153.Ft int 154.Fo BIO_set_info_callback 155.Fa "BIO *b" 156.Fa "bio_info_cb *cb" 157.Fc 158.Ft typedef void 159.Fo bio_info_cb 160.Fa "BIO *b" 161.Fa "int oper" 162.Fa "const char *ptr" 163.Fa "int arg1" 164.Fa "long arg2" 165.Fa "long arg3" 166.Fc 167.Sh DESCRIPTION 168.Fn BIO_ctrl , 169.Fn BIO_callback_ctrl , 170.Fn BIO_ptr_ctrl , 171and 172.Fn BIO_int_ctrl 173are BIO "control" operations taking arguments of various types. 174These functions are not normally called directly - 175various macros are used instead. 176The standard macros are described below. 177Macros specific to a particular type of BIO 178are described in the specific BIO's manual page 179as well as any special features of the standard calls. 180.Pp 181.Fn BIO_reset 182typically resets a BIO to some initial state. 183In the case of file related BIOs, for example, 184it rewinds the file pointer to the start of the file. 185.Pp 186.Fn BIO_seek 187resets a file related BIO's (that is file descriptor and 188FILE BIOs) file position pointer to 189.Fa ofs 190bytes from start of file. 191.Pp 192.Fn BIO_tell 193returns the current file position of a file related BIO. 194.Pp 195.Fn BIO_flush 196normally writes out any internally buffered data. 197In some cases it is used to signal EOF and that no more data will be written. 198.Pp 199.Fn BIO_eof 200returns 1 if the BIO has read EOF. 201The precise meaning of "EOF" varies according to the BIO type. 202.Pp 203.Fn BIO_set_close 204sets the BIO 205.Fa b 206close flag to 207.Fa flag . 208.Fa flag 209can take the value 210.Dv BIO_CLOSE 211or 212.Dv BIO_NOCLOSE . 213Typically 214.Dv BIO_CLOSE 215is used in a source/sink BIO to indicate that the underlying I/O stream 216should be closed when the BIO is freed. 217.Pp 218.Fn BIO_get_close 219returns the BIO's close flag. 220.Pp 221.Fn BIO_pending , 222.Fn BIO_ctrl_pending , 223.Fn BIO_wpending , 224and 225.Fn BIO_ctrl_wpending 226return the number of pending characters in the BIO's read and write buffers. 227Not all BIOs support these calls. 228.Fn BIO_ctrl_pending 229and 230.Fn BIO_ctrl_wpending 231return a 232.Vt size_t 233type and are functions. 234.Fn BIO_pending 235and 236.Fn BIO_wpending 237are macros which call 238.Fn BIO_ctrl . 239.Sh RETURN VALUES 240.Fn BIO_reset 241normally returns 1 for success and 0 or -1 for failure. 242File BIOs are an exception, returning 0 for success and -1 for failure. 243.Pp 244.Fn BIO_seek 245and 246.Fn BIO_tell 247both return the current file position on success 248and -1 for failure, except file BIOs which for 249.Fn BIO_seek 250always return 0 for success and -1 for failure. 251.Pp 252.Fn BIO_flush 253returns 1 for success and 0 or -1 for failure. 254.Pp 255.Fn BIO_eof 256returns 1 if EOF has been reached or 0 otherwise. 257.Pp 258.Fn BIO_set_close 259always returns 1. 260.Pp 261.Fn BIO_get_close 262returns the close flag value 263.Dv BIO_CLOSE 264or 265.Dv BIO_NOCLOSE . 266.Pp 267.Fn BIO_pending , 268.Fn BIO_ctrl_pending , 269.Fn BIO_wpending , 270and 271.Fn BIO_ctrl_wpending 272return the amount of pending data. 273.Sh NOTES 274Because it can write data, 275.Fn BIO_flush 276may return 0 or -1 indicating that the call should be retried later 277in a similar manner to 278.Xr BIO_write 3 . 279The 280.Xr BIO_should_retry 3 281call should be used and appropriate action taken if the call fails. 282.Pp 283The return values of 284.Fn BIO_pending 285and 286.Fn BIO_wpending 287may not reliably determine the amount of pending data in all cases. 288For example in the case of a file BIO some data may be available in the 289.Vt FILE 290structure's internal buffers but it is not possible 291to determine this in a portable way. 292For other types of BIO they may not be supported. 293.Pp 294If they do not internally handle a particular 295.Fn BIO_ctrl 296operation, filter BIOs usually pass the operation 297to the next BIO in the chain. 298This often means there is no need to locate the required BIO for 299a particular operation: it can be called on a chain and it will 300be automatically passed to the relevant BIO. 301However this can cause unexpected results. 302For example no current filter BIOs implement 303.Fn BIO_seek , 304but this may still succeed if the chain ends 305in a FILE or file descriptor BIO. 306.Pp 307Source/sink BIOs return an 0 if they do not recognize the 308.Fn BIO_ctrl 309operation. 310.Sh SEE ALSO 311.Xr BIO_meth_new 3 , 312.Xr BIO_new 3 313.Sh HISTORY 314.Fn BIO_ctrl , 315.Fn BIO_reset , 316.Fn BIO_flush , 317.Fn BIO_eof , 318.Fn BIO_set_close , 319.Fn BIO_get_close , 320and 321.Fn BIO_pending 322first appeared in SSLeay 0.6.0. 323.Fn BIO_wpending 324first appeared in SSLeay 0.8.1. 325.Fn BIO_ptr_ctrl , 326.Fn BIO_int_ctrl , 327.Fn BIO_get_info_callback 328and 329.Fn BIO_set_info_callback 330first appeared in SSLeay 0.9.0. 331All these functions have been available since 332.Ox 2.4 . 333.Pp 334.Fn BIO_seek 335and 336.Fn BIO_tell 337first appeared in SSLeay 0.9.1. 338.Fn BIO_ctrl_pending 339and 340.Fn BIO_ctrl_wpending 341first appeared in OpenSSL 0.9.4. 342These functions have been available since 343.Ox 2.6 . 344.Pp 345.Fn BIO_callback_ctrl 346first appeared in OpenSSL 0.9.5 and has been available since 347.Ox 2.7 . 348.Sh BUGS 349Some of the return values are ambiguous and care should be taken. 350In particular a return value of 0 can be returned if an operation 351is not supported, if an error occurred, if EOF has not been reached 352and in the case of 353.Fn BIO_seek 354on a file BIO for a successful operation. 355