Edit File: BIO_callback_ctrl.3
.\" Automatically generated by Pod::Man 4.11 (Pod::Simple 3.35) .\" .\" Standard preamble: .\" ======================================================================== .de Sp \" Vertical space (when we can't use .PP) .if t .sp .5v .if n .sp .. .de Vb \" Begin verbatim text .ft CW .nf .ne \\$1 .. .de Ve \" End verbatim text .ft R .fi .. .\" Set up some character translations and predefined strings. \*(-- will .\" give an unbreakable dash, \*(PI will give pi, \*(L" will give a left .\" double quote, and \*(R" will give a right double quote. \*(C+ will .\" give a nicer C++. Capital omega is used to do unbreakable dashes and .\" therefore won't be available. \*(C` and \*(C' expand to `' in nroff, .\" nothing in troff, for use with C<>. .tr \(*W- .ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p' .ie n \{\ . ds -- \(*W- . ds PI pi . if (\n(.H=4u)&(1m=24u) .ds -- \(*W\h'-12u'\(*W\h'-12u'-\" diablo 10 pitch . if (\n(.H=4u)&(1m=20u) .ds -- \(*W\h'-12u'\(*W\h'-8u'-\" diablo 12 pitch . ds L" "" . ds R" "" . ds C` "" . ds C' "" 'br\} .el\{\ . ds -- \|\(em\| . ds PI \(*p . ds L" `` . ds R" '' . ds C` . ds C' 'br\} .\" .\" Escape single quotes in literal strings from groff's Unicode transform. .ie \n(.g .ds Aq \(aq .el .ds Aq ' .\" .\" If the F register is >0, we'll generate index entries on stderr for .\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index .\" entries marked with X<> in POD. Of course, you'll have to process the .\" output yourself in some meaningful fashion. .\" .\" Avoid warning from groff about undefined register 'F'. .de IX .. .nr rF 0 .if \n(.g .if rF .nr rF 1 .if (\n(rF:(\n(.g==0)) \{\ . if \nF \{\ . de IX . tm Index:\\$1\t\\n%\t"\\$2" .. . if !\nF==2 \{\ . nr % 0 . nr F 2 . \} . \} .\} .rr rF .\" .\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2). .\" Fear. Run. Save yourself. No user-serviceable parts. . \" fudge factors for nroff and troff .if n \{\ . ds #H 0 . ds #V .8m . ds #F .3m . ds #[ \f1 . ds #] \fP .\} .if t \{\ . ds #H ((1u-(\\\\n(.fu%2u))*.13m) . ds #V .6m . ds #F 0 . ds #[ \& . ds #] \& .\} . \" simple accents for nroff and troff .if n \{\ . ds ' \& . ds ` \& . ds ^ \& . ds , \& . ds ~ ~ . ds / .\} .if t \{\ . ds ' \\k:\h'-(\\n(.wu*8/10-\*(#H)'\'\h"|\\n:u" . ds ` \\k:\h'-(\\n(.wu*8/10-\*(#H)'\`\h'|\\n:u' . ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'^\h'|\\n:u' . ds , \\k:\h'-(\\n(.wu*8/10)',\h'|\\n:u' . ds ~ \\k:\h'-(\\n(.wu-\*(#H-.1m)'~\h'|\\n:u' . ds / \\k:\h'-(\\n(.wu*8/10-\*(#H)'\z\(sl\h'|\\n:u' .\} . \" troff and (daisy-wheel) nroff accents .ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V' .ds 8 \h'\*(#H'\(*b\h'-\*(#H' .ds o \\k:\h'-(\\n(.wu+\w'\(de'u-\*(#H)/2u'\v'-.3n'\*(#[\z\(de\v'.3n'\h'|\\n:u'\*(#] .ds d- \h'\*(#H'\(pd\h'-\w'~'u'\v'-.25m'\f2\(hy\fP\v'.25m'\h'-\*(#H' .ds D- D\\k:\h'-\w'D'u'\v'-.11m'\z\(hy\v'.11m'\h'|\\n:u' .ds th \*(#[\v'.3m'\s+1I\s-1\v'-.3m'\h'-(\w'I'u*2/3)'\s-1o\s+1\*(#] .ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#] .ds ae a\h'-(\w'a'u*4/10)'e .ds Ae A\h'-(\w'A'u*4/10)'E . \" corrections for vroff .if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u' .if v .ds ^ \\k:\h'-(\\n(.wu*10/11-\*(#H)'\v'-.4m'^\v'.4m'\h'|\\n:u' . \" for low resolution devices (crt and lpr) .if \n(.H>23 .if \n(.V>19 \ \{\ . ds : e . ds 8 ss . ds o a . ds d- d\h'-1'\(ga . ds D- D\h'-1'\(hy . ds th \o'bp' . ds Th \o'LP' . ds ae ae . ds Ae AE .\} .rm #[ #] #H #V #F C .\" ======================================================================== .\" .IX Title "BIO_ctrl 3" .TH BIO_ctrl 3 "2019-12-20" "1.0.2u" "OpenSSL" .\" For nroff, turn off justification. Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH "NAME" BIO_ctrl, BIO_callback_ctrl, BIO_ptr_ctrl, BIO_int_ctrl, BIO_reset, BIO_seek, BIO_tell, BIO_flush, BIO_eof, BIO_set_close, BIO_get_close, BIO_pending, BIO_wpending, BIO_ctrl_pending, BIO_ctrl_wpending, BIO_get_info_callback, BIO_set_info_callback \- BIO control operations .SH "SYNOPSIS" .IX Header "SYNOPSIS" .Vb 1 \& #include <openssl/bio.h> \& \& long BIO_ctrl(BIO *bp,int cmd,long larg,void *parg); \& long BIO_callback_ctrl(BIO *b, int cmd, void (*fp)(struct bio_st *, int, const char *, int, long, long)); \& char * BIO_ptr_ctrl(BIO *bp,int cmd,long larg); \& long BIO_int_ctrl(BIO *bp,int cmd,long larg,int iarg); \& \& int BIO_reset(BIO *b); \& int BIO_seek(BIO *b, int ofs); \& int BIO_tell(BIO *b); \& int BIO_flush(BIO *b); \& int BIO_eof(BIO *b); \& int BIO_set_close(BIO *b,long flag); \& int BIO_get_close(BIO *b); \& int BIO_pending(BIO *b); \& int BIO_wpending(BIO *b); \& size_t BIO_ctrl_pending(BIO *b); \& size_t BIO_ctrl_wpending(BIO *b); \& \& int BIO_get_info_callback(BIO *b,bio_info_cb **cbp); \& int BIO_set_info_callback(BIO *b,bio_info_cb *cb); \& \& typedef void bio_info_cb(BIO *b, int oper, const char *ptr, int arg1, long arg2, long arg3); .Ve .SH "DESCRIPTION" .IX Header "DESCRIPTION" \&\fBBIO_ctrl()\fR, \fBBIO_callback_ctrl()\fR, \fBBIO_ptr_ctrl()\fR and \fBBIO_int_ctrl()\fR are \s-1BIO\s0 \*(L"control\*(R" operations taking arguments of various types. These functions are not normally called directly, various macros are used instead. The standard macros are described below, macros specific to a particular type of \s-1BIO\s0 are described in the specific BIOs manual page as well as any special features of the standard calls. .PP \&\fBBIO_reset()\fR typically resets a \s-1BIO\s0 to some initial state, in the case of file related BIOs for example it rewinds the file pointer to the start of the file. .PP \&\fBBIO_seek()\fR resets a file related \s-1BIO\s0's (that is file descriptor and \&\s-1FILE\s0 BIOs) file position pointer to \fBofs\fR bytes from start of file. .PP \&\fBBIO_tell()\fR returns the current file position of a file related \s-1BIO.\s0 .PP \&\fBBIO_flush()\fR normally writes out any internally buffered data, in some cases it is used to signal \s-1EOF\s0 and that no more data will be written. .PP \&\fBBIO_eof()\fR returns 1 if the \s-1BIO\s0 has read \s-1EOF,\s0 the precise meaning of \&\*(L"\s-1EOF\*(R"\s0 varies according to the \s-1BIO\s0 type. .PP \&\fBBIO_set_close()\fR sets the \s-1BIO\s0 \fBb\fR close flag to \fBflag\fR. \fBflag\fR can take the value \s-1BIO_CLOSE\s0 or \s-1BIO_NOCLOSE.\s0 Typically \s-1BIO_CLOSE\s0 is used in a source/sink \s-1BIO\s0 to indicate that the underlying I/O stream should be closed when the \s-1BIO\s0 is freed. .PP \&\fBBIO_get_close()\fR returns the BIOs close flag. .PP \&\fBBIO_pending()\fR, \fBBIO_ctrl_pending()\fR, \fBBIO_wpending()\fR and \fBBIO_ctrl_wpending()\fR return the number of pending characters in the BIOs read and write buffers. Not all BIOs support these calls. \fBBIO_ctrl_pending()\fR and \fBBIO_ctrl_wpending()\fR return a size_t type and are functions, \fBBIO_pending()\fR and \fBBIO_wpending()\fR are macros which call \fBBIO_ctrl()\fR. .SH "RETURN VALUES" .IX Header "RETURN VALUES" \&\fBBIO_reset()\fR normally returns 1 for success and 0 or \-1 for failure. File BIOs are an exception, they return 0 for success and \-1 for failure. .PP \&\fBBIO_seek()\fR and \fBBIO_tell()\fR both return the current file position on success and \-1 for failure, except file BIOs which for \fBBIO_seek()\fR always return 0 for success and \-1 for failure. .PP \&\fBBIO_flush()\fR returns 1 for success and 0 or \-1 for failure. .PP \&\fBBIO_eof()\fR returns 1 if \s-1EOF\s0 has been reached 0 otherwise. .PP \&\fBBIO_set_close()\fR always returns 1. .PP \&\fBBIO_get_close()\fR returns the close flag value: \s-1BIO_CLOSE\s0 or \s-1BIO_NOCLOSE.\s0 .PP \&\fBBIO_pending()\fR, \fBBIO_ctrl_pending()\fR, \fBBIO_wpending()\fR and \fBBIO_ctrl_wpending()\fR return the amount of pending data. .SH "NOTES" .IX Header "NOTES" \&\fBBIO_flush()\fR, because it can write data may return 0 or \-1 indicating that the call should be retried later in a similar manner to \fBBIO_write()\fR. The \fBBIO_should_retry()\fR call should be used and appropriate action taken is the call fails. .PP The return values of \fBBIO_pending()\fR and \fBBIO_wpending()\fR may not reliably determine the amount of pending data in all cases. For example in the case of a file \s-1BIO\s0 some data may be available in the \s-1FILE\s0 structures internal buffers but it is not possible to determine this in a portably way. For other types of \s-1BIO\s0 they may not be supported. .PP Filter BIOs if they do not internally handle a particular \fBBIO_ctrl()\fR operation usually pass the operation to the next \s-1BIO\s0 in the chain. This often means there is no need to locate the required \s-1BIO\s0 for a particular operation, it can be called on a chain and it will be automatically passed to the relevant \s-1BIO.\s0 However this can cause unexpected results: for example no current filter BIOs implement \&\fBBIO_seek()\fR, but this may still succeed if the chain ends in a \s-1FILE\s0 or file descriptor \s-1BIO.\s0 .PP Source/sink BIOs return an 0 if they do not recognize the \fBBIO_ctrl()\fR operation. .SH "BUGS" .IX Header "BUGS" Some of the return values are ambiguous and care should be taken. In particular a return value of 0 can be returned if an operation is not supported, if an error occurred, if \s-1EOF\s0 has not been reached and in the case of \fBBIO_seek()\fR on a file \s-1BIO\s0 for a successful operation. .SH "SEE ALSO" .IX Header "SEE ALSO" \&\s-1TBA\s0