208 lines
6.5 KiB
Groff
208 lines
6.5 KiB
Groff
.\" $NetBSD: BIO_read.3,v 1.8 2003/07/24 14:16:36 itojun Exp $
|
|
.\"
|
|
.\" Automatically generated by Pod::Man version 1.02
|
|
.\" Thu Jul 24 13:07:49 2003
|
|
.\"
|
|
.\" Standard preamble:
|
|
.\" ======================================================================
|
|
.de Sh \" Subsection heading
|
|
.br
|
|
.if t .Sp
|
|
.ne 5
|
|
.PP
|
|
\fB\\$1\fR
|
|
.PP
|
|
..
|
|
.de Sp \" Vertical space (when we can't use .PP)
|
|
.if t .sp .5v
|
|
.if n .sp
|
|
..
|
|
.de Ip \" List item
|
|
.br
|
|
.ie \\n(.$>=3 .ne \\$3
|
|
.el .ne 3
|
|
.IP "\\$1" \\$2
|
|
..
|
|
.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. | will give a
|
|
.\" real vertical bar. \*(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-|\(bv\*(Tr
|
|
.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" ''
|
|
'br\}
|
|
.\"
|
|
.\" If the F register is turned on, we'll generate index entries on stderr
|
|
.\" for titles (.TH), headers (.SH), subsections (.Sh), items (.Ip), and
|
|
.\" index entries marked with X<> in POD. Of course, you'll have to process
|
|
.\" the output yourself in some meaningful fashion.
|
|
.if \nF \{\
|
|
. de IX
|
|
. tm Index:\\$1\t\\n%\t"\\$2"
|
|
. .
|
|
. nr % 0
|
|
. rr F
|
|
.\}
|
|
.\"
|
|
.\" For nroff, turn off justification. Always turn off hyphenation; it
|
|
.\" makes way too many mistakes in technical documents.
|
|
.hy 0
|
|
.if n .na
|
|
.\"
|
|
.\" Accent mark definitions (@(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2).
|
|
.\" Fear. Run. Save yourself. No user-serviceable parts.
|
|
.bd B 3
|
|
. \" 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_read 3"
|
|
.TH BIO_read 3 "0.9.7b" "2000-09-17" "OpenSSL"
|
|
.UC
|
|
.SH "NAME"
|
|
BIO_read, BIO_write, BIO_gets, BIO_puts \- \s-1BIO\s0 I/O functions
|
|
.SH "LIBRARY"
|
|
libcrypto, -lcrypto
|
|
.SH "SYNOPSIS"
|
|
.IX Header "SYNOPSIS"
|
|
.Vb 1
|
|
\& #include <openssl/bio.h>
|
|
.Ve
|
|
.Vb 4
|
|
\& 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);
|
|
.Ve
|
|
.SH "DESCRIPTION"
|
|
.IX Header "DESCRIPTION"
|
|
\&\fIBIO_read()\fR attempts to read \fBlen\fR bytes from \s-1BIO\s0 \fBb\fR and places
|
|
the data in \fBbuf\fR.
|
|
.PP
|
|
\&\fIBIO_gets()\fR performs the BIOs \*(L"gets\*(R" operation and places the data
|
|
in \fBbuf\fR. Usually this operation will attempt to read a line of data
|
|
from the \s-1BIO\s0 of maximum length \fBlen\fR. There are exceptions to this
|
|
however, for example \fIBIO_gets()\fR on a digest \s-1BIO\s0 will calculate and
|
|
return the digest and other BIOs may not support \fIBIO_gets()\fR at all.
|
|
.PP
|
|
\&\fIBIO_write()\fR attempts to write \fBlen\fR bytes from \fBbuf\fR to \s-1BIO\s0 \fBb\fR.
|
|
.PP
|
|
\&\fIBIO_puts()\fR attempts to write a null terminated string \fBbuf\fR to \s-1BIO\s0 \fBb\fR
|
|
.SH "RETURN VALUES"
|
|
.IX Header "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 \s-1BIO\s0 type.
|
|
.SH "NOTES"
|
|
.IX Header "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.
|
|
.PP
|
|
One technique sometimes used with blocking sockets is to use a system call
|
|
(such as \fIselect()\fR, \fIpoll()\fR or equivalent) to determine when data is available
|
|
and then call \fIread()\fR to read the data. The equivalent with BIOs (that is call
|
|
\&\fIselect()\fR on the underlying I/O structure and then call \fIBIO_read()\fR to
|
|
read the data) should \fBnot\fR be used because a single call to \fIBIO_read()\fR
|
|
can cause several reads (and writes in the case of \s-1SSL\s0 BIOs) on the underlying
|
|
I/O structure and may block as a result. Instead \fIselect()\fR (or equivalent)
|
|
should be combined with non blocking I/O so successive reads will request
|
|
a retry instead of blocking.
|
|
.PP
|
|
See BIO_should_retry(3) for details of how to
|
|
determine the cause of a retry and other I/O issues.
|
|
.PP
|
|
If the \fIBIO_gets()\fR function is not supported by a \s-1BIO\s0 then it possible to
|
|
work around this by adding a buffering \s-1BIO\s0 BIO_f_buffer(3)
|
|
to the chain.
|
|
.SH "SEE ALSO"
|
|
.IX Header "SEE ALSO"
|
|
BIO_should_retry(3)
|
|
.PP
|
|
\&\s-1TBA\s0
|