Re-install OpenSSL 0.9.8k

[msysgit.git] / ssl / man / man3 / BIO_s_mem.3

.\" Automatically generated by Pod::Man v1.37, Pod::Parser v1.32
.\"
.\" 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 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.
.    \" 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_s_mem 3"
.TH BIO_s_mem 3 "2009-07-23" "0.9.8k" "OpenSSL"
.SH "NAME"
BIO_s_mem, BIO_set_mem_eof_return, BIO_get_mem_data, BIO_set_mem_buf,
BIO_get_mem_ptr, BIO_new_mem_buf \- memory BIO
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/bio.h>
.Ve
.PP
.Vb 1
\& BIO_METHOD *   BIO_s_mem(void);
.Ve
.PP
.Vb 4
\& BIO_set_mem_eof_return(BIO *b,int v)
\& long BIO_get_mem_data(BIO *b, char **pp)
\& BIO_set_mem_buf(BIO *b,BUF_MEM *bm,int c)
\& BIO_get_mem_ptr(BIO *b,BUF_MEM **pp)
.Ve
.PP
.Vb 1
\& BIO *BIO_new_mem_buf(void *buf, int len);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\fIBIO_s_mem()\fR return the memory \s-1BIO\s0 method function. 
.PP
A memory \s-1BIO\s0 is a source/sink \s-1BIO\s0 which uses memory for its I/O. Data
written to a memory \s-1BIO\s0 is stored in a \s-1BUF_MEM\s0 structure which is extended
as appropriate to accommodate the stored data.
.PP
Any data written to a memory \s-1BIO\s0 can be recalled by reading from it.
Unless the memory \s-1BIO\s0 is read only any data read from it is deleted from
the \s-1BIO\s0.
.PP
Memory BIOs support \fIBIO_gets()\fR and \fIBIO_puts()\fR.
.PP
If the \s-1BIO_CLOSE\s0 flag is set when a memory \s-1BIO\s0 is freed then the underlying
\&\s-1BUF_MEM\s0 structure is also freed.
.PP
Calling \fIBIO_reset()\fR on a read write memory \s-1BIO\s0 clears any data in it. On a
read only \s-1BIO\s0 it restores the \s-1BIO\s0 to its original state and the read only
data can be read again.
.PP
\&\fIBIO_eof()\fR is true if no data is in the \s-1BIO\s0.
.PP
\&\fIBIO_ctrl_pending()\fR returns the number of bytes currently stored.
.PP
\&\fIBIO_set_mem_eof_return()\fR sets the behaviour of memory \s-1BIO\s0 \fBb\fR when it is
empty. If the \fBv\fR is zero then an empty memory \s-1BIO\s0 will return \s-1EOF\s0 (that is
it will return zero and BIO_should_retry(b) will be false. If \fBv\fR is non
zero then it will return \fBv\fR when it is empty and it will set the read retry
flag (that is BIO_read_retry(b) is true). To avoid ambiguity with a normal
positive return value \fBv\fR should be set to a negative value, typically \-1.
.PP
\&\fIBIO_get_mem_data()\fR sets \fBpp\fR to a pointer to the start of the memory BIOs data
and returns the total amount of data available. It is implemented as a macro.
.PP
\&\fIBIO_set_mem_buf()\fR sets the internal \s-1BUF_MEM\s0 structure to \fBbm\fR and sets the
close flag to \fBc\fR, that is \fBc\fR should be either \s-1BIO_CLOSE\s0 or \s-1BIO_NOCLOSE\s0.
It is a macro.
.PP
\&\fIBIO_get_mem_ptr()\fR places the underlying \s-1BUF_MEM\s0 structure in \fBpp\fR. It is
a macro.
.PP
\&\fIBIO_new_mem_buf()\fR creates a memory \s-1BIO\s0 using \fBlen\fR bytes of data at \fBbuf\fR,
if \fBlen\fR is \-1 then the \fBbuf\fR is assumed to be null terminated and its
length is determined by \fBstrlen\fR. The \s-1BIO\s0 is set to a read only state and
as a result cannot be written to. This is useful when some data needs to be
made available from a static area of memory in the form of a \s-1BIO\s0. The
supplied data is read directly from the supplied buffer: it is \fBnot\fR copied
first, so the supplied area of memory must be unchanged until the \s-1BIO\s0 is freed.
.SH "NOTES"
.IX Header "NOTES"
Writes to memory BIOs will always succeed if memory is available: that is
their size can grow indefinitely.
.PP
Every read from a read write memory \s-1BIO\s0 will remove the data just read with
an internal copy operation, if a \s-1BIO\s0 contains a lots of data and it is
read in small chunks the operation can be very slow. The use of a read only
memory \s-1BIO\s0 avoids this problem. If the \s-1BIO\s0 must be read write then adding
a buffering \s-1BIO\s0 to the chain will speed up the process.
.SH "BUGS"
.IX Header "BUGS"
There should be an option to set the maximum size of a memory \s-1BIO\s0.
.PP
There should be a way to \*(L"rewind\*(R" a read write \s-1BIO\s0 without destroying
its contents.
.PP
The copying operation should not occur after every small read of a large \s-1BIO\s0
to improve efficiency.
.SH "EXAMPLE"
.IX Header "EXAMPLE"
Create a memory \s-1BIO\s0 and write some data to it:
.PP
.Vb 2
\& BIO *mem = BIO_new(BIO_s_mem());
\& BIO_puts(mem, "Hello World\en");
.Ve
.PP
Create a read only memory \s-1BIO:\s0
.PP
.Vb 3
\& char data[] = "Hello World";
\& BIO *mem;
\& mem = BIO_new_mem_buf(data, -1);
.Ve
.PP
Extract the \s-1BUF_MEM\s0 structure from a memory \s-1BIO\s0 and then free up the \s-1BIO:\s0
.PP
.Vb 4
\& BUF_MEM *bptr;
\& BIO_get_mem_ptr(mem, &bptr);
\& BIO_set_close(mem, BIO_NOCLOSE); /* So BIO_free() leaves BUF_MEM alone */
\& BIO_free(mem);
.Ve
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\s-1TBA\s0