349 lines
14 KiB
Plaintext
349 lines
14 KiB
Plaintext
.\" Automatically generated by Pod::Man 2.27 (Pod::Simple 3.28)
|
|
.\"
|
|
.\" 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 turned on, 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_S_MEM 3ossl"
|
|
.TH BIO_S_MEM 3ossl "2024-01-30" "3.2.1" "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_s_secmem, BIO_s_dgram_mem,
|
|
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>
|
|
\&
|
|
\& const BIO_METHOD *BIO_s_mem(void);
|
|
\& const BIO_METHOD *BIO_s_dgram_mem(void);
|
|
\& const BIO_METHOD *BIO_s_secmem(void);
|
|
\&
|
|
\& 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);
|
|
\&
|
|
\& BIO *BIO_new_mem_buf(const void *buf, int len);
|
|
.Ve
|
|
.SH "DESCRIPTION"
|
|
.IX Header "DESCRIPTION"
|
|
\&\fIBIO_s_mem()\fR returns 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
|
|
\&\fIBIO_s_secmem()\fR is like \fIBIO_s_mem()\fR except that the secure heap is used
|
|
for buffer storage.
|
|
.PP
|
|
\&\fIBIO_s_dgram_mem()\fR is a memory \s-1BIO\s0 that respects datagram semantics. A single
|
|
call to \fIBIO_write\fR\|(3) will write a single datagram to the memory \s-1BIO. A\s0
|
|
subsequent call to \fIBIO_read\fR\|(3) will read the data in that datagram. The
|
|
\&\fIBIO_read\fR\|(3) call will never return more data than was written in the original
|
|
\&\fIBIO_write\fR\|(3) call even if there were subsequent \fIBIO_write\fR\|(3) calls that
|
|
wrote more datagrams. Each successive call to \fIBIO_read\fR\|(3) will read the next
|
|
datagram. If a \fIBIO_read\fR\|(3) call supplies a read buffer that is smaller than
|
|
the size of the datagram, then the read buffer will be completely filled and the
|
|
remaining data from the datagram will be discarded.
|
|
.PP
|
|
It is not possible to write a zero length datagram. Calling \fIBIO_write\fR\|(3) in
|
|
this case will return 0 and no datagrams will be written. Calling \fIBIO_read\fR\|(3)
|
|
when there are no datagrams in the \s-1BIO\s0 to read will return a negative result and
|
|
the \*(L"retry\*(R" flags will be set (i.e. calling \fIBIO_should_retry\fR\|(3) will return
|
|
true). A datagram mem \s-1BIO\s0 will never return true from \fIBIO_eof\fR\|(3).
|
|
.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 except \fIBIO_s_dgram_mem()\fR support \fIBIO_gets()\fR and \fIBIO_puts()\fR.
|
|
.PP
|
|
\&\fIBIO_s_dgram_mem()\fR supports \fIBIO_sendmmsg\fR\|(3) and \fIBIO_recvmmsg\fR\|(3) calls
|
|
and calls related to \fB\s-1BIO_ADDR\s0\fR and \s-1MTU\s0 handling similarly to the
|
|
\&\fIBIO_s_dgram_pair\fR\|(3).
|
|
.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 if the
|
|
flag \s-1BIO_FLAGS_NONCLEAR_RST\s0 is not set, otherwise it just restores the read
|
|
pointer to the state it was just after the last write was performed and the
|
|
data can be read again. On a read only \s-1BIO\s0 it similarly 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.
|
|
Calling this macro will fail for datagram mem BIOs.
|
|
.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.
|
|
Note the pointer returned by this call is informative, no transfer of ownership
|
|
of this memory is implied. See notes on \fIBIO_set_close()\fR.
|
|
.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 nul 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.
|
|
.PP
|
|
All of the five functions described above return an error with
|
|
\&\fIBIO_s_dgram_mem()\fR.
|
|
.SH "NOTES"
|
|
.IX Header "NOTES"
|
|
Writes to memory BIOs will always succeed if memory is available: that is
|
|
their size can grow indefinitely. An exception is \fIBIO_s_dgram_mem()\fR when
|
|
\&\fIBIO_set_write_buf_size\fR\|(3) is called on it. In such case the write buffer
|
|
size will be fixed and any writes that would overflow the buffer will return
|
|
an error.
|
|
.PP
|
|
Every write after partial read (not all data in the memory buffer was read)
|
|
to a read write memory \s-1BIO\s0 will have to move the unread data with an internal
|
|
copy operation, if a \s-1BIO\s0 contains a lot of data and it is read in small
|
|
chunks intertwined with writes the operation can be very slow. Adding
|
|
a buffering \s-1BIO\s0 to the chain can speed up the process.
|
|
.PP
|
|
Calling \fIBIO_set_mem_buf()\fR on a secmem or dgram \s-1BIO\s0 will give undefined results,
|
|
including perhaps a program crash.
|
|
.PP
|
|
Switching a memory \s-1BIO\s0 from read write to read only is not supported and
|
|
can give undefined results including a program crash. There are two notable
|
|
exceptions to the rule. The first one is to assign a static memory buffer
|
|
immediately after \s-1BIO\s0 creation and set the \s-1BIO\s0 as read only.
|
|
.PP
|
|
The other supported sequence is to start with a read write \s-1BIO\s0 then temporarily
|
|
switch it to read only and call \fIBIO_reset()\fR on the read only \s-1BIO\s0 immediately
|
|
before switching it back to read write. Before the \s-1BIO\s0 is freed it must be
|
|
switched back to the read write mode.
|
|
.PP
|
|
Calling \fIBIO_get_mem_ptr()\fR on read only \s-1BIO\s0 will return a \s-1BUF_MEM\s0 that
|
|
contains only the remaining data to be read. If the close status of the
|
|
\&\s-1BIO\s0 is set to \s-1BIO_NOCLOSE,\s0 before freeing the \s-1BUF_MEM\s0 the data pointer
|
|
in it must be set to \s-1NULL\s0 as the data pointer does not point to an
|
|
allocated memory.
|
|
.PP
|
|
Calling \fIBIO_reset()\fR on a read write memory \s-1BIO\s0 with \s-1BIO_FLAGS_NONCLEAR_RST\s0
|
|
flag set can have unexpected outcome when the reads and writes to the
|
|
\&\s-1BIO\s0 are intertwined. As documented above the \s-1BIO\s0 will be reset to the
|
|
state after the last completed write operation. The effects of reads
|
|
preceding that write operation cannot be undone.
|
|
.PP
|
|
Calling \fIBIO_get_mem_ptr()\fR prior to a \fIBIO_reset()\fR call with
|
|
\&\s-1BIO_FLAGS_NONCLEAR_RST\s0 set has the same effect as a write operation.
|
|
.PP
|
|
Calling \fIBIO_set_close()\fR with \s-1BIO_NOCLOSE\s0 orphans the \s-1BUF_MEM\s0 internal to the
|
|
\&\s-1BIO,\s0 _not_ its actual data buffer. See the examples section for the proper
|
|
method for claiming ownership of the data pointer for a deferred free operation.
|
|
.SH "RETURN VALUES"
|
|
.IX Header "RETURN VALUES"
|
|
\&\fIBIO_s_mem()\fR, \fIBIO_s_dgram_mem()\fR and \fIBIO_s_secmem()\fR return a valid memory
|
|
\&\fB\s-1BIO_METHOD\s0\fR structure.
|
|
.PP
|
|
\&\fIBIO_set_mem_eof_return()\fR, \fIBIO_set_mem_buf()\fR and \fIBIO_get_mem_ptr()\fR
|
|
return 1 on success or a value which is less than or equal to 0 if an error occurred.
|
|
.PP
|
|
\&\fIBIO_get_mem_data()\fR returns the total number of bytes available on success,
|
|
0 if b is \s-1NULL,\s0 or a negative value in case of other errors.
|
|
.PP
|
|
\&\fIBIO_new_mem_buf()\fR returns a valid \fB\s-1BIO\s0\fR structure on success or \s-1NULL\s0 on error.
|
|
.SH "EXAMPLES"
|
|
.IX Header "EXAMPLES"
|
|
Create a memory \s-1BIO\s0 and write some data to it:
|
|
.PP
|
|
.Vb 1
|
|
\& 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 2
|
|
\& char data[] = "Hello World";
|
|
\& BIO *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 1
|
|
\& 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
|
|
.PP
|
|
Extract the \s-1BUF_MEM\s0 ptr, claim ownership of the internal data and free the \s-1BIO\s0
|
|
and \s-1BUF_MEM\s0 structure:
|
|
.PP
|
|
.Vb 2
|
|
\& BUF_MEM *bptr;
|
|
\& char *data;
|
|
\&
|
|
\& BIO_get_mem_data(bio, &data);
|
|
\& BIO_get_mem_ptr(bio, &bptr);
|
|
\& BIO_set_close(mem, BIO_NOCLOSE); /* So BIO_free orphans BUF_MEM */
|
|
\& BIO_free(bio);
|
|
\& bptr\->data = NULL; /* Tell BUF_MEM to orphan data */
|
|
\& BUF_MEM_free(bptr);
|
|
\& ...
|
|
\& free(data);
|
|
.Ve
|
|
.SH "COPYRIGHT"
|
|
.IX Header "COPYRIGHT"
|
|
Copyright 2000\-2023 The OpenSSL Project Authors. All Rights Reserved.
|
|
.PP
|
|
Licensed under the Apache License 2.0 (the \*(L"License\*(R"). You may not use
|
|
this file except in compliance with the License. You can obtain a copy
|
|
in the file \s-1LICENSE\s0 in the source distribution or at
|
|
<https://www.openssl.org/source/license.html>.
|