Current Path :
/
opt
/
alt
/
openssl11
/
share
/
man
/
man3
/
Or
Select Your Path :
Upload File :
New :
File
Dir
//opt/alt/openssl11/share/man/man3/BIO_get_mem_ptr.3ssl
.\" 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 3" .TH BIO_S_MEM 3 "2023-09-11" "1.1.1w" "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_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_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 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 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. .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 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. .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 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 \s-1BIO\s0 created with \fIBIO_new_secmem()\fR will give undefined results, including perhaps a program crash. .PP Switching the 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 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. .SH "BUGS" .IX Header "BUGS" There should be an option to set the maximum size of a memory \s-1BIO.\s0 .SH "RETURN VALUES" .IX Header "RETURN VALUES" \&\fIBIO_s_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 .SH "COPYRIGHT" .IX Header "COPYRIGHT" Copyright 2000\-2019 The OpenSSL Project Authors. All Rights Reserved. .PP Licensed under the OpenSSL license (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>.
