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diff --git a/secure/lib/libcrypto/man/man3/BIO_s_mem.3 b/secure/lib/libcrypto/man/man3/BIO_s_mem.3 new file mode 100644 index 000000000000..5809e2963fcc --- /dev/null +++ b/secure/lib/libcrypto/man/man3/BIO_s_mem.3 @@ -0,0 +1,320 @@ +.\" Automatically generated by Pod::Man 4.14 (Pod::Simple 3.42) +.\" +.\" 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++. 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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" +\&\fBBIO_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 +\&\fBBIO_s_secmem()\fR is like \fBBIO_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 \fBBIO_gets()\fR and \fBBIO_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 \fBBIO_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 +\&\fBBIO_eof()\fR is true if no data is in the \s-1BIO.\s0 +.PP +\&\fBBIO_ctrl_pending()\fR returns the number of bytes currently stored. +.PP +\&\fBBIO_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 +\&\fBBIO_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 \fBBIO_set_close()\fR. +.PP +\&\fBBIO_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 +\&\fBBIO_get_mem_ptr()\fR places the underlying \s-1BUF_MEM\s0 structure in *\fBpp\fR. It is +a macro. +.PP +\&\fBBIO_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 \fBBIO_set_mem_buf()\fR on a \s-1BIO\s0 created with \fBBIO_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 \fBBIO_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 \fBBIO_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 \fBBIO_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 \fBBIO_get_mem_ptr()\fR prior to a \fBBIO_reset()\fR call with +\&\s-1BIO_FLAGS_NONCLEAR_RST\s0 set has the same effect as a write operation. +.PP +Calling \fBBIO_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 "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" +\&\fBBIO_s_mem()\fR and \fBBIO_s_secmem()\fR return a valid memory \fB\s-1BIO_METHOD\s0\fR structure. +.PP +\&\fBBIO_set_mem_eof_return()\fR, \fBBIO_set_mem_buf()\fR and \fBBIO_get_mem_ptr()\fR +return 1 on success or a value which is less than or equal to 0 if an error occurred. +.PP +\&\fBBIO_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 +\&\fBBIO_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>. |