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BIO_s_mem(3)							  BIO_s_mem(3)

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

SYNOPSIS
       #include <openssl/bio.h>

       BIO_METHOD *   BIO_s_mem(
	       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(
	       void *buf,
	       int len );

DESCRIPTION
       BIO_s_mem() return the memory BIO method function.

       A memory BIO is a source/sink BIO which uses memory for its  I/O.  Data
       written	to  a  memory  BIO  is	stored in a BUF_MEM structure which is
       extended as appropriate to accommodate the stored data.

       Any data written to a memory BIO can be recalled by  reading  from  it.
       Unless  the  memory  BIO	 is read only any data read from it is deleted
       from the BIO.

       Memory BIOs support BIO_gets() and BIO_puts().

       If the BIO_CLOSE flag is set when a memory BIO is freed then the underÔÇÉ
       lying BUF_MEM structure is also freed.

       Calling	BIO_reset()  on a read write memory BIO clears any data in it.
       On a read only BIO it restores the BIO to its original  state  and  the
       read only data can be read again.

       BIO_eof() is true if no data is in the BIO.

       BIO_ctrl_pending() returns the number of bytes currently stored.

       BIO_set_mem_eof_return()	 sets the behaviour of memory BIO b when it is
       empty. If the v is zero then an empty memory BIO will return EOF	 (that
       is  it  will return zero and BIO_should_retry(b) will be false. If v is
       non zero then it will return v 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 v  should  be  set  to  a  negative
       value, typically -1.

       BIO_get_mem_data() sets pp 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.

       BIO_set_mem_buf()  sets	the  internal BUF_MEM structure to bm and sets
       the close  flag	to  c,	that  is  c  should  be	 either	 BIO_CLOSE  or
       BIO_NOCLOSE. It is a macro.

       BIO_get_mem_ptr()  places the underlying BUF_MEM structure in pp. It is
       a macro.

       BIO_new_mem_buf() creates a memory BIO using len bytes of data at  buf.
       If  len	is  -1	then  the buf is assumed to be null terminated and its
       length is determined by strlen. The BIO 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 BIO.
       The  supplied data is read directly from the supplied buffer. It is not
       copied first. So the supplied area of memory must  be  unchanged	 until
       the BIO is freed.

NOTES
       Writes to memory BIOs will always succeed if memory is available. Their
       size can grow indefinitely.

       Every read from a read-write memory BIO will remove the data just  read
       with  an internal copy operation. If a BIO contains much data and it is
       read in small chunks, the operation can be very	slow.  The  use	 of  a
       read-only-memory	 BIO  avoids  this  problem.  If the BIO must be read-
       write, then adding a buffering BIO to  the  chain  will	speed  up  the
       process.

RESTRICTIONS
       There should be an option to set the maximum size of a memory BIO.

       There should be a way to rewind a read-write BIO without destroying its
       contents.

       To improve efficiency, the copying operation  should  not  occur	 after
       every small read of a large BIO.

EXAMPLES
       Create	a   memory  BIO	 and  write  some  data	 to  it:  BIO  *mem  =
       BIO_new(BIO_s_mem()); BIO_puts(mem, "Hello World\n");

       Create a read only memory BIO: char data[] = "Hello World";  BIO	 *mem;
       mem = BIO_new_mem_buf(data, -1);

       Extract	the  BUF_MEM  structure from a memory BIO and then free up the
       BIO: 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);

SEE ALSO
       TBA

								  BIO_s_mem(3)
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