BIO_s_mem(3)                        OpenSSL                       BIO_s_mem(3)


NNAAMMEE
       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

SSYYNNOOPPSSIISS
        #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);

DDEESSCCRRIIPPTTIIOONN
       _B_I_O___s___m_e_m_(_) 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 _B_I_O___g_e_t_s_(_) and _B_I_O___p_u_t_s_(_).

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

       Calling _B_I_O___r_e_s_e_t_(_) 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.

       _B_I_O___e_o_f_(_) is true if no data is in the BIO.

       _B_I_O___c_t_r_l___p_e_n_d_i_n_g_(_) returns the number of bytes currently stored.

       _B_I_O___s_e_t___m_e_m___e_o_f___r_e_t_u_r_n_(_) sets the behaviour of memory BIO bb when it is
       empty. If the v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v is
       non zero then it will return v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v should be set to a negative
       value, typically -1.

       _B_I_O___g_e_t___m_e_m___d_a_t_a_(_) sets pppp 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.

       _B_I_O___s_e_t___m_e_m___b_u_f_(_) sets the internal BUF_MEM structure to bbmm and sets
       the close flag to cc, that is cc should be either BIO_CLOSE or
       BIO_NOCLOSE.  It is a macro.

       _B_I_O___g_e_t___m_e_m___p_t_r_(_) places the underlying BUF_MEM structure in pppp. It is
       a macro.

       _B_I_O___n_e_w___m_e_m___b_u_f_(_) creates a memory BIO using lleenn bytes of data at bbuuff,
       if lleenn is -1 then the bbuuff is assumed to be null terminated and its
       length is determined by ssttrrlleenn. 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 nnoott
       copied first, so the supplied area of memory must be unchanged until
       the BIO is freed.

NNOOTTEESS
       Writes to memory BIOs will always succeed if memory is available: that
       is 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 a lot of 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.

BBUUGGSS
       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.

       The copying operation should not occur after every small read of a
       large BIO to improve efficiency.

EEXXAAMMPPLLEE
       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);

SSEEEE AALLSSOO
       TBA


1.0.1u                            2016-09-22                      BIO_s_mem(3)