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  man pages->Tru64 Unix man pages -> BIO_set_info_callback (3)              



NAME    [Toc]    [Back]

       BIO_ctrl, BIO_callback_ctrl, BIO_ctrl_wpending, BIO_wpending,
 BIO_eof, BIO_flush, BIO_get_close, BIO_get_info_callback,
  BIO_set_info_callback,  BIO_int_ctrl,  BIO_pending,
       BIO_ptr_ctrl, BIO_reset, BIO_seek, BIO_set_close, BIO_tell
       - BIO control operations

SYNOPSIS    [Toc]    [Back]

       #include <openssl/bio.h>

       long BIO_ctrl(
               BIO *bp,
               int cmd,
               long larg,
               void *parg ); long BIO_callback_ctrl(
               BIO *b,
               int cmd,
               void (*fp)(struct bio_st *,
               const char *,
               long) ); char *    BIO_ptr_ctrl(
               BIO *bp,
               int cmd,
               long larg ); long BIO_int_ctrl(
               BIO *bp,
               int cmd,
               long larg,
               int iarg ); int BIO_reset(
               BIO *b ); int BIO_seek(
               BIO *b,
               int ofs ); int BIO_tell(
               BIO *b ); int BIO_flush(
               BIO *b ); int BIO_eof(
               BIO *b ); int BIO_set_close(
               BIO *b,
               long flag ); int BIO_get_close(
               BIO *b ); int BIO_pending(
               BIO *b ); int BIO_wpending(
               BIO *b ); size_t BIO_ctrl_pending(
               BIO *b ); size_t BIO_ctrl_wpending(
               BIO *b ); int BIO_get_info_callback(
               BIO *b,
               bio_info_cb **cbp ); int BIO_set_info_callback(
               BIO *b,
               bio_info_cb *cb ); typedef void bio_info_cb(
               BIO *b,
               int oper,
               const char *ptr,
               int arg1,
               long arg2,
               long arg3 );

DESCRIPTION    [Toc]    [Back]

       The  BIO_ctrl(),  BIO_callback_ctrl(), BIO_ptr_ctrl(), and
       BIO_int_ctrl() functions are BIO control operations taking
       arguments  of  various types. These functions are not usually
 called directly; various macros are used instead. The
       standard  macros are described below. Macros specific to a
       particular type of BIO are described in the specific BIO's
       reference  page,  as  well  as any special features of the
       standard calls.

       The BIO_reset()function typically resets  a  BIO  to  some
       initial state. In the case of file related BIOs, for example,
 it rewinds the file pointer to the start of the file.

       The  BIO_seek()  function resets a file related BIO's (its
       file descriptor and FILE BIOs) file  position  pointer  to
       ofs bytes from start of file.

       The  BIO_tell() function returns the current file position
       of a file related BIO.

       The BIO_flush() function normally writes  out  any  internally
  buffered  data,  in some cases it is used to signal
       EOF and that no more data will be written.

       The BIO_eof() function returns 1 if the BIO has read  EOF,
       the  precise  meaning  of  EOF varies according to the BIO

       The BIO_set_close() function sets the BIO b close flag  to
       flag.   flag  can take the value BIO_CLOSE or BIO_NOCLOSE.
       Typically BIO_CLOSE is used in a source/sink BIO to  indicate
  that the underlying I/O stream should be closed when
       the BIO is freed.

       The BIO_get_close() function returns the BIO's close flag.

       The BIO_pending(), BIO_ctrl_pending(), BIO_wpending(), and
       BIO_ctrl_wpending() functions return the number of pending
       characters  in  the BIO's read and write buffers.  Not all
       BIOs  support  these  calls.  The  BIO_ctrl_pending()  and
       BIO_ctrl_wpending() functions return a size_t type and are
       functions.  BIO_pending() and  BIO_wpending()  are  macros
       which call BIO_ctrl().

NOTES    [Toc]    [Back]

       The BIO_flush() function, because it can write data, might
       return 0 or -1 indicating that the call should be  retried
       later   in   a   similar   manner   to  BIO_write().   The
       BIO_should_retry() function should be used and appropriate
       action taken if the call fails.

       The  return values of the BIO_pending() and BIO_wpending()
       functions might not reliably determine the amount of pending
  data in all cases. For example, in the case of a file
       BIO some data may be available  in  the  FILE  structure's
       internal  buffers but it is not possible to determine this
       in a portably way. For other types of BIO they  might  not
       be supported.

       Filter BIOs, if they do not internally handle a particular
       BIO_ctrl() operation, usually pass the  operation  to  the
       next  BIO  in the chain. This often means there is no need
       to locate the required BIO for a particular operation.  It
       can  be  called  on  a  chain and it will be automatically
       passed to the relevant BIO. However, this can cause  unexpected
 results. For example, no current filter BIOs implement
 BIO_seek(), but this might still succeed if the chain
       ends in a FILE or file descriptor BIO.

       Source/sink  BIOs  return a 0 if they do not recognize the
       BIO_ctrl() operation.

RESTRICTIONS    [Toc]    [Back]

       Some of the return values are ambiguous and care should be
       taken.  In  particular a return value of 0 can be returned
       if an operation is not supported, if an error occurred, if
       EOF  has not been reached, and - in the case of BIO_seek()
       - on a file BIO for a successful operation.

RETURN VALUES    [Toc]    [Back]

       BIO_reset() normally returns 1 for success and 0 or -1 for
       failure.  File  BIOs  are  an exception, they return 0 for
       success and -1 for failure.

       BIO_seek() and BIO_tell() both  return  the  current  file
       position  on  success and -1 for failure, except file BIOs
       which for BIO_seek() always return 0 for  success  and  -1
       for failure.

       BIO_flush() returns 1 for success and 0 or -1 for failure.

       BIO_eof() returns 1 if EOF has been reached 0 otherwise.

       BIO_set_close() always returns 1.

       BIO_get_close() returns the close flag value: BIO_CLOSE or

       The BIO_pending(), BIO_ctrl_pending(), BIO_wpending(), and
       BIO_ctrl_wpending() functions return the amount of pending

SEE ALSO    [Toc]    [Back]


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