BIOctrl(3) OpenSSL BIOctrl(3)

NAME
       BIOctrl, BIOcallbackctrl, BIOptrctrl, BIOintctrl, BIOreset,
       BIOseek, BIOtell, BIOflush, BIOeof, BIOsetclose, BIOgetclose,
       BIOpending, BIOwpending, BIOctrlpending, BIOctrlwpending,
       BIOgetinfocallback, BIOsetinfocallback - BIO control operations

SYNOPSIS
        #include 

        long BIOctrl(BIO *bp,int cmd,long larg,void *parg);
        long BIOcallbackctrl(BIO *b, int cmd, void (*fp)(struct biost *, int, const char *, int, long, long));
        char * BIOptrctrl(BIO *bp,int cmd,long larg);
        long BIOintctrl(BIO *bp,int cmd,long larg,int iarg);

        int BIOreset(BIO *b);
        int BIOseek(BIO *b, int ofs);
        int BIOtell(BIO *b);
        int BIOflush(BIO *b);
        int BIOeof(BIO *b);
        int BIOsetclose(BIO *b,long flag);
        int BIOgetclose(BIO *b);
        int BIOpending(BIO *b);
        int BIOwpending(BIO *b);
        sizet BIOctrlpending(BIO *b);
        sizet BIOctrlwpending(BIO *b);

        int BIOgetinfocallback(BIO *b,bioinfocb **cbp);
        int BIOsetinfocallback(BIO *b,bioinfocb *cb);

        typedef void bioinfocb(BIO *b, int oper, const char *ptr, int arg1, long arg2, long arg3);

DESCRIPTION
       BIOctrl(), BIOcallbackctrl(), BIOptrctrl() and BIOintctrl() are
       BIO "control" operations taking arguments of various types.  These
       functions are not normally 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 BIOs manual page
       as well as any special features of the standard calls.

       BIOreset() 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.

       BIOseek() resets a file related BIO's (that is file descriptor and
       FILE BIOs) file position pointer to ooffss bytes from start of file.

       BIOtell() returns the current file position of a file related BIO.

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

       BIOeof() returns 1 if the BIO has read EOF, the precise meaning of
       "EOF" varies according to the BIO type.

       BIOsetclose() sets the BIO bb close flag to ffllaagg. ffllaagg can take the
       value BIOCLOSE or BIONOCLOSE. Typically BIOCLOSE is used in a
       source/sink BIO to indicate that the underlying I/O stream should be
       closed when the BIO is freed.

       BIOgetclose() returns the BIOs close flag.

       BIOpending(), BIOctrlpending(), BIOwpending() and
       BIOctrlwpending() return the number of pending characters in the BIOs
       read and write buffers.  Not all BIOs support these calls.
       BIOctrlpending() and BIOctrlwpending() return a sizet type and are
       functions, BIOpending() and BIOwpending() are macros which call
       BIOctrl().

RETURN VALUES
       BIOreset() 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.

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

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

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

       BIOsetclose() always returns 1.

       BIOgetclose() returns the close flag value: BIOCLOSE or BIONOCLOSE.

       BIOpending(), BIOctrlpending(), BIOwpending() and
       BIOctrlwpending() return the amount of pending data.

NNOOTTEESS
       BIOflush(), because it can write data may return 0 or -1 indicating
       that the call should be retried later in a similar manner to
       BIOwrite().  The BIOshouldretry() call should be used and
       appropriate action taken is the call fails.

       The return values of BIOpending() and BIOwpending() may 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 structures
       internal buffers but it is not possible to determine this in a portably
       way. For other types of BIO they may not be supported.

       Filter BIOs if they do not internally handle a particular BIOctrl()
       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
       BIOseek(), but this may still succeed if the chain ends in a FILE or
       file descriptor BIO.

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

BUGS
       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 BIOseek() on a file BIO for a successful operation.

SEE ALSO
       TBA



0.9.7l                            2000-09-18                       BIOctrl(3)