BIOread(3) OpenSSL BIOread(3)

NAME
       BIOread, BIOwrite, BIOgets, BIOputs - BIO I/O functions

SYNOPSIS
        #include 

        int    BIOread(BIO *b, void *buf, int len);
        int    BIOgets(BIO *b,char *buf, int size);
        int    BIOwrite(BIO *b, const void *buf, int len);
        int    BIOputs(BIO *b,const char *buf);

DESCRIPTION
       BIOread() attempts to read lleenn bytes from BIO bb and places the data in
       bbuuff.

       BIOgets() performs the BIOs "gets" operation and places the data in
       bbuuff. Usually this operation will attempt to read a line of data from
       the BIO of maximum length lleenn. There are exceptions to this however,
       for example BIOgets() on a digest BIO will calculate and return the
       digest and other BIOs may not support BIOgets() at all.

       BIOwrite() attempts to write lleenn bytes from bbuuff to BIO bb.

       BIOputs() attempts to write a null terminated string bbuuff to BIO bb

RETURN VALUES
       All these functions return either the amount of data successfully read
       or written (if the return value is positive) or that no data was
       successfully read or written if the result is 0 or -1. If the return
       value is -2 then the operation is not implemented in the specific BIO
       type.

NNOOTTEESS
       A 0 or -1 return is not necessarily an indication of an error. In
       particular when the source/sink is non-blocking or of a certain type it
       may merely be an indication that no data is currently available and
       that the application should retry the operation later.

       One technique sometimes used with blocking sockets is to use a system
       call (such as select(), poll() or equivalent) to determine when data is
       available and then call read() to read the data. The equivalent with
       BIOs (that is call select() on the underlying I/O structure and then
       call BIOread() to read the data) should nnoott be used because a single
       call to BIOread() can cause several reads (and writes in the case of
       SSL BIOs) on the underlying I/O structure and may block as a result.
       Instead select() (or equivalent) should be combined with non blocking
       I/O so successive reads will request a retry instead of blocking.

       See BIOshouldretry(3) for details of how to determine the cause of a
       retry and other I/O issues.

       If the BIOgets() function is not supported by a BIO then it possible
       to work around this by adding a buffering BIO BIOfbuffer(3) to the
       chain.

SEE ALSO
       BIOshouldretry(3)

       TBA



0.9.7l                            2000-09-16                       BIOread(3)