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BIO(3)		      DragonFly Library Functions Manual		BIO(3)


NAME

     BIO -- I/O abstraction


SYNOPSIS

     #include <openssl/bio.h>


DESCRIPTION

     A BIO is an I/O abstraction, it hides many of the underlying I/O details
     from an application.  If an application uses a BIO for its I/O, it can
     transparently handle SSL connections, unencrypted network connections and
     file I/O.

     There are two types of BIO, a source/sink BIO and a filter BIO.

     As its name implies, a source/sink BIO is a source and/or sink of data,
     examples include a socket BIO and a file BIO.

     A filter BIO takes data from one BIO and passes it through to another, or
     to the application.  The data may be left unmodified (for example a mes-
     sage digest BIO) or translated (for example an encryption BIO).  The
     effect of a filter BIO may change according to the I/O operation it is
     performing: for example an encryption BIO will encrypt data if it is
     being written to and decrypt data if it is being read from.

     BIOs can be joined together to form a chain (a single BIO is a chain with
     one component).  A chain normally consist of one source/sink BIO and one
     or more filter BIOs.  Data read from or written to the first BIO then
     traverses the chain to the end (normally a source/sink BIO).


SEE ALSO

     BIO_ctrl(3), BIO_f_base64(3), BIO_f_buffer(3), BIO_f_cipher(3),
     BIO_f_md(3), BIO_f_null(3), BIO_f_ssl(3), BIO_find_type(3), BIO_new(3),
     BIO_new_bio_pair(3), BIO_push(3), BIO_read(3), BIO_s_accept(3),
     BIO_s_bio(3), BIO_s_connect(3), BIO_s_fd(3), BIO_s_file(3), BIO_s_mem(3),
     BIO_s_null(3), BIO_s_socket(3), BIO_set_callback(3), BIO_should_retry(3)

DragonFly 4.7			 July 17, 2014			 DragonFly 4.7
BIO_s_fd(3)                         OpenSSL                        BIO_s_fd(3)


NAME

       BIO_s_fd, BIO_set_fd, BIO_get_fd, BIO_new_fd - file descriptor BIO


SYNOPSIS

        #include <openssl/bio.h>

        BIO_METHOD *   BIO_s_fd(void);

        #define BIO_set_fd(b,fd,c)     BIO_int_ctrl(b,BIO_C_SET_FD,c,fd)
        #define BIO_get_fd(b,c)        BIO_ctrl(b,BIO_C_GET_FD,0,(char *)c)

        BIO *BIO_new_fd(int fd, int close_flag);


DESCRIPTION

       BIO_s_fd() returns the file descriptor BIO method. This is a wrapper
       round the platforms file descriptor routines such as read() and
       write().

       BIO_read() and BIO_write() read or write the underlying descriptor.
       BIO_puts() is supported but BIO_gets() is not.

       If the close flag is set then then close() is called on the underlying
       file descriptor when the BIO is freed.

       BIO_reset() attempts to change the file pointer to the start of file
       using lseek(fd, 0, 0).

       BIO_seek() sets the file pointer to position ofs from start of file
       using lseek(fd, ofs, 0).

       BIO_tell() returns the current file position by calling lseek(fd, 0,
       1).

       BIO_set_fd() sets the file descriptor of BIO b to fd and the close flag
       to c.

       BIO_get_fd() places the file descriptor in c if it is not NULL, it also
       returns the file descriptor. If c is not NULL it should be of type (int
       *).

       BIO_new_fd() returns a file descriptor BIO using fd and close_flag.


NOTES

       The behaviour of BIO_read() and BIO_write() depends on the behavior of
       the platforms read() and write() calls on the descriptor. If the
       underlying file descriptor is in a non blocking mode then the BIO will
       behave in the manner described in the BIO_read(3) and
       BIO_should_retry(3) manual pages.

       File descriptor BIOs should not be used for socket I/O. Use socket BIOs
       instead.


RETURN VALUES

       BIO_s_fd() returns the file descriptor BIO method.

       BIO_reset() returns zero for success and -1 if an error occurred.
       BIO_seek() and BIO_tell() return the current file position or -1 is an
       error occurred. These values reflect the underlying lseek() behaviour.

       BIO_set_fd() always returns 1.

       BIO_get_fd() returns the file descriptor or -1 if the BIO has not been
       initialized.

       BIO_new_fd() returns the newly allocated BIO or NULL is an error
       occurred.


EXAMPLE

       This is a file descriptor BIO version of "Hello World":

        BIO *out;
        out = BIO_new_fd(fileno(stdout), BIO_NOCLOSE);
        BIO_printf(out, "Hello World\n");
        BIO_free(out);


SEE ALSO

       BIO_seek(3), BIO_tell(3), BIO_reset(3), BIO_read(3), BIO_write(3),
       BIO_puts(3), BIO_gets(3), BIO_printf(3), BIO_set_close(3),
       BIO_get_close(3)

1.0.2h                            2016-05-03                       BIO_s_fd(3)

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