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NAME

       BIO_s_fd, BIO_set_fd, BIO_get_fd, BIO_new_fd - file descriptor BIO

SYNOPSIS

        #include <openssl/bio.h>

        const BIO_METHOD *BIO_s_fd(void);

        int BIO_set_fd(BIO *b, int fd, int c);
        int BIO_get_fd(BIO *b, int *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_ex() and BIO_write_ex() read or write the underlying descriptor.  BIO_puts() is
       supported but BIO_gets() is not.

       If the close flag is set 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 such as by using
       lseek(fd, 0, 0).

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

       BIO_tell() returns the current file position such as 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.

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

NOTES

       The behaviour of BIO_read_ex() and BIO_write_ex() 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_ex(3) and
       BIO_should_retry(3) manual pages.

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

       BIO_set_fd() and BIO_get_fd() are implemented as macros.

RETURN VALUES

       BIO_s_fd() returns the file descriptor BIO method.

       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_ex(3), BIO_write_ex(3), BIO_puts(3),
       BIO_gets(3), BIO_printf(3), BIO_set_close(3), BIO_get_close(3)

COPYRIGHT

       Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the OpenSSL license (the "License").  You may not use this file except in
       compliance with the License.  You can obtain a copy in the file LICENSE in the source
       distribution or at <https://www.openssl.org/source/license.html>.