Updated: 2022/Sep/29

Please read Privacy Policy. It's for your privacy.

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

LIBRARY
       libcrypto, -lcrypto

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 of BIO b 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() returns 1 on success or <=0 for failure.

       BIO_get_fd() returns the file descriptor or -1 if the BIO has not been
       initialized. It also returns zero and negative values if other error
       occurs.

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

EXAMPLES
       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 2000-2021 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (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>.



3.0.12                            2023-05-07                       BIO_s_fd(3)