1BIO_S_FD(3)                         OpenSSL                        BIO_S_FD(3)
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NAME

6       BIO_s_fd, BIO_set_fd, BIO_get_fd, BIO_new_fd - file descriptor BIO
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SYNOPSIS

9        #include <openssl/bio.h>
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11        const BIO_METHOD *BIO_s_fd(void);
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13        int BIO_set_fd(BIO *b, int fd, int c);
14        int BIO_get_fd(BIO *b, int *c);
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16        BIO *BIO_new_fd(int fd, int close_flag);
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DESCRIPTION

19       BIO_s_fd() returns the file descriptor BIO method. This is a wrapper
20       round the platforms file descriptor routines such as read() and
21       write().
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23       BIO_read_ex() and BIO_write_ex() read or write the underlying
24       descriptor.  BIO_puts() is supported but BIO_gets() is not.
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26       If the close flag is set then close() is called on the underlying file
27       descriptor when the BIO is freed.
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29       BIO_reset() attempts to change the file pointer to the start of file
30       such as by using lseek(fd, 0, 0).
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32       BIO_seek() sets the file pointer to position ofs from start of file
33       such as by using lseek(fd, ofs, 0).
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35       BIO_tell() returns the current file position such as by calling
36       lseek(fd, 0, 1).
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38       BIO_set_fd() sets the file descriptor of BIO b to fd and the close flag
39       to c.
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41       BIO_get_fd() places the file descriptor in c if it is not NULL, it also
42       returns the file descriptor.
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44       BIO_new_fd() returns a file descriptor BIO using fd and close_flag.
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NOTES

47       The behaviour of BIO_read_ex() and BIO_write_ex() depends on the
48       behavior of the platforms read() and write() calls on the descriptor.
49       If the underlying file descriptor is in a non blocking mode then the
50       BIO will behave in the manner described in the BIO_read_ex(3) and
51       BIO_should_retry(3) manual pages.
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53       File descriptor BIOs should not be used for socket I/O. Use socket BIOs
54       instead.
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56       BIO_set_fd() and BIO_get_fd() are implemented as macros.
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RETURN VALUES

59       BIO_s_fd() returns the file descriptor BIO method.
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61       BIO_set_fd() always returns 1.
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63       BIO_get_fd() returns the file descriptor or -1 if the BIO has not been
64       initialized.
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66       BIO_new_fd() returns the newly allocated BIO or NULL is an error
67       occurred.
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EXAMPLES

70       This is a file descriptor BIO version of "Hello World":
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72        BIO *out;
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74        out = BIO_new_fd(fileno(stdout), BIO_NOCLOSE);
75        BIO_printf(out, "Hello World\n");
76        BIO_free(out);
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SEE ALSO

79       BIO_seek(3), BIO_tell(3), BIO_reset(3), BIO_read_ex(3),
80       BIO_write_ex(3), BIO_puts(3), BIO_gets(3), BIO_printf(3),
81       BIO_set_close(3), BIO_get_close(3)
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84       Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
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86       Licensed under the OpenSSL license (the "License").  You may not use
87       this file except in compliance with the License.  You can obtain a copy
88       in the file LICENSE in the source distribution or at
89       <https://www.openssl.org/source/license.html>.
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931.1.1q                            2023-07-20                       BIO_S_FD(3)
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