1=pod
2
3=head1 NAME
4
5BIO_s_fd, BIO_set_fd, BIO_get_fd, BIO_new_fd - file descriptor BIO
6
7=head1 SYNOPSIS
8
9 #include <openssl/bio.h>
10
11 const BIO_METHOD *BIO_s_fd(void);
12
13 int BIO_set_fd(BIO *b, int fd, int c);
14 int BIO_get_fd(BIO *b, int *c);
15
16 BIO *BIO_new_fd(int fd, int close_flag);
17
18=head1 DESCRIPTION
19
20BIO_s_fd() returns the file descriptor BIO method. This is a wrapper
21round the platforms file descriptor routines such as read() and write().
22
23BIO_read_ex() and BIO_write_ex() read or write the underlying descriptor.
24BIO_puts() is supported but BIO_gets() is not.
25
26If the close flag is set then close() is called on the underlying
27file descriptor when the BIO is freed.
28
29BIO_reset() attempts to change the file pointer to the start of file
30such as by using B<lseek(fd, 0, 0)>.
31
32BIO_seek() sets the file pointer to position B<ofs> from start of file
33such as by using B<lseek(fd, ofs, 0)>.
34
35BIO_tell() returns the current file position such as by calling
36B<lseek(fd, 0, 1)>.
37
38BIO_set_fd() sets the file descriptor of BIO B<b> to B<fd> and the close
39flag to B<c>.
40
41BIO_get_fd() places the file descriptor of BIO B<b> in B<c> if it is not NULL.
42It also returns the file descriptor.
43
44BIO_new_fd() returns a file descriptor BIO using B<fd> and B<close_flag>.
45
46=head1 NOTES
47
48The behaviour of BIO_read_ex() and BIO_write_ex() depends on the behavior of the
49platforms read() and write() calls on the descriptor. If the underlying
50file descriptor is in a non blocking mode then the BIO will behave in the
51manner described in the L<BIO_read_ex(3)> and L<BIO_should_retry(3)>
52manual pages.
53
54File descriptor BIOs should not be used for socket I/O. Use socket BIOs
55instead.
56
57BIO_set_fd() and BIO_get_fd() are implemented as macros.
58
59=head1 RETURN VALUES
60
61BIO_s_fd() returns the file descriptor BIO method.
62
63BIO_set_fd() returns 1 on success or <=0 for failure.
64
65BIO_get_fd() returns the file descriptor or -1 if the BIO has not
66been initialized. It also returns zero and negative values if other error occurs.
67
68BIO_new_fd() returns the newly allocated BIO or NULL is an error
69occurred.
70
71=head1 EXAMPLES
72
73This is a file descriptor BIO version of "Hello World":
74
75 BIO *out;
76
77 out = BIO_new_fd(fileno(stdout), BIO_NOCLOSE);
78 BIO_printf(out, "Hello World\n");
79 BIO_free(out);
80
81=head1 SEE ALSO
82
83L<BIO_seek(3)>, L<BIO_tell(3)>,
84L<BIO_reset(3)>, L<BIO_read_ex(3)>,
85L<BIO_write_ex(3)>, L<BIO_puts(3)>,
86L<BIO_gets(3)>, L<BIO_printf(3)>,
87L<BIO_set_close(3)>, L<BIO_get_close(3)>
88
89=head1 COPYRIGHT
90
91Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.
92
93Licensed under the Apache License 2.0 (the "License").  You may not use
94this file except in compliance with the License.  You can obtain a copy
95in the file LICENSE in the source distribution or at
96L<https://www.openssl.org/source/license.html>.
97
98=cut
99