BIO_s_fd.pod revision 337982 
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 BIO_METHOD *	BIO_s_fd(void);
12
13 #define BIO_set_fd(b,fd,c)	BIO_int_ctrl(b,BIO_C_SET_FD,c,fd)
14 #define BIO_get_fd(b,c)	BIO_ctrl(b,BIO_C_GET_FD,0,(char *)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() and BIO_write() read or write the underlying descriptor.
24BIO_puts() is supported but BIO_gets() is not.
25
26If the close flag is set then 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
30using lseek(fd, 0, 0).
31
32BIO_seek() sets the file pointer to position B<ofs> from start of file
33using lseek(fd, ofs, 0).
34
35BIO_tell() returns the current file position by calling lseek(fd, 0, 1).
36
37BIO_set_fd() sets the file descriptor of BIO B<b> to B<fd> and the close
38flag to B<c>.
39
40BIO_get_fd() places the file descriptor in B<c> if it is not NULL, it also
41returns the file descriptor. If B<c> is not NULL it should be of type
42(int *).
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() and BIO_write() 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(3)|BIO_read(3)> and L<BIO_should_retry(3)|BIO_should_retry(3)>
52manual pages.
53
54File descriptor BIOs should not be used for socket I/O. Use socket BIOs
55instead.
56
57=head1 RETURN VALUES
58
59BIO_s_fd() returns the file descriptor BIO method.
60
61BIO_reset() returns zero for success and -1 if an error occurred.
62BIO_seek() and BIO_tell() return the current file position or -1
63if an error occurred. These values reflect the underlying lseek()
64behaviour.
65
66BIO_set_fd() always returns 1.
67
68BIO_get_fd() returns the file descriptor or -1 if the BIO has not
69been initialized.
70
71BIO_new_fd() returns the newly allocated BIO or NULL is an error
72occurred.
73
74=head1 EXAMPLE
75
76This is a file descriptor BIO version of "Hello World":
77
78 BIO *out;
79 out = BIO_new_fd(fileno(stdout), BIO_NOCLOSE);
80 BIO_printf(out, "Hello World\n");
81 BIO_free(out);
82
83=head1 SEE ALSO
84
85L<BIO_seek(3)|BIO_seek(3)>, L<BIO_tell(3)|BIO_tell(3)>,
86L<BIO_reset(3)|BIO_reset(3)>, L<BIO_read(3)|BIO_read(3)>,
87L<BIO_write(3)|BIO_write(3)>, L<BIO_puts(3)|BIO_puts(3)>,
88L<BIO_gets(3)|BIO_gets(3)>, L<BIO_printf(3)|BIO_printf(3)>,
89L<BIO_set_close(3)|BIO_set_close(3)>, L<BIO_get_close(3)|BIO_get_close(3)>
90