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1 .\" $OpenBSD: BIO_s_fd.3,v 1.7 2018/03/20 19:33:16 schwarze Exp $
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51 .Dd $Mdocdate: March 20 2018 $
52 .Dt BIO_S_FD 3
53 .Os
54 .Sh NAME
55 .Nm BIO_s_fd ,
56 .Nm BIO_set_fd ,
57 .Nm BIO_get_fd ,
58 .Nm BIO_new_fd
59 .Nd file descriptor BIO
60 .Sh SYNOPSIS
61 .In openssl/bio.h
62 .Ft BIO_METHOD *
63 .Fo BIO_s_fd
64 .Fa "void"
65 .Fc
66 .Ft long
67 .Fo BIO_set_fd
68 .Fa "BIO *b"
69 .Fa "int fd"
70 .Fa "long close_flag"
71 .Fc
72 .Ft long
73 .Fo BIO_get_fd
74 .Fa "BIO *b"
75 .Fa "int *c"
76 .Fc
77 .Ft BIO *
78 .Fo BIO_new_fd
79 .Fa "int fd"
80 .Fa "int close_flag"
81 .Fc
82 .Sh DESCRIPTION
83 .Fn BIO_s_fd
84 returns the file descriptor BIO method.
85 This is a wrapper around the platform's file descriptor routines such as
86 .Xr read 2
87 and
88 .Xr write 2 .
89 .Pp
90 .Xr BIO_read 3
91 and
92 .Xr BIO_write 3
93 read or write the underlying descriptor.
94 .Xr BIO_puts 3
95 is supported but
96 .Xr BIO_gets 3
97 is not.
98 .Pp
99 If the close flag is set,
100 .Xr close 2
101 is called on the underlying file descriptor when the
102 .Vt BIO
103 is freed.
104 .Pp
105 .Xr BIO_reset 3
106 attempts to set the file pointer to the start of the file using
107 .Fn lseek fd 0 0 .
108 .Pp
109 .Xr BIO_seek 3
110 sets the file pointer to position
111 .Fa ofs
112 from start of file using
113 .Fn lseek fd ofs 0 .
114 .Pp
115 .Xr BIO_tell 3
116 returns the current file position by calling
117 .Fn lseek fd 0 1 .
118 .Pp
119 .Fn BIO_set_fd
120 sets the file descriptor of
121 .Vt BIO
122 .Fa b
123 to
124 .Fa fd
125 and the close flag to
126 .Fa close_flag .
127 It is currently implemented as a macro.
128 .Pp
129 .Fn BIO_get_fd
130 places the file descriptor in
131 .Fa c
132 if it is not
133 .Dv NULL
134 and also returns the file descriptor.
135 It is currently implemented as a macro.
136 .Pp
137 .Fn BIO_new_fd
138 returns a file descriptor BIO using
139 .Fa fd
140 and
141 .Fa close_flag .
142 .Pp
143 The behaviour of
144 .Xr BIO_read 3
145 and
146 .Xr BIO_write 3
147 depends on the behavior of the platform's
148 .Xr read 2
149 and
150 .Xr write 2
151 calls on the descriptor.
152 If the underlying file descriptor is in a non-blocking mode,
153 then the BIO will behave in the manner described in the
154 .Xr BIO_read 3
155 and
156 .Xr BIO_should_retry 3
157 manual pages.
158 .Pp
159 File descriptor BIOs should not be used for socket I/O.
160 Use socket BIOs instead.
161 .Pp
162 .Fn BIO_set_fd
163 and
164 .Fn BIO_get_fd
165 are implemented as macros.
166 .Sh RETURN VALUES
167 .Fn BIO_s_fd
168 returns the file descriptor BIO method.
169 .Pp
170 .Fn BIO_set_fd
171 always returns 1.
172 .Pp
173 .Fn BIO_get_fd
174 returns the file descriptor or -1 if the
175 .Vt BIO
176 has not been initialized.
177 .Pp
178 .Fn BIO_new_fd
179 returns the newly allocated
180 .Vt BIO
181 or
182 .Dv NULL
183 if an error occurred.
184 .Sh EXAMPLES
185 This is a file descriptor BIO version of "Hello World":
186 .Bd -literal -offset indent
187 BIO *out;
188 out = BIO_new_fd(fileno(stdout), BIO_NOCLOSE);
189 BIO_printf(out, "Hello World\en");
190 BIO_free(out);
191 .Ed
192 .Sh SEE ALSO
193 .Xr BIO_new 3 ,
194 .Xr BIO_read 3 ,
195 .Xr BIO_s_socket 3 ,
196 .Xr BIO_seek 3
197 .Sh HISTORY
198 These functions appeared in SSLeay 0.8.1b or earlier
199 and have been available since
200 .Ox 2.4 .