1=pod
2
3=head1 NAME
4
5BIO_s_file, BIO_new_file, BIO_new_fp, BIO_set_fp, BIO_get_fp,
6BIO_read_filename, BIO_write_filename, BIO_append_filename,
7BIO_rw_filename - FILE bio
8
9=head1 SYNOPSIS
10
11 #include <openssl/bio.h>
12
13 BIO_METHOD *	BIO_s_file(void);
14 BIO *BIO_new_file(const char *filename, const char *mode);
15 BIO *BIO_new_fp(FILE *stream, int flags);
16
17 BIO_set_fp(BIO *b,FILE *fp, int flags);
18 BIO_get_fp(BIO *b,FILE **fpp);
19
20 int BIO_read_filename(BIO *b, char *name)
21 int BIO_write_filename(BIO *b, char *name)
22 int BIO_append_filename(BIO *b, char *name)
23 int BIO_rw_filename(BIO *b, char *name)
24
25=head1 DESCRIPTION
26
27BIO_s_file() returns the BIO file method. As its name implies it
28is a wrapper round the stdio FILE structure and it is a
29source/sink BIO.
30
31Calls to BIO_read() and BIO_write() read and write data to the
32underlying stream. BIO_gets() and BIO_puts() are supported on file BIOs.
33
34BIO_flush() on a file BIO calls the fflush() function on the wrapped
35stream.
36
37BIO_reset() attempts to change the file pointer to the start of file
38using fseek(stream, 0, 0).
39
40BIO_seek() sets the file pointer to position B<ofs> from start of file
41using fseek(stream, ofs, 0).
42
43BIO_eof() calls feof().
44
45Setting the BIO_CLOSE flag calls fclose() on the stream when the BIO
46is freed.
47
48BIO_new_file() creates a new file BIO with mode B<mode> the meaning
49of B<mode> is the same as the stdio function fopen(). The BIO_CLOSE
50flag is set on the returned BIO.
51
52BIO_new_fp() creates a file BIO wrapping B<stream>. Flags can be:
53BIO_CLOSE, BIO_NOCLOSE (the close flag) BIO_FP_TEXT (sets the underlying
54stream to text mode, default is binary: this only has any effect under
55Win32).
56
57BIO_set_fp() set the fp of a file BIO to B<fp>. B<flags> has the same
58meaning as in BIO_new_fp(), it is a macro.
59
60BIO_get_fp() retrieves the fp of a file BIO, it is a macro.
61
62BIO_seek() is a macro that sets the position pointer to B<offset> bytes
63from the start of file.
64
65BIO_tell() returns the value of the position pointer.
66
67BIO_read_filename(), BIO_write_filename(), BIO_append_filename() and
68BIO_rw_filename() set the file BIO B<b> to use file B<name> for
69reading, writing, append or read write respectively.
70
71=head1 NOTES
72
73When wrapping stdout, stdin or stderr the underlying stream should not
74normally be closed so the BIO_NOCLOSE flag should be set.
75
76Because the file BIO calls the underlying stdio functions any quirks
77in stdio behaviour will be mirrored by the corresponding BIO.
78
79=head1 EXAMPLES
80
81File BIO "hello world":
82
83 BIO *bio_out;
84 bio_out = BIO_new_fp(stdout, BIO_NOCLOSE);
85 BIO_printf(bio_out, "Hello World\n");
86
87Alternative technique:
88
89 BIO *bio_out;
90 bio_out = BIO_new(BIO_s_file());
91 if(bio_out == NULL) /* Error ... */
92 if(!BIO_set_fp(bio_out, stdout, BIO_NOCLOSE)) /* Error ... */
93 BIO_printf(bio_out, "Hello World\n");
94
95Write to a file:
96
97 BIO *out;
98 out = BIO_new_file("filename.txt", "w");
99 if(!out) /* Error occurred */
100 BIO_printf(out, "Hello World\n");
101 BIO_free(out);
102
103Alternative technique:
104
105 BIO *out;
106 out = BIO_new(BIO_s_file());
107 if(out == NULL) /* Error ... */
108 if(!BIO_write_filename(out, "filename.txt")) /* Error ... */
109 BIO_printf(out, "Hello World\n");
110 BIO_free(out);
111
112=head1 RETURN VALUES
113
114BIO_s_file() returns the file BIO method.
115
116BIO_new_file() and BIO_new_fp() return a file BIO or NULL if an error
117occurred.
118
119BIO_set_fp() and BIO_get_fp() return 1 for success or 0 for failure
120(although the current implementation never return 0).
121
122BIO_seek() returns the same value as the underlying fseek() function:
1230 for success or -1 for failure.
124
125BIO_tell() returns the current file position.
126
127BIO_read_filename(), BIO_write_filename(),  BIO_append_filename() and
128BIO_rw_filename() return 1 for success or 0 for failure.
129
130=head1 BUGS
131
132BIO_reset() and BIO_seek() are implemented using fseek() on the underlying
133stream. The return value for fseek() is 0 for success or -1 if an error
134occurred this differs from other types of BIO which will typically return
1351 for success and a non positive value if an error occurred.
136
137=head1 SEE ALSO
138
139L<BIO_seek(3)|BIO_seek(3)>, L<BIO_tell(3)|BIO_tell(3)>,
140L<BIO_reset(3)|BIO_reset(3)>, L<BIO_flush(3)|BIO_flush(3)>,
141L<BIO_read(3)|BIO_read(3)>,
142L<BIO_write(3)|BIO_write(3)>, L<BIO_puts(3)|BIO_puts(3)>,
143L<BIO_gets(3)|BIO_gets(3)>, L<BIO_printf(3)|BIO_printf(3)>,
144L<BIO_set_close(3)|BIO_set_close(3)>, L<BIO_get_close(3)|BIO_get_close(3)>
145