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
79On Windows BIO_new_files reserves for the filename argument to be
80UTF-8 encoded. In other words if you have to make it work in multi-
81lingual environment, encode file names in UTF-8.
82
83=head1 EXAMPLES
84
85File BIO "hello world":
86
87 BIO *bio_out;
88 bio_out = BIO_new_fp(stdout, BIO_NOCLOSE);
89 BIO_printf(bio_out, "Hello World\n");
90
91Alternative technique:
92
93 BIO *bio_out;
94 bio_out = BIO_new(BIO_s_file());
95 if(bio_out == NULL) /* Error ... */
96 if(!BIO_set_fp(bio_out, stdout, BIO_NOCLOSE)) /* Error ... */
97 BIO_printf(bio_out, "Hello World\n");
98
99Write to a file:
100
101 BIO *out;
102 out = BIO_new_file("filename.txt", "w");
103 if(!out) /* Error occurred */
104 BIO_printf(out, "Hello World\n");
105 BIO_free(out);
106
107Alternative technique:
108
109 BIO *out;
110 out = BIO_new(BIO_s_file());
111 if(out == NULL) /* Error ... */
112 if(!BIO_write_filename(out, "filename.txt")) /* Error ... */
113 BIO_printf(out, "Hello World\n");
114 BIO_free(out);
115
116=head1 RETURN VALUES
117
118BIO_s_file() returns the file BIO method.
119
120BIO_new_file() and BIO_new_fp() return a file BIO or NULL if an error
121occurred.
122
123BIO_set_fp() and BIO_get_fp() return 1 for success or 0 for failure
124(although the current implementation never return 0).
125
126BIO_seek() returns the same value as the underlying fseek() function:
1270 for success or -1 for failure.
128
129BIO_tell() returns the current file position.
130
131BIO_read_filename(), BIO_write_filename(),  BIO_append_filename() and
132BIO_rw_filename() return 1 for success or 0 for failure.
133
134=head1 BUGS
135
136BIO_reset() and BIO_seek() are implemented using fseek() on the underlying
137stream. The return value for fseek() is 0 for success or -1 if an error
138occurred this differs from other types of BIO which will typically return
1391 for success and a non positive value if an error occurred.
140
141=head1 SEE ALSO
142
143L<BIO_seek(3)|BIO_seek(3)>, L<BIO_tell(3)|BIO_tell(3)>,
144L<BIO_reset(3)|BIO_reset(3)>, L<BIO_flush(3)|BIO_flush(3)>,
145L<BIO_read(3)|BIO_read(3)>,
146L<BIO_write(3)|BIO_write(3)>, L<BIO_puts(3)|BIO_puts(3)>,
147L<BIO_gets(3)|BIO_gets(3)>, L<BIO_printf(3)|BIO_printf(3)>,
148L<BIO_set_close(3)|BIO_set_close(3)>, L<BIO_get_close(3)|BIO_get_close(3)>
149