BIO_s_file(3ssl)

1BIO_S_FILE(3)                       OpenSSL                      BIO_S_FILE(3)
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NAME

6       BIO_s_file, BIO_new_file, BIO_new_fp, BIO_set_fp, BIO_get_fp,
7       BIO_read_filename, BIO_write_filename, BIO_append_filename,
8       BIO_rw_filename - FILE bio
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SYNOPSIS

11        #include <openssl/bio.h>
12
13        const 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);
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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)
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DESCRIPTION

26       BIO_s_file() returns the BIO file method. As its name implies it is a
27       wrapper round the stdio FILE structure and it is a source/sink BIO.
28
29       Calls to BIO_read_ex() and BIO_write_ex() read and write data to the
30       underlying stream. BIO_gets() and BIO_puts() are supported on file
31       BIOs.
32
33       BIO_flush() on a file BIO calls the fflush() function on the wrapped
34       stream.
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36       BIO_reset() attempts to change the file pointer to the start of file
37       using fseek(stream, 0, 0).
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39       BIO_seek() sets the file pointer to position ofs from start of file
40       using fseek(stream, ofs, 0).
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42       BIO_eof() calls feof().
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44       Setting the BIO_CLOSE flag calls fclose() on the stream when the BIO is
45       freed.
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47       BIO_new_file() creates a new file BIO with mode mode the meaning of
48       mode is the same as the stdio function fopen(). The BIO_CLOSE flag is
49       set on the returned BIO.
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51       BIO_new_fp() creates a file BIO wrapping stream. Flags can be:
52       BIO_CLOSE, BIO_NOCLOSE (the close flag) BIO_FP_TEXT (sets the
53       underlying stream to text mode, default is binary: this only has any
54       effect under Win32).
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56       BIO_set_fp() sets the fp of a file BIO to fp. flags has the same
57       meaning as in BIO_new_fp(), it is a macro.
58
59       BIO_get_fp() retrieves the fp of a file BIO, it is a macro.
60
61       BIO_seek() is a macro that sets the position pointer to offset bytes
62       from the start of file.
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64       BIO_tell() returns the value of the position pointer.
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66       BIO_read_filename(), BIO_write_filename(), BIO_append_filename() and
67       BIO_rw_filename() set the file BIO b to use file name for reading,
68       writing, append or read write respectively.
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NOTES

71       When wrapping stdout, stdin or stderr the underlying stream should not
72       normally be closed so the BIO_NOCLOSE flag should be set.
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74       Because the file BIO calls the underlying stdio functions any quirks in
75       stdio behaviour will be mirrored by the corresponding BIO.
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77       On Windows BIO_new_files reserves for the filename argument to be UTF-8
78       encoded. In other words if you have to make it work in multi- lingual
79       environment, encode file names in UTF-8.
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EXAMPLES

82       File BIO "hello world":
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84        BIO *bio_out;
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86        bio_out = BIO_new_fp(stdout, BIO_NOCLOSE);
87        BIO_printf(bio_out, "Hello World\n");
88
89       Alternative technique:
90
91        BIO *bio_out;
92
93        bio_out = BIO_new(BIO_s_file());
94        if (bio_out == NULL)
95            /* Error */
96        if (!BIO_set_fp(bio_out, stdout, BIO_NOCLOSE))
97            /* Error */
98        BIO_printf(bio_out, "Hello World\n");
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100       Write to a file:
101
102        BIO *out;
103
104        out = BIO_new_file("filename.txt", "w");
105        if (!out)
106            /* Error */
107        BIO_printf(out, "Hello World\n");
108        BIO_free(out);
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110       Alternative technique:
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112        BIO *out;
113
114        out = BIO_new(BIO_s_file());
115        if (out == NULL)
116            /* Error */
117        if (!BIO_write_filename(out, "filename.txt"))
118            /* Error */
119        BIO_printf(out, "Hello World\n");
120        BIO_free(out);
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RETURN VALUES

123       BIO_s_file() returns the file BIO method.
124
125       BIO_new_file() and BIO_new_fp() return a file BIO or NULL if an error
126       occurred.
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128       BIO_set_fp() and BIO_get_fp() return 1 for success or 0 for failure
129       (although the current implementation never return 0).
130
131       BIO_seek() returns the same value as the underlying fseek() function: 0
132       for success or -1 for failure.
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134       BIO_tell() returns the current file position.
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136       BIO_read_filename(), BIO_write_filename(), BIO_append_filename() and
137       BIO_rw_filename() return 1 for success or 0 for failure.
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BUGS

140       BIO_reset() and BIO_seek() are implemented using fseek() on the
141       underlying stream. The return value for fseek() is 0 for success or -1
142       if an error occurred this differs from other types of BIO which will
143       typically return 1 for success and a non positive value if an error
144       occurred.
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COPYRIGHT

152       Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
153
154       Licensed under the OpenSSL license (the "License").  You may not use
155       this file except in compliance with the License.  You can obtain a copy
156       in the file LICENSE in the source distribution or at
157       <https://www.openssl.org/source/license.html>.
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1611.1.1                             2018-09-11                     BIO_S_FILE(3)