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 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); 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_ex() and BIO_write_ex() 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() sets 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 RETURN VALUES 84 85BIO_s_file() returns the file BIO method. 86 87BIO_new_file() and BIO_new_fp() return a file BIO or NULL if an error 88occurred. 89 90BIO_set_fp() and BIO_get_fp() return 1 for success or 0 for failure 91(although the current implementation never return 0). 92 93BIO_seek() returns the same value as the underlying fseek() function: 940 for success or -1 for failure. 95 96BIO_tell() returns the current file position. 97 98BIO_read_filename(), BIO_write_filename(), BIO_append_filename() and 99BIO_rw_filename() return 1 for success or 0 for failure. 100 101=head1 EXAMPLES 102 103File BIO "hello world": 104 105 BIO *bio_out; 106 107 bio_out = BIO_new_fp(stdout, BIO_NOCLOSE); 108 BIO_printf(bio_out, "Hello World\n"); 109 110Alternative technique: 111 112 BIO *bio_out; 113 114 bio_out = BIO_new(BIO_s_file()); 115 if (bio_out == NULL) 116 /* Error */ 117 if (!BIO_set_fp(bio_out, stdout, BIO_NOCLOSE)) 118 /* Error */ 119 BIO_printf(bio_out, "Hello World\n"); 120 121Write to a file: 122 123 BIO *out; 124 125 out = BIO_new_file("filename.txt", "w"); 126 if (!out) 127 /* Error */ 128 BIO_printf(out, "Hello World\n"); 129 BIO_free(out); 130 131Alternative technique: 132 133 BIO *out; 134 135 out = BIO_new(BIO_s_file()); 136 if (out == NULL) 137 /* Error */ 138 if (!BIO_write_filename(out, "filename.txt")) 139 /* Error */ 140 BIO_printf(out, "Hello World\n"); 141 BIO_free(out); 142 143=head1 BUGS 144 145BIO_reset() and BIO_seek() are implemented using fseek() on the underlying 146stream. The return value for fseek() is 0 for success or -1 if an error 147occurred this differs from other types of BIO which will typically return 1481 for success and a non positive value if an error occurred. 149 150=head1 SEE ALSO 151 152L<BIO_seek(3)>, L<BIO_tell(3)>, 153L<BIO_reset(3)>, L<BIO_flush(3)>, 154L<BIO_read_ex(3)>, 155L<BIO_write_ex(3)>, L<BIO_puts(3)>, 156L<BIO_gets(3)>, L<BIO_printf(3)>, 157L<BIO_set_close(3)>, L<BIO_get_close(3)> 158 159=head1 COPYRIGHT 160 161Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved. 162 163Licensed under the OpenSSL license (the "License"). You may not use 164this file except in compliance with the License. You can obtain a copy 165in the file LICENSE in the source distribution or at 166L<https://www.openssl.org/source/license.html>. 167 168=cut 169