BIO_s_file.pod revision 302408
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