const BIO_METHOD *
*filename, const char *mode);
FILE *fp, int flags);
returns the BIO file method. As its name implies, it is a wrapper around the
stdio FILE structure and it is a source/sink BIO.
Calls to BIO_read(3) and BIO_write(3) read and write data to the underlying stream. BIO_gets(3) and BIO_puts(3) are supported on file BIOs.
BIO_flush(3) on a file BIO calls the fflush(3) function on the wrapped stream.
BIO_reset(3) attempts to change the file pointer to the start
of file using
BIO_seek(3) sets the file pointer to position
ofs from the start of the file using
BIO_eof(3) calls feof(3).
BIO_CLOSE flag calls
on the stream when the BIO is freed.
creates a new file BIO with mode mode. The meaning of
mode is the same as for the stdio function
BIO_CLOSE flag is set on the returned BIO.
creates a file BIO wrapping stream. Flags can be:
BIO_FP_TEXT (sets the underlying stream
to text mode, default is binary: this only has any effect under Win32).
sets the file pointer of a file BIO to fp.
flags has the same meaning as in
is a macro.
retrieves the file pointer of a file BIO, it is a macro.
BIO_seek(3) is a macro that sets the position pointer to offset bytes from the start of file.
BIO_tell(3) returns the value of the position pointer.
set the file BIO b to use file
name for reading, writing, append or read write
When wrapping stdout, stdin, or stderr, the underlying stream
should not normally be closed, so the
flag should be set.
Because the file BIO calls the underlying stdio functions, any quirks in stdio behaviour will be mirrored by the corresponding BIO.
reserves for the filename argument to be UTF-8 encoded. In other words, if
you have to make it work in a multi-lingual environment, encode file names
BIO_s_file() returns the file BIO
BIO_new_fp() return a file BIO or
NULL if an error occurred.
BIO_get_fp() return 1 for success or 0 for failure
(although the current implementation never returns 0).
BIO_seek(3) returns the same value as the underlying fseek(3) function: 0 for success or -1 for failure.
BIO_tell(3) returns the current file position.
BIO_rw_filename() return 1 for success or 0 for
File BIO "hello world":
BIO *bio_out; bio_out = BIO_new_fp(stdout, BIO_NOCLOSE); BIO_printf(bio_out, "Hello World\n");
BIO *bio_out; bio_out = BIO_new(BIO_s_file()); if(bio_out == NULL) /* Error ... */ if(!BIO_set_fp(bio_out, stdout, BIO_NOCLOSE)) /* Error ... */ BIO_printf(bio_out, "Hello World\n");
Write to a file:
BIO *out; out = BIO_new_file("filename.txt", "w"); if(!out) /* Error occurred */ BIO_printf(out, "Hello World\n"); BIO_free(out);
BIO *out; out = BIO_new(BIO_s_file()); if(out == NULL) /* Error ... */ if(!BIO_write_filename(out, "filename.txt")) /* Error ... */ BIO_printf(out, "Hello World\n"); BIO_free(out);
BIO_new(3), BIO_read(3), BIO_seek(3)
BIO_append_filename() first appeared in SSLeay
BIO_new_fp() first appeared in SSLeay 0.8.0. All
these functions have been available since OpenBSD
BIO_rw_filename() first appeared in SSLeay
0.9.1 and has been available since OpenBSD 2.6.
BIO_reset(3) and BIO_seek(3) are implemented using fseek(3) on the underlying stream. The return value for fseek(3) is 0 for success or -1 if an error occurred. This differs from other types of BIO which will typically return 1 for success and a non-positive value if an error occurred.