BIO_s_file, BIO_new_file, BIO_new_fp, BIO_set_fp, BIO_get_fp, BIO_read_filename,
BIO_write_filename, BIO_append_filename, BIO_rw_filename - FILE bio
#include <openssl/bio.h>
const BIO_METHOD *BIO_s_file(void);
BIO *BIO_new_file(const char *filename, const char *mode);
BIO *BIO_new_fp(FILE *stream, int flags);
BIO_set_fp(BIO *b, FILE *fp, int flags);
BIO_get_fp(BIO *b, FILE **fpp);
int BIO_read_filename(BIO *b, char *name);
int BIO_write_filename(BIO *b, char *name);
int BIO_append_filename(BIO *b, char *name);
int BIO_rw_filename(BIO *b, char *name);
BIO_s_file() returns the BIO file method. As its name implies it is a
wrapper round the stdio FILE structure and it is a source/sink BIO.
Calls to
BIO_read_ex() and
BIO_write_ex() read and write data to
the underlying stream.
BIO_gets() and
BIO_puts() are supported
on file BIOs.
BIO_flush() on a file BIO calls the
fflush() function on the
wrapped stream.
BIO_reset() attempts to change the file pointer to the start of file
using fseek(stream, 0, 0).
BIO_seek() sets the file pointer to position
ofs from start of
file using fseek(stream, ofs, 0).
BIO_eof() calls
feof().
Setting the BIO_CLOSE flag calls
fclose() on the stream when the BIO is
freed.
BIO_new_file() creates a new file BIO with mode
mode the meaning
of
mode is the same as the stdio function
fopen(). The BIO_CLOSE
flag is set on the returned BIO.
BIO_new_fp() creates a file BIO wrapping
stream. Flags can be:
BIO_CLOSE, BIO_NOCLOSE (the close flag) BIO_FP_TEXT (sets the underlying
stream to text mode, default is binary: this only has any effect under Win32).
BIO_set_fp() sets the fp of a file BIO to
fp.
flags has the
same meaning as in
BIO_new_fp(), it is a macro.
BIO_get_fp() retrieves the fp of a file BIO, it is a macro.
BIO_seek() is a macro that sets the position pointer to
offset
bytes from the start of file.
BIO_tell() returns the value of the position pointer.
BIO_read_filename(),
BIO_write_filename(),
BIO_append_filename() and
BIO_rw_filename() set the file BIO
b to use file
name for reading, writing, append or read write
respectively.
When wrapping stdout, stdin or stderr the underlying stream should not normally
be closed so the BIO_NOCLOSE 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.
On Windows BIO_new_files reserves for the filename argument to be UTF-8 encoded.
In other words if you have to make it work in multi- lingual environment,
encode filenames in UTF-8.
BIO_s_file() returns the file BIO method.
BIO_new_file() and
BIO_new_fp() return a file BIO or NULL if an
error occurred.
BIO_set_fp() and
BIO_get_fp() return 1 for success or <=0 for
failure (although the current implementation never return 0).
BIO_seek() returns 0 for success or negative values for failure.
BIO_tell() returns the current file position or negative values for
failure.
BIO_read_filename(),
BIO_write_filename(),
BIO_append_filename() and
BIO_rw_filename() return 1 for success
or <=0 for failure.
File BIO "hello world":
BIO *bio_out;
bio_out = BIO_new_fp(stdout, BIO_NOCLOSE);
BIO_printf(bio_out, "Hello World\n");
Alternative technique:
BIO *bio_out;
bio_out = BIO_new(BIO_s_file());
if (bio_out == NULL)
/* Error */
if (BIO_set_fp(bio_out, stdout, BIO_NOCLOSE) <= 0)
/* Error */
BIO_printf(bio_out, "Hello World\n");
Write to a file:
BIO *out;
out = BIO_new_file("filename.txt", "w");
if (!out)
/* Error */
BIO_printf(out, "Hello World\n");
BIO_free(out);
Alternative technique:
BIO *out;
out = BIO_new(BIO_s_file());
if (out == NULL)
/* Error */
if (BIO_write_filename(out, "filename.txt") <= 0)
/* Error */
BIO_printf(out, "Hello World\n");
BIO_free(out);
BIO_reset() and
BIO_seek() are implemented using
fseek() on
the underlying stream. The return value for
fseek() 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.
BIO_seek(3),
BIO_tell(3),
BIO_reset(3),
BIO_flush(3),
BIO_read_ex(3),
BIO_write_ex(3),
BIO_puts(3),
BIO_gets(3),
BIO_printf(3),
BIO_set_close(3),
BIO_get_close(3)
Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy in the
file LICENSE in the source distribution or at
<
https://www.openssl.org/source/license.html>.