BIO_s_file(3)               OpenSSL               BIO_s_file(3)





NAME
       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

SYNOPSIS
        #include <openssl/bio.h>

        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)

DESCRIPTION
       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() and BIO_write() 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() set 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.

NOTES
       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 func-
       tions any quirks in stdio behaviour will be mirrored by
       the corresponding BIO.

EXAMPLES
       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)) /* 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);

       Alternative technique:

        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);

RETURN VALUES
       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 the same value as the underlying
       fseek() function: 0 for success or -1 for failure.

       BIO_tell() returns the current file position.

       BIO_read_filename(), BIO_write_filename(),
       BIO_append_filename() and BIO_rw_filename() return 1 for
       success or 0 for failure.

BUGS
       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.

SEE ALSO
       BIO_seek(3), BIO_tell(3), BIO_reset(3), BIO_flush(3),
       BIO_read(3), BIO_write(3), BIO_puts(3), BIO_gets(3),
       BIO_printf(3), BIO_set_close(3), BIO_get_close(3)



0.9.7c                     2000-09-19             BIO_s_file(3)
