.\" $OpenBSD: BIO_s_file.3,v 1.5 2016/12/06 14:45:08 schwarze Exp $ .\" OpenSSL 9b86974e Aug 17 15:21:33 2015 -0400 .\" .\" This file was written by Dr. Stephen Henson . .\" Copyright (c) 2000, 2010 The OpenSSL Project. All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in .\" the documentation and/or other materials provided with the .\" distribution. .\" .\" 3. All advertising materials mentioning features or use of this .\" software must display the following acknowledgment: .\" "This product includes software developed by the OpenSSL Project .\" for use in the OpenSSL Toolkit. (http://www.openssl.org/)" .\" .\" 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to .\" endorse or promote products derived from this software without .\" prior written permission. For written permission, please contact .\" openssl-core@openssl.org. .\" .\" 5. Products derived from this software may not be called "OpenSSL" .\" nor may "OpenSSL" appear in their names without prior written .\" permission of the OpenSSL Project. .\" .\" 6. Redistributions of any form whatsoever must retain the following .\" acknowledgment: .\" "This product includes software developed by the OpenSSL Project .\" for use in the OpenSSL Toolkit (http://www.openssl.org/)" .\" .\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY .\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR .\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR .\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, .\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; .\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, .\" STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED .\" OF THE POSSIBILITY OF SUCH DAMAGE. .\" .Dd $Mdocdate: December 6 2016 $ .Dt BIO_S_FILE 3 .Os .Sh NAME .Nm BIO_s_file , .Nm BIO_new_file , .Nm BIO_new_fp , .Nm BIO_set_fp , .Nm BIO_get_fp , .Nm BIO_read_filename , .Nm BIO_write_filename , .Nm BIO_append_filename , .Nm BIO_rw_filename .Nd FILE BIO .Sh SYNOPSIS .In openssl/bio.h .Ft BIO_METHOD * .Fo BIO_s_file .Fa void .Fc .Ft BIO * .Fo BIO_new_file .Fa "const char *filename" .Fa "const char *mode" .Fc .Ft BIO * .Fo BIO_new_fp .Fa "FILE *stream" .Fa "int flags" .Fc .Ft long .Fo BIO_set_fp .Fa "BIO *b" .Fa "FILE *fp" .Fa "int flags" .Fc .Ft long .Fo BIO_get_fp .Fa "BIO *b" .Fa "FILE **fpp" .Fc .Ft int .Fo BIO_read_filename .Fa "BIO *b" .Fa "char *name" .Fc .Ft int .Fo BIO_write_filename .Fa "BIO *b" .Fa "char *name" .Fc .Ft int .Fo BIO_append_filename .Fa "BIO *b" .Fa "char *name" .Fc .Ft int .Fo BIO_rw_filename .Fa "BIO *b" .Fa "char *name" .Fc .Sh DESCRIPTION .Fn BIO_s_file returns the BIO file method. As its name implies, it is a wrapper around the stdio .Vt FILE structure and it is a source/sink BIO. .Pp Calls to .Xr BIO_read 3 and .Xr BIO_write 3 read and write data to the underlying stream. .Xr BIO_gets 3 and .Xr BIO_puts 3 are supported on file BIOs. .Pp .Xr BIO_flush 3 on a file BIO calls the .Xr fflush 3 function on the wrapped stream. .Pp .Xr BIO_reset 3 attempts to change the file pointer to the start of file using .Fn fseek stream 0 0 . .Pp .Xr BIO_seek 3 sets the file pointer to position .Fa ofs from the start of the file using .Fn fseek stream ofs 0 . .Pp .Xr BIO_eof 3 calls .Xr feof 3 . .Pp Setting the .Dv BIO_CLOSE flag calls .Xr fclose 3 on the stream when the BIO is freed. .Pp .Fn BIO_new_file creates a new file BIO with mode .Fa mode . The meaning of .Fa mode is the same as for the stdio function .Xr fopen 3 . The .Dv BIO_CLOSE flag is set on the returned BIO. .Pp .Fn BIO_new_fp creates a file BIO wrapping .Fa stream . Flags can be: .Dv BIO_CLOSE , BIO_NOCLOSE Pq the close flag , .Dv BIO_FP_TEXT (sets the underlying stream to text mode, default is binary: this only has any effect under Win32). .Pp .Fn BIO_set_fp set the file pointer of a file BIO to .Fa fp . .Fa flags has the same meaning as in .Fn BIO_new_fp . .Fn BIO_set_fp is a macro. .Pp .Fn BIO_get_fp retrieves the file pointer of a file BIO, it is a macro. .Pp .Xr BIO_seek 3 is a macro that sets the position pointer to .Fa offset bytes from the start of file. .Pp .Xr BIO_tell 3 returns the value of the position pointer. .Pp .Fn BIO_read_filename , .Fn BIO_write_filename , .Fn BIO_append_filename , and .Fn BIO_rw_filename set the file BIO .Fa b to use file .Fa name for reading, writing, append or read write respectively. .Pp When wrapping stdout, stdin, or stderr, the underlying stream should not normally be closed, so the .Dv BIO_NOCLOSE flag should be set. .Pp Because the file BIO calls the underlying stdio functions, any quirks in stdio behaviour will be mirrored by the corresponding BIO. .Pp On Windows, .Fn BIO_new_files 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 in UTF-8. .Sh RETURN VALUES .Fn BIO_s_file returns the file BIO method. .Pp .Fn BIO_new_file and .Fn BIO_new_fp return a file BIO or .Dv NULL if an error occurred. .Pp .Fn BIO_set_fp and .Fn BIO_get_fp return 1 for success or 0 for failure (although the current implementation never returns 0). .Pp .Xr BIO_seek 3 returns the same value as the underlying .Xr fseek 3 function: 0 for success or -1 for failure. .Pp .Xr BIO_tell 3 returns the current file position. .Pp .Fn BIO_read_filename , .Fn BIO_write_filename , .Fn BIO_append_filename , and .Fn BIO_rw_filename return 1 for success or 0 for failure. .Sh EXAMPLES File BIO "hello world": .Bd -literal -offset indent BIO *bio_out; bio_out = BIO_new_fp(stdout, BIO_NOCLOSE); BIO_printf(bio_out, "Hello World\en"); .Ed .Pp Alternative technique: .Bd -literal -offset indent 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\en"); .Ed .Pp Write to a file: .Bd -literal -offset indent BIO *out; out = BIO_new_file("filename.txt", "w"); if(!out) /* Error occurred */ BIO_printf(out, "Hello World\en"); BIO_free(out); .Ed .Pp Alternative technique: .Bd -literal -offset indent 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\en"); BIO_free(out); .Ed .Sh SEE ALSO .Xr BIO_new 3 , .Xr BIO_read 3 , .Xr BIO_seek 3 .Sh BUGS .Xr BIO_reset 3 and .Xr BIO_seek 3 are implemented using .Xr fseek 3 on the underlying stream. The return value for .Xr 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.