.\" gd_encoding_support.3.  The gd_encoding_support man page.
.\"
.\" Copyright (C) 2014 D. V. Wiebe
.\"
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.\" This file is part of the GetData project.
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.TH gd_encoding_support 3 "5 May 2014" "Version 0.9.0" "GETDATA"
.SH NAME
gd_encoding_support \(em determine GetData library support for data encodings
.SH SYNOPSIS
.B #include <getdata.h>
.HP
.nh
.ad l
.BI "int gd_encoding_support(unsigned long " encoding );
.hy
.ad n
.SH DESCRIPTION
The
.BR gd_encoding_support ()
function reports whether the Dirfile encoding specified by
.I encoding
is supported by the GetData library.  The
.I encoding
argument should be one of the following symbols, indicating the encoding type:
.IP
.nh
.ad l
.BR GD_UNENCODED ", " GD_BZIP2_ENCODED ", " GD_GZIP_ENCODED ,
.BR GD_LZMA_ENCODED ", " GD_SIE_ENCODED ", " GD_SLIM_ENCODED ,
.BR GD_TEXT_ENCODED ", " GD_ZZIP_ENCODED ", " GD_ZZSLIM_ENCODED .
.ad n
.hy
.PP
See
.BR gd_cbopen (3)
and dirfile-encoding(5) for the meanings of these symbols and details on the
known encoding schemes.

.SH RETURN VALUE
The function
.BR gd_encoding_support ()
returns
.B GD_RDWR
if the GetData library can read from and write to the specified encoding,
.B GD_RDONLY
if the GetData library can only read from the specified encoding, or -1 if
neither reading nor writing is supported, or if
.I encoding
was not one of the symbols listed above.
.SH NOTES
GetData's encoding support framework is more finely grained than the three-way
system reported by this function.  It is possible for the library to have
partial support for reading or writing a particular encoding.  This function
will only report positive support if
.I all
functions of a given class (read-only or read-write) are supported.

Furthermore, encoding types can have multiple subtypes with different degrees of
support.  This function reports the support of the
.I most supported
subtype.  For example, the LZMA encoding framework can read both the .lzma
and .xz container formats, but only write .xz files.  If LZMA support is available, this function
will return
.B GD_RDWR
when passed
.BR GD_LZMA_ENCODED .

.SH SEE ALSO
dirfile-encoding(5),
.BR gd_cbopen (3),
.BR gd_encoding (3)