librecrypt/librecrypt_get_encoding.3 at master · maandree/librecrypt · GitHub

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.TH LIBRECRYPT_GET_ENCODING 3 LIBRECRYPT
.SH NAME
librecrypt_get_encoding - Get encoding alphabet for the last algorithm in a chain

.SH SYNOPSIS
.nf
#include <librecrypt.h>

const void *\fBlibrecrypt_get_encoding\fP(const char *\fIsettings\fP, size_t \fIlen\fP, char *\fIpad_out\fP,
                                    int *\fIstrict_pad_out\fP, int \fIdecoding\fP, LIBRECRYPT_CONTEXT *\fIctx\fP);
.fi
.PP
Link with
.IR -lrecrypt .

.SH DESCRIPTION
The
.BR librecrypt_get_encoding ()
function returns the ASCII encoding used for
the last algorithm in the algorithm chain
specified by
.IR settings .
.PP
If
.I decoding
is zero, the returned pointer is suitable for
use as the
.I lut
parameter to
.BR librecrypt_encode (3)
and points to an encoding alphabet consisting
of 64 characters repeated 4 times.
.PP
If
.I decoding
is non-zero, the returned pointer is suitable
for use as the
.I lut
parameter to
.BR librecrypt_decode (3)
and points to a reverse lookup table mapping
any valid character (except the padding
character) to its value in the encoding
alphabet and any other character to
.BR 0xFFu .
.PP
The
.I ctx
parameter is used for providing library
configurations, see
.BR librecrypt_create_context (3)
for more information; used
.I NULL
for default configurations.
.PP
On successful completion,
.IR *pad_out
is set to the padding character, or to the
null byte if there is no padding.
.IR *strict_pad_out
is set to 1 if padding is mandatory,
0 otherwise.
.IR *strict_pad_out
is set arbitrarily to 0 or 1 if
.IR *pad_out
is set to the null byte.
.PP
.I pad_out
and
.I strict_pad_out
must not be
.IR NULL .

.SH RETURN VALUES
The
.BR librecrypt_get_encoding ()
function returns a pointer to the encoding
data, or
.IR NULL
on failure. On failure,
.IR errno
is set to describe the error.

.SH ERRORS
The
.BR librecrypt_get_encoding ()
function will fail if:
.TP
.B ENOSYS
The last algorithm in
.I settings
is not recognised or was disabled at compile-time.

.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.PP
.TS
allbox;
lb lb lb
l l l.
Interface	Attribute	Value
T{
.BR librecrypt_get_encoding ()
T}	Thread safety	MT-Safe
T{
.BR librecrypt_get_encoding ()
T}	Async-signal safety	AS-Safe
.TE
.sp

.SH HISTORY
The
.BR librecrypt_get_encoding ()
function was introduced in version 1.0 of
.BR librecrypt .

Since version 1.1 of the
.BR librecrypt_get_encoding ()
function, the
.I ctx
parameter (previously called
.IR reserved )
has the type
.B LIBRECRYPT_CONTEXT *
(previously
.BR "void *" ),
and setting it to
.RI non- NULL
no longer causes failure with
.I errno
set to
.IR EINVAL .

.SH SEE ALSO
.BR librecrypt (7),
.BR librecrypt_encode (3),
.BR librecrypt_decode (3)