.\" Written by Björn Esser <besser82 at fedoraproject.org> in 2018.
.\"
.\" To the extent possible under law, the authors have waived
.\" all copyright and related or neighboring rights to this work.
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.\" details.
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.Dd November 16, 2018
.Dt CRYPT_PREFERRED_METHOD 3
.Os "libxcrypt"
.Sh NAME
.Nm crypt_preferred_method
.Nd get the prefix of the preferred hash method
.Sh LIBRARY
.Lb libcrypt
.Sh SYNOPSIS
.In crypt.h
.Ft const char*
.Fo crypt_preferred_method
.Fa "void"
.Fc
.Sh DESCRIPTION
.Nm
is a convenience function to get the prefix of the preferred hash
method.  If a preferred method is available, it is the same as the
one also used by the
.Nm crypt_gensalt functions ,
if their given
.Ar prefix
parameter is NULL.
.Sh RETURN VALUES
The string returned equals the prefix of the preferred hash method.
If no preferred hash method is available it is NULL.  It
.Em is
safe to pass the string returned by
.Nm crypt_preferred_method
directly to
.Nm crypt_gensalt
without prior string-sanitizing nor NULL-pointer checks.
.Sh FEATURE TEST MACROS
.In crypt.h
will define the macro
.Dv CRYPT_PREFERRED_METHOD_AVAILABLE
if
.Nm
is available in the current version of libxcrypt.
.Sh PORTABILITY NOTES
The function
.Nm
is not part of any standard.
It was added to libxcrypt in version 4.4.0.
.Sh ATTRIBUTES
For an explanation of the terms used in this section, see
.Xr attributes 7 .
.TS
allbox;
lb lb lb
l l l.
Interface	Attribute	Value
T{
.Nm
T}	Thread safety	MT-Safe
.TE
.sp
.Sh SEE ALSO
.Xr crypt_gensalt 3