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.Dd $Mdocdate: May 10 2019 $
.Dt KASSERT 9
.Os
.Sh NAME
.Nm assert ,
.Nm KASSERT ,
.Nm KDASSERT ,
.Nm KASSERTMSG ,
.Nm KDASSERTMSG ,
.Nm CTASSERT
.Nd kernel assert library routines
.Sh SYNOPSIS
.In sys/systm.h
.Ft "void"
.Fn assert "CONDITION"
.Ft "void"
.Fn KASSERT "CONDITION"
.Ft "void"
.Fn KDASSERT "CONDITION"
.Ft "void"
.Fn KASSERTMSG "CONDITION" "fmt" "..."
.Ft "void"
.Fn KDASSERTMSG "CONDITION" "fmt" "..."
.Ft "void"
.Fn CTASSERT "CONDITION"
.Sh DESCRIPTION
The
kernel
library implements a set of useful functions and macros implementing
expression verification.
.Pp
These macros cause kernel
.Xr panic 9
if the given condition evaluates to false.
.Fn assert
tests are always compiled in.
.Fn KASSERT
and
.Fn KASSERTMSG
tests are only included if the kernel has
.Dv DIAGNOSTIC
enabled.
.Fn KDASSERT
and
.Fn KDASSERTMSG
tests are only included if the kernel has
.Dv DEBUG
enabled.
The
.Fn KASSERTMSG
and
.Fn KDASSERTMSG
macros append
to the
.Xr panic 9
format string the message specified by
.Fa format
and its subsequent arguments, similar to
.Xr printf 9
functions.
.Pp
.Fn CTASSERT
causes a compile time error if the given condition evaluates to
false.
Its main purpose is to verify assertions about type and struct sizes that
would otherwise make the code fail at run time.
.Fn CTASSERT
can be used in global scope or at the start of blocks, where variable
declarations are allowed.
.Sh SEE ALSO
.Xr assert 3 ,
.Xr panic 9
.Sh HISTORY
The
.Fn KASSERTMSG
and
.Fn KDASSERTMSG
macros are taken from
.Nx .