.Dd January 15, 2017
.Dt DEFLATEBOUND 3
.Os
.
.Sh NAME
.Nm deflateBound
.Nd compressed size upper bound
.
.Sh LIBRARY
.Lb libz
.
.Sh SYNOPSIS
.In zlib.h
.Ft uLong
.Fn deflateBound "z_streamp strm" "uLong sourceLen"
.
.Sh DESCRIPTION
.Fn deflateBound
returns an upper bound
on the compressed size
after deflation of
.Fa sourceLen
bytes.
It must be called after
.Xr deflateInit 3
or
.Xr deflateInit2 3 ,
and after
.Xr deflateSetHeader 3 ,
if used.
This would be used
to allocate an output buffer
for deflation in a single pass,
and so would be called before
.Xr deflate 3 .
If that first
.Fn deflate
call is provided the
.Fa sourceLen
input bytes,
an output buffer allocated
to the size returned by
.Fn deflateBound ,
and the flush value
.Dv Z_FINISH ,
then
.Fn deflate
is guaranteed to return
.Dv Z_STREAM_END .
Note that it is possible
for the compressed size
to be larger than the value returned by
.Fn deflateBound
if flush options other than
.Dv Z_FINISH
or
.Dv Z_NO_FLUSH
are used.
.
.Sh SEE ALSO
.Xr compressBound 3
.
.Sh HISTORY
This manual page was converted from
.In zlib.h
to mdoc format by
.An C. McEnroe Aq Mt june@causal.agency .
.
.Sh AUTHORS
.An Jean-loup Gailly Aq Mt jloup@gzip.org
.An Mark Adler Aq Mt madler@alumni.caltech.edu