bugfix: disallow encoding of empty array

This might be valid for JPEG specification, but for now it's better
to disallow it so that it doesn't segfault

closes JuliaImages/Images.jl#1018

Project.toml

@@ -1,7 +1,7 @@
 name = "JpegTurbo"
 uuid = "b835a17e-a41a-41e7-81f0-2f016b05efe0"
 authors = ["Johnny Chen <[email protected]>"]
-version = "0.1.1"
+version = "0.1.2"
 
 [deps]
 CEnum = "fa961155-64e5-5f13-b03f-caf6b980ea82"

src/encode.jl

@@ -76,6 +76,10 @@ function _encode(
     Y_density::Union{Nothing,Int} = nothing,
     write_Adobe_marker::Union{Nothing,Bool} = nothing
 )
+    if prod(size(img)) == 0
+        throw(ArgumentError("empty image is not allowed"))
+    end
+
     cinfo = LibJpeg.jpeg_compress_struct()
     cinfo_ref = Ref(cinfo)
     jerr = Ref{LibJpeg.jpeg_error_mgr}()

test/tst_encode.jl

@@ -24,6 +24,8 @@ img_rgb = testimage("lighthouse")
     img_or = 1.5 .* img
     img_or[1] = Gray(NaN)
     @test jpeg_encode(img_or) == jpeg_encode(Float64.(img_or)) == jpeg_encode(clamp01nan!(img_or))
+
+    @test_throws ArgumentError("empty image is not allowed") jpeg_encode(Array{Float64,2}(undef, 0, 0))
 end
 
 # keyword checks