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Avoid integer overflow when constructing arrays #26

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merged 6 commits into from
Apr 23, 2024
Merged

Avoid integer overflow when constructing arrays #26

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36d8f51
Avoid integer overflow when constructing arrays
giordano Apr 23, 2024
6f37870
reimplement `checked_dims` instead of using Julia internals
nsajko Apr 23, 2024
a7de257
Test more constructors
giordano Apr 23, 2024
51badad
weird codecov fix
nsajko Apr 23, 2024
9ece245
One more constructor test
giordano Apr 23, 2024
d0bde93
weird codecov fix
nsajko Apr 23, 2024
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20 changes: 19 additions & 1 deletion src/FixedSizeArrays.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -14,7 +14,7 @@
const FixedSizeMatrix{T} = FixedSizeArray{T,2}

function FixedSizeArray{T,N}(::UndefInitializer, size::NTuple{N,Int}) where {T,N}
FixedSizeArray{T,N}(Memory{T}(undef, prod(size)), size)
FixedSizeArray{T,N}(Memory{T}(undef, checked_dims(size)), size)
end
function FixedSizeArray{T,N}(::UndefInitializer, size::Vararg{Int,N}) where {T,N}
FixedSizeArray{T,N}(undef, size)
Expand All @@ -38,6 +38,24 @@

Base.isassigned(a::FixedSizeArray, i::Int) = isassigned(a.mem, i)

# safe product of a tuple of integers, for calculating dimensions size

checked_dims_impl(a::Int, ::Tuple{}) = a
function checked_dims_impl(a::Int, t::Tuple{Int,Vararg{Int,N}}) where {N}
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b = first(t)
(m, o) = Base.Checked.mul_with_overflow(a, b)
o && throw(ArgumentError("array dimensions too great, can't represent length"))
r = Base.tail(t)::NTuple{N,Int}
checked_dims_impl(m, r)::Int
end

checked_dims(::Tuple{}) = 1

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This method doesn't seem to be actually used? Or are there constructors I'm missing that'd call it?

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This should call it, I'll add a test:

julia> using FixedSizeArrays

julia> FixedSizeArray{Int,0}(undef, ())
0-dimensional FixedSizeArray{Int64, 0}:
0

function checked_dims(t::Tuple{Int,Vararg{Int,N}}) where {N}
a = first(t)
r = Base.tail(t)::NTuple{N,Int}
checked_dims_impl(a, r)::Int
end

# broadcasting

function Base.BroadcastStyle(::Type{<:FixedSizeArray})
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26 changes: 26 additions & 0 deletions test/runtests.jl
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Expand Up @@ -2,11 +2,37 @@ using Test
using FixedSizeArrays
import Aqua

const checked_dims = FixedSizeArrays.checked_dims

function allocated(f::F, args::Vararg{Any,N}) where {F,N}
@allocated f(args...)
end

@testset "FixedSizeArrays" begin
@testset "Aqua.jl" begin
Aqua.test_all(FixedSizeArrays)
end

@testset "Constructors" begin
@test FixedSizeArray{Float64,0}(undef) isa FixedSizeArray{Float64,0}
@test_throws ArgumentError FixedSizeArray{Float64,1}(undef, typemin(Int))
@test_throws ArgumentError FixedSizeArray{Float64,2}(undef, typemax(Int), typemax(Int))
@test_throws ArgumentError FixedSizeArray{Float64,3}(undef, typemax(Int), typemax(Int), 2)
@test_throws ArgumentError FixedSizeArray{Float64,4}(undef, typemax(Int), typemax(Int), 2, 4)
end

@testset "safe computation of length from dimensions size" begin
for n ∈ 0:30
t = Tuple(1:n)
if 20 < n
@test_throws ArgumentError checked_dims(t)
else
@test factorial(n) == prod(t) == @inferred checked_dims(t)
@test iszero(allocated(checked_dims, t))
end
end
end

@testset "FixedSizeVector" begin
v = FixedSizeVector{Float64}(undef, 3)
@test length(v) == 3
Expand Down
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