Allow unread of AbstractVector{UInt8} (#212)

Author: nhz2

src/buffer.jl

@@ -127,7 +127,7 @@ end
 
 # Make margin with ≥`minsize` and return the size of it.
 # If eager is true, it tries to move data even when the buffer has enough margin.
-function makemargin!(buf::Buffer, minsize::Integer; eager::Bool = false)
+function makemargin!(buf::Buffer, minsize::Int; eager::Bool = false)
     @assert minsize ≥ 0
     if buffersize(buf) == 0 && buf.markpos == 0
         buf.bufferpos = buf.marginpos = 1
@@ -156,7 +156,7 @@ function makemargin!(buf::Buffer, minsize::Integer; eager::Bool = false)
     # At least enough for minsize, but otherwise 1.5 times
     if marginsize(buf) < minsize
         datasize = length(buf.data)
-        resize!(buf.data, max(buf.marginpos + minsize - 1, datasize + div(datasize, 2)))
+        resize!(buf.data, max(Base.checked_add(buf.marginpos, minsize) - 1, datasize + div(datasize, 2)))
     end
     @assert marginsize(buf) ≥ minsize
     return marginsize(buf)
@@ -185,7 +185,7 @@ end
 
 # Copy data from `data` to `buf`.
 function copydata!(buf::Buffer, data::Ptr{UInt8}, nbytes::Integer)
-    makemargin!(buf, nbytes)
+    makemargin!(buf, Int(nbytes))
     GC.@preserve buf unsafe_copyto!(marginptr(buf), data, nbytes)
     supplied!(buf, nbytes)
     return buf
@@ -202,7 +202,9 @@ function copydata!(data::Ptr{UInt8}, buf::Buffer, nbytes::Integer)
 end
 
 # Insert data to the current buffer.
-function insertdata!(buf::Buffer, data::Ptr{UInt8}, nbytes::Integer)
+# `data` must not alias `buf`
+function insertdata!(buf::Buffer, data::Union{AbstractArray{UInt8}, Memory})
+    nbytes = Int(length(data))
     makemargin!(buf, nbytes)
     datapos = if iszero(buf.markpos)
         # If data is not marked we must not discard buffered (nonconsumed) data
@@ -213,7 +215,9 @@ function insertdata!(buf::Buffer, data::Ptr{UInt8}, nbytes::Integer)
     end
     datasize = buf.marginpos - datapos
     copyto!(buf.data, datapos + nbytes, buf.data, datapos, datasize)
-    GC.@preserve buf unsafe_copyto!(bufferptr(buf), data, nbytes)
+    for i in 0:nbytes-1
+        buf.data[buf.bufferpos + i] = data[firstindex(data) + i]
+    end
     supplied!(buf, nbytes)
     if !iszero(buf.markpos)
         buf.markpos += nbytes

src/memory.jl

@@ -19,6 +19,10 @@ end
     return mem.size
 end
 
+@inline function Base.firstindex(mem::Memory)
+    return 1
+end
+
 @inline function Base.lastindex(mem::Memory)
     return Int(mem.size)
 end

src/noop.jl

@@ -120,7 +120,7 @@ function Base.unsafe_write(stream::NoopStream, input::Ptr{UInt8}, nbytes::UInt):
     end
     buffer = stream.buffer1
     if marginsize(buffer) ≥ nbytes
-        copydata!(buffer, input, nbytes)
+        copydata!(buffer, input, Int(nbytes))
         return Int(nbytes)
     else
         flushbuffer(stream)

src/stream.jl

@@ -442,15 +442,18 @@ function Base.readavailable(stream::TranscodingStream)
 end
 
 """
-    unread(stream::TranscodingStream, data::Vector{UInt8})
+    unread(stream::TranscodingStream, data::AbstractVector{UInt8})
 
 Insert `data` to the current reading position of `stream`.
 
 The next `read(stream, sizeof(data))` call will read data that are just
 inserted.
+
+`data` must not alias any internal buffers in `stream`
 """
-function unread(stream::TranscodingStream, data::ByteData)
-    GC.@preserve data unsafe_unread(stream, pointer(data), sizeof(data))
+function unread(stream::TranscodingStream, data::AbstractVector{UInt8})
+    insertdata!(stream.buffer1, data)
+    return nothing
 end
 
 """
@@ -460,13 +463,15 @@ Insert `nbytes` pointed by `data` to the current reading position of `stream`.
 
 The data are copied into the internal buffer and hence `data` can be safely used
 after the operation without interfering the stream.
+
+`data` must not alias any internal buffers in `stream`
 """
 function unsafe_unread(stream::TranscodingStream, data::Ptr, nbytes::Integer)
     if nbytes < 0
         throw(ArgumentError("negative nbytes"))
     end
     ready_to_read!(stream)
-    insertdata!(stream.buffer1, convert(Ptr{UInt8}, data), nbytes)
+    insertdata!(stream.buffer1, Memory(convert(Ptr{UInt8}, data), UInt(nbytes)))
     return nothing
 end
 
@@ -702,7 +707,7 @@ function callprocess(stream::TranscodingStream, inbuf::Buffer, outbuf::Buffer)
         if stream.state.mode == :read
             if stream.stream isa TranscodingStream && !has_sharedbuf(stream) && !iszero(buffersize(inbuf))
                 # unread data to match behavior if inbuf was shared.
-                GC.@preserve inbuf unsafe_unread(stream.stream, bufferptr(inbuf), buffersize(inbuf))
+                unread(stream.stream, view(inbuf.data, inbuf.bufferpos:inbuf.marginpos-1))
             end
             changemode!(stream, :stop)
         end

test/Project.toml

@@ -1,5 +1,7 @@
 [deps]
 Aqua = "4c88cf16-eb10-579e-8560-4a9242c79595"
+FillArrays = "1a297f60-69ca-5386-bcde-b61e274b549b"
+OffsetArrays = "6fe1bfb0-de20-5000-8ca7-80f57d26f881"
 Random = "9a3f8284-a2c9-5f02-9a11-845980a1fd5c"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
 TranscodingStreams = "3bb67fe8-82b1-5028-8e26-92a6c54297fa"

test/codecnoop.jl

@@ -1,3 +1,6 @@
+using OffsetArrays: OffsetArray
+using FillArrays: Zeros
+
 @testset "Noop Codec" begin
     source = IOBuffer("")
     stream = TranscodingStream(Noop(), source)
@@ -339,6 +342,32 @@
         stream = NoopStream(IOBuffer("foobar"))
         @test_throws ArgumentError TranscodingStreams.unsafe_unread(stream, pointer(b"foo"), -1)
         close(stream)
+
+        stream = NoopStream(IOBuffer("foo"))
+        @test read(stream, 3) == b"foo"
+        @test TranscodingStreams.unread(stream, OffsetArray(b"bar", -5:-3)) === nothing
+        @test read(stream, 3) == b"bar"
+        close(stream)
+
+        stream = NoopStream(IOBuffer("foobar"))
+        @test read(stream, 3) == b"foo"
+        @test_throws OverflowError TranscodingStreams.unread(stream, Zeros{UInt8}(typemax(Int))) === nothing
+        close(stream)
+
+        stream = NoopStream(IOBuffer("foo"))
+        @test read(stream, 3) == b"foo"
+        @test TranscodingStreams.unread(stream, Zeros{UInt8}(big(3))) === nothing
+        @test read(stream, 3) == b"\0\0\0"
+        close(stream)
+
+        stream = NoopStream(IOBuffer("foo"))
+        @test read(stream, 3) == b"foo"
+        d = b"bar"
+        GC.@preserve d begin
+            @test TranscodingStreams.unsafe_unread(stream, pointer(d), 3) === nothing
+        end
+        @test read(stream, 3) == b"bar"
+        close(stream)
     end
 
     stream = NoopStream(IOBuffer(""))