new Base64 encoder and decoder

doc/make.jl

@@ -25,11 +25,13 @@ if Sys.iswindows()
     cp_q("../stdlib/Test/docs/src/index.md", "src/stdlib/test.md")
     cp_q("../stdlib/Mmap/docs/src/index.md", "src/stdlib/mmap.md")
     cp_q("../stdlib/SharedArrays/docs/src/index.md", "src/stdlib/sharedarrays.md")
+    cp_q("../stdlib/Base64/docs/src/index.md", "src/stdlib/base64.md")
 else
     symlink_q("../../../stdlib/DelimitedFiles/docs/src/index.md", "src/stdlib/delimitedfiles.md")
     symlink_q("../../../stdlib/Test/docs/src/index.md", "src/stdlib/test.md")
     symlink_q("../../../stdlib/Mmap/docs/src/index.md", "src/stdlib/mmap.md")
     symlink_q("../../../stdlib/SharedArrays/docs/src/index.md", "src/stdlib/sharedarrays.md")
+    symlink_q("../../../stdlib/Base64/docs/src/index.md", "src/stdlib/base64.md")
 end
 
 const PAGES = [
@@ -99,6 +101,7 @@ const PAGES = [
         "stdlib/profile.md",
         "stdlib/stacktraces.md",
         "stdlib/simd-types.md",
+        "stdlib/base64.md",
     ],
     "Developer Documentation" => [
         "devdocs/reflection.md",
@@ -133,11 +136,11 @@ const PAGES = [
     ],
 ]
 
-using DelimitedFiles, Test, Mmap, SharedArrays
+using DelimitedFiles, Test, Mmap, SharedArrays, Base64
 
 makedocs(
     build     = joinpath(pwd(), "_build/html/en"),
-    modules   = [Base, Core, BuildSysImg, DelimitedFiles, Test, Mmap, SharedArrays],
+    modules   = [Base, Core, BuildSysImg, DelimitedFiles, Test, Mmap, SharedArrays, Base64],
     clean     = false,
     doctest   = "doctest" in ARGS,
     linkcheck = "linkcheck" in ARGS,

stdlib/Base64/docs/src/index.md

@@ -0,0 +1,8 @@
+# Base64
+
+```@docs
+Base64.Base64EncodePipe
+Base64.base64encode
+Base64.Base64DecodePipe
+Base64.base64decode
+```

stdlib/Base64/src/Base64.jl

@@ -0,0 +1,26 @@
+# This file is a part of Julia. License is MIT: https://julialang.org/license
+
+module Base64
+
+#=
+export
+    Base64EncodePipe,
+    base64encode,
+    Base64DecodePipe,
+    base64decode
+=#
+
+# Base64EncodePipe is a pipe-like IO object, which converts into base64 data
+# sent to a stream. (You must close the pipe to complete the encode, separate
+# from closing the target stream).  We also have a function base64encode(f,
+# args...) which works like sprint except that it produces base64-encoded data,
+# along with base64encode(args...)  which is equivalent to base64encode(write,
+# args...), to return base64 strings.  A Base64DecodePipe object can be used to
+# decode base64-encoded data read from a stream , while function base64decode is
+# useful for decoding strings
+
+include("buffer.jl")
+include("encode.jl")
+include("decode.jl")
+
+end

stdlib/Base64/src/buffer.jl

@@ -0,0 +1,38 @@
+# This file is a part of Julia. License is MIT: https://julialang.org/license
+
+# Data buffer for pipes.
+mutable struct Buffer
+    data::Vector{UInt8}
+    ptr::Ptr{UInt8}
+    size::Int
+
+    function Buffer(bufsize)
+        data = Vector{UInt8}(bufsize)
+        return new(data, pointer(data), 0)
+    end
+end
+
+Base.empty!(buffer::Buffer) = buffer.size = 0
+Base.getindex(buffer::Buffer, i::Integer) = unsafe_load(buffer.ptr, i)
+Base.setindex!(buffer::Buffer, v::UInt8, i::Integer) = unsafe_store!(buffer.ptr, v, i)
+Base.endof(buffer::Buffer) = buffer.size
+Base.pointer(buffer::Buffer) = buffer.ptr
+capacity(buffer::Buffer) = Int(pointer(buffer.data, endof(buffer.data) + 1) - buffer.ptr)
+
+function consumed!(buffer::Buffer, n::Integer)
+    @assert n ≤ buffer.size
+    buffer.ptr += n
+    buffer.size -= n
+end
+
+function read_to_buffer(io::IO, buffer::Buffer)
+    offset = buffer.ptr - pointer(buffer.data)
+    copy!(buffer.data, 1, buffer.data, offset, buffer.size)
+    buffer.ptr = pointer(buffer.data) + buffer.size
+    if !eof(io)
+        n = min(nb_available(io), capacity(buffer) - buffer.size)
+        unsafe_read(io, buffer.ptr + buffer.size, n)
+        buffer.size += n
+    end
+    return
+end

stdlib/Base64/src/decode.jl

@@ -0,0 +1,217 @@
+# This file is a part of Julia. License is MIT: https://julialang.org/license
+
+# Generate decode table.
+const BASE64_CODE_END = 0x40
+const BASE64_CODE_PAD = 0x41
+const BASE64_CODE_IGN = 0x42
+const BASE64_DECODE = fill(BASE64_CODE_IGN, 256)
+for (i, c) in enumerate(BASE64_ENCODE)
+    BASE64_DECODE[Int(c)+1] = UInt8(i - 1)
+end
+BASE64_DECODE[Int(encodepadding())+1] = BASE64_CODE_PAD
+decode(x::UInt8) = @inbounds return BASE64_DECODE[x + 1]
+
+"""
+    Base64DecodePipe(istream)
+
+Return a new read-only I/O stream, which decodes base64-encoded data read from
+`istream`.
+
+# Examples
+```jldoctest
+julia> io = IOBuffer();
+
+julia> iob64_decode = Base64DecodePipe(io);
+
+julia> write(io, "SGVsbG8h")
+8
+
+julia> seekstart(io);
+
+julia> String(read(iob64_decode))
+"Hello!"
+```
+"""
+struct Base64DecodePipe <: IO
+    io::IO
+    buffer::Buffer
+    rest::Vector{UInt8}
+
+    function Base64DecodePipe(io::IO)
+        buffer = Buffer(512)
+        return new(io, buffer, UInt8[])
+    end
+end
+
+function Base.unsafe_read(pipe::Base64DecodePipe, ptr::Ptr{UInt8}, n::UInt)
+    p = read_until_end(pipe, ptr, n)
+    if p < ptr + n
+        throw(EOFError())
+    end
+    return nothing
+end
+
+# Read and decode as much data as possible.
+function read_until_end(pipe::Base64DecodePipe, ptr::Ptr{UInt8}, n::UInt)
+    p = ptr
+    p_end = ptr + n
+    while !isempty(pipe.rest) && p < p_end
+        unsafe_store!(p, shift!(pipe.rest))
+        p += 1
+    end
+
+    buffer = pipe.buffer
+    i = 0
+    b1 = b2 = b3 = b4 = BASE64_CODE_IGN
+    while true
+        if b1 < 0x40 && b2 < 0x40 && b3 < 0x40 && b4 < 0x40 && p + 2 < p_end
+            # fast path to decode
+            unsafe_store!(p    , b1 << 2 | b2 >> 4)
+            unsafe_store!(p + 1, b2 << 4 | b3 >> 2)
+            unsafe_store!(p + 2, b3 << 6 | b4     )
+            p += 3
+        else
+            i, p, ended = decode_slow(b1, b2, b3, b4, buffer, i, pipe.io, p, p_end - p, pipe.rest)
+            if ended
+                break
+            end
+        end
+        if p < p_end
+            if i + 4 ≤ endof(buffer)
+                b1 = decode(buffer[i+1])
+                b2 = decode(buffer[i+2])
+                b3 = decode(buffer[i+3])
+                b4 = decode(buffer[i+4])
+                i += 4
+            else
+                consumed!(buffer, i)
+                read_to_buffer(pipe.io, buffer)
+                i = 0
+                b1 = b2 = b3 = b4 = BASE64_CODE_IGN
+            end
+        else
+            break
+        end
+    end
+    consumed!(buffer, i)
+
+    return p
+end
+
+function Base.read(pipe::Base64DecodePipe, ::Type{UInt8})
+    if isempty(pipe.rest)
+        unsafe_read(pipe, convert(Ptr{UInt8}, C_NULL), 0)
+        if isempty(pipe.rest)
+            throw(EOFError())
+        end
+    end
+    return shift!(pipe.rest)
+end
+
+function Base.readbytes!(pipe::Base64DecodePipe, data::AbstractVector{UInt8}, nb::Integer=length(data))
+    filled::Int = 0
+    while filled < nb && !eof(pipe)
+        if length(data) == filled
+            resize!(data, min(length(data) * 2, nb))
+        end
+        p = pointer(data, filled + 1)
+        p_end = read_until_end(pipe, p, UInt(min(length(data), nb) - filled))
+        filled += p_end - p
+    end
+    resize!(data, filled)
+    return filled
+end
+
+Base.eof(pipe::Base64DecodePipe) = isempty(pipe.rest) && eof(pipe.io)
+Base.close(pipe::Base64DecodePipe) = nothing
+
+# Decode data from (b1, b2, b3, b5, buffer, input) into (ptr, rest).
+function decode_slow(b1, b2, b3, b4, buffer, i, input, ptr, n, rest)
+    # Skip ignore code.
+    while true
+        if b1 == BASE64_CODE_IGN
+            b1, b2, b3 = b2, b3, b4
+        elseif b2 == BASE64_CODE_IGN
+            b2, b3 = b3, b4
+        elseif b3 == BASE64_CODE_IGN
+            b3 = b4
+        elseif b4 == BASE64_CODE_IGN
+            # pass
+        else
+            break
+        end
+        if i + 1 ≤ endof(buffer)
+            b4 = decode(buffer[i+=1])
+        elseif !eof(input)
+            b4 = decode(read(input, UInt8))
+        else
+            b4 = BASE64_CODE_END
+            break
+        end
+    end
+
+    # Check the decoded quadruplet.
+    k = 0
+    if b1 < 0x40 && b2 < 0x40 && b3 < 0x40 && b4 < 0x40
+        k = 3
+    elseif b1 < 0x40 && b2 < 0x40 && b3 < 0x40 && b4 == BASE64_CODE_PAD
+        b4 = 0x00
+        k = 2
+    elseif b1 < 0x40 && b2 < 0x40 && b3 == b4 == BASE64_CODE_PAD
+        b3 = b4 = 0x00
+        k = 1
+    elseif b1 == b2 == b3 == BASE64_CODE_IGN && b4 == BASE64_CODE_END
+        b1 = b2 = b3 = b4 = 0x00
+    else
+        throw(ArgumentError("malformed base64 sequence"))
+    end
+
+    # Write output.
+    p::Ptr{UInt8} = ptr
+    p_end = ptr + n
+    function output(b)
+        if p < p_end
+            unsafe_store!(p, b)
+            p += 1
+        else
+            push!(rest, b)
+        end
+    end
+    k ≥ 1 && output(b1 << 2 | b2 >> 4)
+    k ≥ 2 && output(b2 << 4 | b3 >> 2)
+    k ≥ 3 && output(b3 << 6 | b4     )
+
+    return i, p, k == 0
+end
+
+"""
+    base64decode(string)
+
+Decode the base64-encoded `string` and returns a `Vector{UInt8}` of the decoded
+bytes.
+
+See also [`base64encode`](@ref).
+
+# Examples
+```jldoctest
+julia> b = base64decode("SGVsbG8h")
+6-element Array{UInt8,1}:
+ 0x48
+ 0x65
+ 0x6c
+ 0x6c
+ 0x6f
+ 0x21
+
+julia> String(b)
+"Hello!"
+```
+"""
+function base64decode(s)
+    b = IOBuffer(s)
+    try
+        return read(Base64DecodePipe(b))
+    finally
+        close(b)
+    end
+end