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# This file is a part of Julia. License is MIT: https://julialang.org/license
module Base64
import Base: read, write, close, eof, empty!
export Base64EncodePipe, Base64DecodePipe, base64encode, 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
#############################################################################
"""
Base64EncodePipe(ostream)
Returns a new write-only I/O stream, which converts any bytes written to it into
base64-encoded ASCII bytes written to `ostream`.
Calling [`close`](@ref) on the `Base64EncodePipe` stream
is necessary to complete the encoding (but does not close `ostream`).
# Examples
```jldoctest
julia> io = IOBuffer();
julia> iob64_encode = Base64EncodePipe(io);
julia> write(iob64_encode, "Hello!")
6
julia> close(iob64_encode);
julia> str = String(take!(io))
"SGVsbG8h"
julia> String(base64decode(str))
"Hello!"
```
"""
mutable struct Base64EncodePipe <: IO
io::IO
# writing works in groups of 3, so we need to cache last two bytes written
b0::UInt8
b1::UInt8
nb::UInt8 # number of bytes in cache: 0, 1, or 2
function Base64EncodePipe(io::IO)
b = new(io,0,0,0)
finalizer(b, close)
return b
end
end
#############################################################################
# Based on code by Stefan Karpinski from https://github.com/hackerschool/WebSockets.jl (distributed under the same MIT license as Julia)
const b64chars = ['A':'Z';'a':'z';'0':'9';'+';'/']
const base64_pad = UInt8('=')
function b64(x::UInt8, y::UInt8, z::UInt8)
n = Int(x)<<16 | Int(y)<<8 | Int(z)
b64chars[(n >> 18) + 1],
b64chars[(n >> 12) & 0b111111 + 1],
b64chars[(n >> 6) & 0b111111 + 1],
b64chars[(n ) & 0b111111 + 1]
end
function b64(x::UInt8, y::UInt8)
a, b, c = b64(x, y, 0x0)
a, b, c, base64_pad
end
function b64(x::UInt8)
a, b = b64(x, 0x0, 0x0)
a, b, base64_pad, base64_pad
end
const sentinel = typemax(UInt8)
const revb64chars = fill(sentinel, 256)
# Fill revb64chars
for (val, ch) in enumerate(b64chars)
revb64chars[UInt8(ch)] = UInt8(val - 1)
end
# Decode a block of at least 2 and at most 4 bytes, received in encvec
# Returns the first decoded byte and stores up to two more in cache
function b64decode!(encvec::Vector{UInt8}, cache::Vector{UInt8})
if length(encvec) < 2
throw(ArgumentError("incorrect base64 format, block must be at least 2 and at most 4 bytes"))
end
@inbounds u = revb64chars[encvec[1]]
@inbounds v = revb64chars[encvec[2]]
empty!(cache)
res = (u << 2) | (v >> 4)
if length(encvec) > 2
@inbounds w = revb64chars[encvec[3]]
push!(cache, (v << 4) | (w >> 2))
end
if length(encvec) > 3
@inbounds z = revb64chars[encvec[4]]
push!(cache, (w << 6) | z)
end
res
end
#############################################################################
function unsafe_write(b::Base64EncodePipe, x::Ptr{UInt8}, n::UInt)
s = 1 # starting index
# finish any cached data to write:
if b.nb == 1
if n >= 2
write(b.io, b64(b.b0, unsafe_load(x, 1), unsafe_load(x, 2))...)
s = 3
elseif n == 1
b.b1 = unsafe_load(x, 1)
b.nb = 2
return
else
return
end
elseif b.nb == 2
if n >= 1
write(b.io, b64(b.b0, b.b1, unsafe_load(x, 1))...)
s = 2
else
return
end
end
# write all groups of three bytes:
while s + 2 <= n
write(b.io, b64(unsafe_load(x, s), unsafe_load(x, s + 1), unsafe_load(x, s + 2))...)
s += 3
end
# cache any leftover bytes:
if s + 1 == n
b.b0 = unsafe_load(x, s)
b.b1 = unsafe_load(x, s + 1)
b.nb = 2
elseif s == n
b.b0 = unsafe_load(x, s)
b.nb = 1
else
b.nb = 0
end
n
end
function write(b::Base64EncodePipe, x::UInt8)
if b.nb == 0
b.b0 = x
b.nb = 1
elseif b.nb == 1
b.b1 = x
b.nb = 2
else
write(b.io, b64(b.b0,b.b1,x)...)
b.nb = 0
end
1
end
function close(b::Base64EncodePipe)
if b.nb > 0
# write leftover bytes + padding
if b.nb == 1
write(b.io, b64(b.b0)...)
else # b.nb == 2
write(b.io, b64(b.b0, b.b1)...)
end
b.nb = 0
end
nothing
end
# like sprint, but returns base64 string
"""
base64encode(writefunc, args...)
base64encode(args...)
Given a [`write`](@ref)-like function `writefunc`, which takes an I/O stream as its first argument,
`base64encode(writefunc, args...)` calls `writefunc` to write `args...` to a base64-encoded
string, and returns the string. `base64encode(args...)` is equivalent to `base64encode(write, args...)`:
it converts its arguments into bytes using the standard [`write`](@ref) functions and returns the
base64-encoded string.
See also [`base64decode`](@ref).
"""
function base64encode(f::Function, args...)
s = IOBuffer()
b = Base64EncodePipe(s)
f(b, args...)
close(b)
String(take!(s))
end
base64encode(x...) = base64encode(write, x...)
#############################################################################
"""
Base64DecodePipe(istream)
Returns 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!"
```
"""
mutable struct Base64DecodePipe <: IO
io::IO
# reading works in blocks of 4 characters that are decoded into 3 bytes and 2 of them cached
cache::Vector{UInt8}
encvec::Vector{UInt8}
function Base64DecodePipe(io::IO)
b = new(io,[],[])
finalizer(b, close)
return b
end
end
function read(b::Base64DecodePipe, t::Type{UInt8})
if !isempty(b.cache)
return shift!(b.cache)
else
empty!(b.encvec)
while !eof(b.io) && length(b.encvec) < 4
c::UInt8 = read(b.io, t)
@inbounds if revb64chars[c] != sentinel
push!(b.encvec, c)
end
end
return b64decode!(b.encvec,b.cache)
end
end
eof(b::Base64DecodePipe) = isempty(b.cache) && eof(b.io)
close(b::Base64DecodePipe) = nothing
# Decodes a base64-encoded string
"""
base64decode(string)
Decodes 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
end # module