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# This file is a part of Julia. License is MIT: https://julialang.org/license
# Generate encode table.
const BASE64_ENCODE = [UInt8(x) for x in ['A':'Z'; 'a':'z'; '0':'9'; '+'; '/']]
encode(x::UInt8) = @inbounds return BASE64_ENCODE[(x & 0x3f) + 1]
encodepadding() = UInt8('=')
"""
Base64EncodePipe(ostream)
Return 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!"
```
"""
struct Base64EncodePipe <: IO
io::IO
buffer::Buffer
function Base64EncodePipe(io::IO)
# The buffer size must be at least 3.
buffer = Buffer(512)
pipe = new(io, buffer)
finalizer(_ -> close(pipe), buffer)
return pipe
end
end
function Base.unsafe_write(pipe::Base64EncodePipe, ptr::Ptr{UInt8}, n::UInt)::Int
buffer = pipe.buffer
m = buffer.size
b1, b2, b3, k = loadtriplet!(buffer, ptr, n)
@assert k ≥ m
p = ptr + k - m
if k < 3
if k == 1
buffer[1] = b1
buffer.size = 1
elseif k == 2
buffer[1] = b1
buffer[2] = b2
buffer.size = 2
end
return p - ptr
end
@assert buffer.size == 0
i = 0
p_end = ptr + n
while true
buffer[i+1] = encode(b1 >> 2 )
buffer[i+2] = encode(b1 << 4 | b2 >> 4)
buffer[i+3] = encode(b2 << 2 | b3 >> 6)
buffer[i+4] = encode( b3 )
i += 4
if p + 2 < p_end
b1 = unsafe_load(p, 1)
b2 = unsafe_load(p, 2)
b3 = unsafe_load(p, 3)
p += 3
else
break
end
if i + 4 > capacity(buffer)
unsafe_write(pipe.io, pointer(buffer), i)
i = 0
end
end
if i > 0
unsafe_write(pipe.io, pointer(buffer), i)
end
while p < p_end
buffer[buffer.size+=1] = unsafe_load(p)
p += 1
end
return p - ptr
end
function Base.write(pipe::Base64EncodePipe, x::UInt8)
buffer = pipe.buffer
buffer[buffer.size+=1] = x
if buffer.size == 3
unsafe_write(pipe, C_NULL, 0)
end
return 1
end
function Base.close(pipe::Base64EncodePipe)
b1, b2, b3, k = loadtriplet!(pipe.buffer, Ptr{UInt8}(C_NULL), UInt(0))
if k == 0
# no leftover and padding
elseif k == 1
write(pipe.io,
encode(b1 >> 2),
encode(b1 << 4),
encodepadding(),
encodepadding())
elseif k == 2
write(pipe.io,
encode( b1 >> 2),
encode(b1 << 4 | b2 >> 4),
encode(b2 << 2 ),
encodepadding())
else
@assert k == 3
write(pipe.io,
encode(b1 >> 2 ),
encode(b1 << 4 | b2 >> 4),
encode(b2 << 2 | b3 >> 6),
encode( b3 ))
end
return nothing
end
# Load three bytes from buffer and ptr.
function loadtriplet!(buffer::Buffer, ptr::Ptr{UInt8}, n::UInt)
b1 = b2 = b3 = 0x00
if buffer.size == 0
if n == 0
k = 0
elseif n == 1
b1 = unsafe_load(ptr, 1)
k = 1
elseif n == 2
b1 = unsafe_load(ptr, 1)
b2 = unsafe_load(ptr, 2)
k = 2
else
b1 = unsafe_load(ptr, 1)
b2 = unsafe_load(ptr, 2)
b3 = unsafe_load(ptr, 3)
k = 3
end
elseif buffer.size == 1
b1 = buffer[1]
if n == 0
k = 1
elseif n == 1
b2 = unsafe_load(ptr, 1)
k = 2
else
b2 = unsafe_load(ptr, 1)
b3 = unsafe_load(ptr, 2)
k = 3
end
elseif buffer.size == 2
b1 = buffer[1]
b2 = buffer[2]
if n == 0
k = 2
else
b3 = unsafe_load(ptr, 1)
k = 3
end
else
@assert buffer.size == 3
b1 = buffer[1]
b2 = buffer[2]
b3 = buffer[3]
k = 3
end
empty!(buffer)
return b1, b2, b3, k
end
"""
base64encode(writefunc, args...; context=nothing)
base64encode(args...; context=nothing)
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.
The optional keyword argument `context` can be set to `:key=>value` pair
or an `IO` or [`IOContext`](@ref) object whose attributes are used for the I/O
stream passed to `writefunc` or `write`.
See also [`base64decode`](@ref).
"""
function base64encode(f::Function, args...; context=nothing)
s = IOBuffer()
b = Base64EncodePipe(s)
if context === nothing
f(b, args...)
else
f(IOContext(b, context), args...)
end
close(b)
return String(take!(s))
end
base64encode(args...; context=nothing) = base64encode(write, args...; context=context)
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