c.jl
# This file is a part of Julia. License is MIT: https://julialang.org/license
# definitions related to C interface
import Core.Intrinsics: cglobal, bitcast
"""
cglobal((symbol, library) [, type=Cvoid])
Obtain a pointer to a global variable in a C-exported shared library, specified exactly as
in [`ccall`](@ref).
Returns a `Ptr{Type}`, defaulting to `Ptr{Cvoid}` if no `Type` argument is
supplied.
The values can be read or written by [`unsafe_load`](@ref) or [`unsafe_store!`](@ref),
respectively.
"""
cglobal
"""
cfunction(f::Function, returntype::Type, argtypes::Type) -> Ptr{Cvoid}
Generate C-callable function pointer from the Julia function `f`. Type annotation of the return
value in the callback function is a must for situations where Julia cannot infer the return
type automatically.
# Examples
```julia-repl
julia> function foo(x::Int, y::Int)
return x + y
end
julia> cfunction(foo, Int, Tuple{Int,Int})
Ptr{Cvoid} @0x000000001b82fcd0
```
"""
cfunction(f, r, a) = ccall(:jl_function_ptr, Ptr{Cvoid}, (Any, Any, Any), f, r, a)
if ccall(:jl_is_char_signed, Ref{Bool}, ())
const Cchar = Int8
else
const Cchar = UInt8
end
"""
Cchar
Equivalent to the native `char` c-type.
"""
Cchar
# The ccall here is equivalent to Sys.iswindows(), but that's not defined yet
@static if ccall(:jl_get_UNAME, Any, ()) === :NT
const Clong = Int32
const Culong = UInt32
const Cwchar_t = UInt16
else
const Clong = Int
const Culong = UInt
const Cwchar_t = Int32
end
"""
Clong
Equivalent to the native `signed long` c-type.
"""
Clong
"""
Culong
Equivalent to the native `unsigned long` c-type.
"""
Culong
"""
Cwchar_t
Equivalent to the native `wchar_t` c-type ([`Int32`](@ref)).
"""
Cwchar_t
@static if ccall(:jl_get_UNAME, Any, ()) !== :NT
const sizeof_mode_t = ccall(:jl_sizeof_mode_t, Cint, ())
if sizeof_mode_t == 2
const Cmode_t = Int16
elseif sizeof_mode_t == 4
const Cmode_t = Int32
elseif sizeof_mode_t == 8
const Cmode_t = Int64
end
end
# construction from pointers
Cstring(p::Union{Ptr{Int8},Ptr{UInt8},Ptr{Cvoid}}) = bitcast(Cstring, p)
Cwstring(p::Union{Ptr{Cwchar_t},Ptr{Cvoid}}) = bitcast(Cwstring, p)
(::Type{Ptr{T}})(p::Cstring) where {T<:Union{Int8,UInt8,Cvoid}} = bitcast(Ptr{T}, p)
(::Type{Ptr{T}})(p::Cwstring) where {T<:Union{Cwchar_t,Cvoid}} = bitcast(Ptr{Cwchar_t}, p)
convert(::Type{Cstring}, p::Union{Ptr{Int8},Ptr{UInt8},Ptr{Cvoid}}) = Cstring(p)
convert(::Type{Cwstring}, p::Union{Ptr{Cwchar_t},Ptr{Cvoid}}) = Cwstring(p)
convert(::Type{Ptr{T}}, p::Cstring) where {T<:Union{Int8,UInt8,Cvoid}} = Ptr{T}(p)
convert(::Type{Ptr{T}}, p::Cwstring) where {T<:Union{Cwchar_t,Cvoid}} = Ptr{T}(p)
"""
pointer(array [, index])
Get the native address of an array or string element. Be careful to ensure that a Julia
reference to `a` exists as long as this pointer will be used. This function is "unsafe" like
`unsafe_convert`.
Calling `Ref(array[, index])` is generally preferable to this function.
"""
function pointer end
pointer(p::Cstring) = convert(Ptr{UInt8}, p)
pointer(p::Cwstring) = convert(Ptr{Cwchar_t}, p)
# comparisons against pointers (mainly to support `cstr==C_NULL`)
==(x::Union{Cstring,Cwstring}, y::Ptr) = pointer(x) == y
==(x::Ptr, y::Union{Cstring,Cwstring}) = x == pointer(y)
unsafe_string(s::Cstring) = unsafe_string(convert(Ptr{UInt8}, s))
# convert strings to String etc. to pass as pointers
cconvert(::Type{Cstring}, s::String) = s
cconvert(::Type{Cstring}, s::AbstractString) =
cconvert(Cstring, String(s)::String)
function cconvert(::Type{Cwstring}, s::AbstractString)
v = transcode(Cwchar_t, String(s))
!isempty(v) && v[end] == 0 || push!(v, 0)
return v
end
eltype(::Type{Cstring}) = UInt8
eltype(::Type{Cwstring}) = Cwchar_t
containsnul(p::Ptr, len) =
C_NULL != ccall(:memchr, Ptr{Cchar}, (Ptr{Cchar}, Cint, Csize_t), p, 0, len)
containsnul(s::String) = containsnul(unsafe_convert(Ptr{Cchar}, s), sizeof(s))
containsnul(s::AbstractString) = '\0' in s
function unsafe_convert(::Type{Cstring}, s::Union{String,AbstractVector{UInt8}})
p = unsafe_convert(Ptr{Cchar}, s)
containsnul(p, sizeof(s)) &&
throw(ArgumentError("embedded NULs are not allowed in C strings: $(repr(s))"))
return Cstring(p)
end
function unsafe_convert(::Type{Cwstring}, v::Vector{Cwchar_t})
for i = 1:length(v)-1
v[i] == 0 &&
throw(ArgumentError("embedded NULs are not allowed in C strings: $(repr(v))"))
end
v[end] == 0 ||
throw(ArgumentError("C string data must be NUL terminated: $(repr(v))"))
p = unsafe_convert(Ptr{Cwchar_t}, v)
return Cwstring(p)
end
# symbols are guaranteed not to contain embedded NUL
cconvert(::Type{Cstring}, s::Symbol) = s
unsafe_convert(::Type{Cstring}, s::Symbol) = Cstring(unsafe_convert(Ptr{Cchar}, s))
@static if ccall(:jl_get_UNAME, Any, ()) === :NT
"""
Base.cwstring(s)
Converts a string `s` to a NUL-terminated `Vector{Cwchar_t}`, suitable for passing to C
functions expecting a `Ptr{Cwchar_t}`. The main advantage of using this over the implicit
conversion provided by `Cwstring` is if the function is called multiple times with the
same argument.
This is only available on Windows.
"""
function cwstring(s::AbstractString)
bytes = codeunits(String(s))
0 in bytes && throw(ArgumentError("embedded NULs are not allowed in C strings: $(repr(s))"))
return push!(transcode(UInt16, bytes), 0)
end
end
# transcoding between data in UTF-8 and UTF-16 for Windows APIs,
# and also UTF-32 for APIs using Cwchar_t on other platforms.
"""
transcode(T, src)
Convert string data between Unicode encodings. `src` is either a
`String` or a `Vector{UIntXX}` of UTF-XX code units, where
`XX` is 8, 16, or 32. `T` indicates the encoding of the return value:
`String` to return a (UTF-8 encoded) `String` or `UIntXX`
to return a `Vector{UIntXX}` of UTF-`XX` data. (The alias `Cwchar_t`
can also be used as the integer type, for converting `wchar_t*` strings
used by external C libraries.)
The `transcode` function succeeds as long as the input data can be
reasonably represented in the target encoding; it always succeeds for
conversions between UTF-XX encodings, even for invalid Unicode data.
Only conversion to/from UTF-8 is currently supported.
"""
function transcode end
transcode(::Type{T}, src::AbstractVector{T}) where {T<:Union{UInt8,UInt16,UInt32,Int32}} = src
transcode(::Type{T}, src::String) where {T<:Union{Int32,UInt32}} = T[T(c) for c in src]
transcode(::Type{T}, src::Union{Vector{UInt8},CodeUnits{UInt8,String}}) where {T<:Union{Int32,UInt32}} =
transcode(T, String(src))
function transcode(::Type{UInt8}, src::Vector{<:Union{Int32,UInt32}})
buf = IOBuffer()
for c in src; print(buf, Char(c)); end
take!(buf)
end
transcode(::Type{String}, src::String) = src
transcode(T, src::String) = transcode(T, codeunits(src))
transcode(::Type{String}, src) = String(transcode(UInt8, src))
function transcode(::Type{UInt16}, src::Union{Vector{UInt8},CodeUnits{UInt8,String}})
dst = UInt16[]
i, n = 1, length(src)
n > 0 || return dst
sizehint!(dst, 2n)
a = src[1]
while true
if i < n && -64 <= a % Int8 <= -12 # multi-byte character
b = src[i += 1]
if -64 <= (b % Int8) || a == 0xf4 && 0x8f < b
# invalid UTF-8 (non-continuation or too-high code point)
push!(dst, a)
a = b; continue
elseif a < 0xe0 # 2-byte UTF-8
push!(dst, xor(0x3080, UInt16(a) << 6, b))
elseif i < n # 3/4-byte character
c = src[i += 1]
if -64 <= (c % Int8) # invalid UTF-8 (non-continuation)
push!(dst, a, b)
a = c; continue
elseif a < 0xf0 # 3-byte UTF-8
push!(dst, xor(0x2080, UInt16(a) << 12, UInt16(b) << 6, c))
elseif i < n
d = src[i += 1]
if -64 <= (d % Int8) # invalid UTF-8 (non-continuation)
push!(dst, a, b, c)
a = d; continue
elseif a == 0xf0 && b < 0x90 # overlong encoding
push!(dst, xor(0x2080, UInt16(b) << 12, UInt16(c) << 6, d))
else # 4-byte UTF-8
push!(dst, 0xe5b8 + (UInt16(a) << 8) + (UInt16(b) << 2) + (c >> 4),
xor(0xdc80, UInt16(c & 0xf) << 6, d))
end
else # too short
push!(dst, a, b, c)
break
end
else # too short
push!(dst, a, b)
break
end
else # ASCII or invalid UTF-8 (continuation byte or too-high code point)
push!(dst, a)
end
i < n || break
a = src[i += 1]
end
return dst
end
function transcode(::Type{UInt8}, src::Vector{UInt16})
n = length(src)
n == 0 && return UInt8[]
# Precompute m = sizeof(dst). This involves annoying duplication
# of the loop over the src array. However, this is not just an
# optimization: it is problematic for security reasons to grow
# dst dynamically, because Base.winprompt uses this function to
# convert passwords to UTF-8 and we don't want to make unintentional
# copies of the password data.
a = src[1]
i, m = 1, 0
while true
if a < 0x80
m += 1
elseif a < 0x800 # 2-byte UTF-8
m += 2
elseif a & 0xfc00 == 0xd800 && i < length(src)
b = src[i += 1]
if (b & 0xfc00) == 0xdc00 # 2-unit UTF-16 sequence => 4-byte UTF-8
m += 4
else
m += 3
a = b; continue
end
else
# 1-unit high UTF-16 or unpaired high surrogate
# either way, encode as 3-byte UTF-8 code point
m += 3
end
i < n || break
a = src[i += 1]
end
dst = StringVector(m)
a = src[1]
i, j = 1, 0
while true
if a < 0x80 # ASCII
dst[j += 1] = a % UInt8
elseif a < 0x800 # 2-byte UTF-8
dst[j += 1] = 0xc0 | ((a >> 6) % UInt8)
dst[j += 1] = 0x80 | ((a % UInt8) & 0x3f)
elseif a & 0xfc00 == 0xd800 && i < n
b = src[i += 1]
if (b & 0xfc00) == 0xdc00
# 2-unit UTF-16 sequence => 4-byte UTF-8
a += 0x2840
dst[j += 1] = 0xf0 | ((a >> 8) % UInt8)
dst[j += 1] = 0x80 | ((a % UInt8) >> 2)
dst[j += 1] = xor(0xf0, ((a % UInt8) << 4) & 0x3f, (b >> 6) % UInt8)
dst[j += 1] = 0x80 | ((b % UInt8) & 0x3f)
else
dst[j += 1] = 0xe0 | ((a >> 12) % UInt8)
dst[j += 1] = 0x80 | (((a >> 6) % UInt8) & 0x3f)
dst[j += 1] = 0x80 | ((a % UInt8) & 0x3f)
a = b; continue
end
else
# 1-unit high UTF-16 or unpaired high surrogate
# either way, encode as 3-byte UTF-8 code point
dst[j += 1] = 0xe0 | ((a >> 12) % UInt8)
dst[j += 1] = 0x80 | (((a >> 6) % UInt8) & 0x3f)
dst[j += 1] = 0x80 | ((a % UInt8) & 0x3f)
end
i < n || break
a = src[i += 1]
end
return dst
end
# deferring (or un-deferring) ctrl-c handler for external C code that
# is not interrupt safe (see also issue #2622). The sigatomic_begin/end
# functions should always be called in matched pairs, ideally via:
# disable_sigint() do .. end
# reennable_sigint is provided so that immediate ctrl-c handling is
# re-enabled within a sigatomic region, e.g. inside a Julia callback function
# within a long-running C routine.
sigatomic_begin() = ccall(:jl_sigatomic_begin, Cvoid, ())
sigatomic_end() = ccall(:jl_sigatomic_end, Cvoid, ())
"""
disable_sigint(f::Function)
Disable Ctrl-C handler during execution of a function on the current task,
for calling external code that may call julia code that is not interrupt safe.
Intended to be called using `do` block syntax as follows:
disable_sigint() do
# interrupt-unsafe code
...
end
This is not needed on worker threads (`Threads.threadid() != 1`) since the
`InterruptException` will only be delivered to the master thread.
External functions that do not call julia code or julia runtime
automatically disable sigint during their execution.
"""
function disable_sigint(f::Function)
sigatomic_begin()
res = f()
# Exception unwind sigatomic automatically
sigatomic_end()
res
end
"""
reenable_sigint(f::Function)
Re-enable Ctrl-C handler during execution of a function.
Temporarily reverses the effect of `disable_sigint`.
"""
function reenable_sigint(f::Function)
sigatomic_end()
res = f()
# Exception unwind sigatomic automatically
sigatomic_begin()
res
end
function ccallable(f::Function, rt::Type, argt::Type, name::Union{AbstractString,Symbol}=string(f))
ccall(:jl_extern_c, Cvoid, (Any, Any, Any, Cstring), f, rt, argt, name)
end
function expand_ccallable(rt, def)
if isa(def,Expr) && (def.head === :(=) || def.head === :function)
sig = def.args[1]
if sig.head === :(::)
if rt === nothing
rt = sig.args[2]
end
sig = sig.args[1]
end
if rt === nothing
error("@ccallable requires a return type")
end
if sig.head === :call
name = sig.args[1]
at = map(sig.args[2:end]) do a
if isa(a,Expr) && a.head === :(::)
a.args[2]
else
:Any
end
end
return quote
$(esc(def))
ccallable($(esc(name)), $(esc(rt)), $(Expr(:curly, :Tuple, map(esc, at)...)), $(string(name)))
end
end
end
error("expected method definition in @ccallable")
end
macro ccallable(def)
expand_ccallable(nothing, def)
end
macro ccallable(rt, def)
expand_ccallable(rt, def)
end
