Seed Libc rng from system entropy

base/Base.jl

@@ -290,6 +290,9 @@ include("process.jl")
 include("ttyhascolor.jl")
 include("secretbuffer.jl")
 
+# RandomDevice support
+include("randomdevice.jl")
+
 # core math functions
 include("floatfuncs.jl")
 include("math.jl")

base/libc.jl

@@ -400,7 +400,7 @@ rand(::Type{Float64}) = rand(UInt32) * 2.0^-32
 
 Interface to the C `srand(seed)` function.
 """
-srand(seed=floor(Int, time()) % Cuint) = ccall(:srand, Cvoid, (Cuint,), seed)
+srand(seed=Base._make_uint_seed()) = ccall(:srand, Cvoid, (Cuint,), seed)
 
 struct Cpasswd
    username::Cstring

base/randomdevice.jl

@@ -0,0 +1,77 @@
+# This file is a part of Julia. License is MIT: https://julialang.org/license
+
+# This file contains the minimal support of RandomDevice for Base's own usage.
+# The actual RandomDevice type that makes use of this infrastructure is defined
+# in the Random stdlib.
+
+module DevRandomState
+    if !Sys.iswindows()
+        mutable struct FileRef
+            @atomic file::Union{IOStream, Nothing}
+        end
+        const DEV_RANDOM  = FileRef(nothing)
+        const DEV_URANDOM = FileRef(nothing)
+    end
+    function __init__()
+        if !Sys.iswindows()
+            @atomic DEV_RANDOM.file = nothing
+            @atomic DEV_URANDOM.file = nothing
+        end
+    end
+end
+
+if Sys.iswindows()
+    function RtlGenRandom!(A::Union{Array, Ref})
+        Base.windowserror("SystemFunction036 (RtlGenRandom)", 0 == ccall(
+            (:SystemFunction036, :Advapi32), stdcall, UInt8, (Ptr{Cvoid}, UInt32),
+              A, sizeof(A)))
+    end
+
+    # Manually implemented to work without the Random machinery
+    function _rand_uint()
+        r = Ref{Cuint}()
+        RtlGenRandom!(r)
+        return r[]
+    end
+else # !windows
+    function _get_dev_random_fd(unlimited::Bool)
+        ref = unlimited ? DevRandomState.DEV_URANDOM : DevRandomState.DEV_RANDOM
+        fd = ref.file
+        if fd === nothing
+            fd = open(unlimited ? "/dev/urandom" : "/dev/random")
+            old, ok = @atomicreplace ref.file nothing => fd
+            if !ok
+                close(fd)
+                fd = old::IOStream
+            end
+        end
+        return fd
+    end
+
+    # Manually implemented to work without the Random machinery
+    function _rand_uint()
+        return read(_get_dev_random_fd(true), Cuint)
+    end
+end # os-test
+
+function _ad_hoc_entropy()
+    println(stderr,
+        "Entropy pool not available to seed RNG; using ad-hoc entropy sources.")
+    seed = reinterpret(UInt64, time())
+    seed = hash(seed, getpid() % UInt)
+    try
+        seed = hash(seed, parse(UInt64,
+                                read(pipeline(`ifconfig`, `sha1sum`), String)[1:40],
+                                base = 16) % UInt)
+    catch
+    end
+    return seed
+end
+
+function _make_uint_seed()
+    try
+        _rand_uint()
+    catch
+        return _ad_hoc_entropy() % Cuint
+    end
+end

stdlib/Random/src/RNGs.jl

@@ -23,42 +23,20 @@ else # !windows
         RandomDevice(; unlimited::Bool=true) = new(unlimited)
     end
 
+    getfile(rd::RandomDevice) = Base._get_dev_random_fd(rd.unlimited)
+
     rand(rd::RandomDevice, sp::SamplerBoolBitInteger) = read(getfile(rd), sp[])
     rand(rd::RandomDevice, ::SamplerType{Bool}) = read(getfile(rd), UInt8) % Bool
 
-    mutable struct FileRef
-        @atomic file::Union{IOStream, Nothing}
-    end
-
-    const DEV_RANDOM  = FileRef(nothing)
-    const DEV_URANDOM = FileRef(nothing)
-
-    function getfile(rd::RandomDevice)
-        ref = rd.unlimited ? DEV_URANDOM : DEV_RANDOM
-        fd = ref.file
-        if fd === nothing
-            fd = open(rd.unlimited ? "/dev/urandom" : "/dev/random")
-            old, ok = @atomicreplace ref.file nothing => fd
-            if !ok
-                close(fd)
-                fd = old::IOStream
-            end
-        end
-        return fd
-    end
-
     show(io::IO, rd::RandomDevice) =
         print(io, RandomDevice, rd.unlimited ? "()" : "(unlimited=false)")
-
 end # os-test
 
 # NOTE: this can't be put within the if-else block above
 for T in (Bool, BitInteger_types...)
     if Sys.iswindows()
         @eval function rand!(rd::RandomDevice, A::Array{$T}, ::SamplerType{$T})
-            Base.windowserror("SystemFunction036 (RtlGenRandom)", 0 == ccall(
-                (:SystemFunction036, :Advapi32), stdcall, UInt8, (Ptr{Cvoid}, UInt32),
-                  A, sizeof(A)))
+            Base.RtlGenRandom!(A)
             A
         end
     else
@@ -332,14 +310,7 @@ function make_seed()
     catch
         println(stderr,
                 "Entropy pool not available to seed RNG; using ad-hoc entropy sources.")
-        seed = reinterpret(UInt64, time())
-        seed = hash(seed, getpid() % UInt)
-        try
-            seed = hash(seed, parse(UInt64,
-                                    read(pipeline(`ifconfig`, `sha1sum`), String)[1:40],
-                                    base = 16) % UInt)
-        catch
-        end
+        Base._ad_hoc_entropy_source()
         return make_seed(seed)
     end
 end
@@ -428,10 +399,6 @@ for T in BitInteger_types
 end
 
 function __init__()
-    @static if !Sys.iswindows()
-        @atomic DEV_RANDOM.file = nothing
-        @atomic DEV_URANDOM.file = nothing
-    end
     seed!(GLOBAL_RNG)
 end