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std.Random: Make ptr optional to avoid UB when comparing Random instances

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The same change as the one made to std.Allocator, and for the same reasons. However, this change is precautionary rather than addressing a known instance of UB.
This commit is contained in:
Ryan Liptak 2024-11-24 18:26:30 -08:00
parent be6b89069b
commit 52a6e355c4
2 changed files with 7 additions and 5 deletions
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10
lib/std/Random.zig
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@ -29,8 +29,10 @@ pub const RomuTrio = @import("Random/RomuTrio.zig");
pub const SplitMix64 = @import("Random/SplitMix64.zig");
pub const ziggurat = @import("Random/ziggurat.zig");
ptr: *anyopaque,
fillFn: *const fn (ptr: *anyopaque, buf: []u8) void,
/// The type erased pointer to the random implementation.
/// If null, the random implementation has no associated state.
ptr: ?*anyopaque,
fillFn: *const fn (ptr: ?*anyopaque, buf: []u8) void,
pub fn init(pointer: anytype, comptime fillFn: fn (ptr: @TypeOf(pointer), buf: []u8) void) Random {
const Ptr = @TypeOf(pointer);
@ -38,8 +40,8 @@ pub fn init(pointer: anytype, comptime fillFn: fn (ptr: @TypeOf(pointer), buf: [
assert(@typeInfo(Ptr).pointer.size == .One); // Must be a single-item pointer
assert(@typeInfo(@typeInfo(Ptr).pointer.child) == .@"struct"); // Must point to a struct
const gen = struct {
fn fill(ptr: *anyopaque, buf: []u8) void {
const self: Ptr = @ptrCast(@alignCast(ptr));
fn fill(ptr: ?*anyopaque, buf: []u8) void {
const self: Ptr = @ptrCast(@alignCast(ptr.?));
fillFn(self, buf);
}
};

2
lib/std/crypto/tlcsprng.zig
View File

@ -12,7 +12,7 @@ const posix = std.posix;
/// We use this as a layer of indirection because global const pointers cannot
/// point to thread-local variables.
pub const interface: std.Random = .{
.ptr = undefined,
.ptr = null,
.fillFn = tlsCsprngFill,
};