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std.Io.Threaded: tweak logic for use_dev_urandom

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This commit is contained in:
Andrew Kelley 2026-01-06 17:29:39 -08:00
parent 61cb5e4af9
commit 8e1850e277
1 changed files with 40 additions and 37 deletions
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77
lib/std/Io/Threaded.zig
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@ -1744,18 +1744,17 @@ const statx_use_c = std.c.versionCheck(if (builtin.abi.isAndroid())
else
.{ .major = 2, .minor = 28, .patch = 0 });
const getrandom_use_libc = @TypeOf(posix.system.getrandom) != void and (native_os != .linux or
std.c.versionCheck(if (builtin.abi.isAndroid()) .{
.major = 28,
.minor = 0,
.patch = 0,
} else .{
.major = 2,
.minor = 25,
.patch = 0,
}));
const use_libc_getrandom = std.c.versionCheck(if (builtin.abi.isAndroid()) .{
.major = 28,
.minor = 0,
.patch = 0,
} else .{
.major = 2,
.minor = 25,
.patch = 0,
});
const use_dev_urandom = !getrandom_use_libc and native_os == .linux;
const use_dev_urandom = @TypeOf(posix.system.getrandom) == void and native_os == .linux;
fn async(
userdata: ?*anyopaque,
@ -15149,9 +15148,9 @@ fn fallbackSeedWasi(seed: *[Csprng.seed_len]u8) void {
fn randomSecure(userdata: ?*anyopaque, buffer: []u8) Io.RandomSecureError!void {
const t: *Threaded = @ptrCast(@alignCast(userdata));
if (buffer.len == 0) return;
if (is_windows) {
if (buffer.len == 0) return;
// ProcessPrng from bcryptprimitives.dll has the following properties:
// * introduces a dependency on bcryptprimitives.dll, which apparently
// runs a test suite every time it is loaded
@ -15213,7 +15212,7 @@ fn randomSecure(userdata: ?*anyopaque, buffer: []u8) Io.RandomSecureError!void {
}
if (@TypeOf(posix.system.getrandom) != void) {
const getrandom = if (getrandom_use_libc) std.c.getrandom else std.os.linux.getrandom;
const getrandom = if (use_libc_getrandom) std.c.getrandom else std.os.linux.getrandom;
var i: usize = 0;
const syscall: Syscall = try .start();
while (i < buffer.len) {
@ -15244,34 +15243,38 @@ fn randomSecure(userdata: ?*anyopaque, buffer: []u8) Io.RandomSecureError!void {
}
}
if (buffer.len == 0) return;
const urandom_fd = try getRandomFd(t);
if (native_os == .linux) {
comptime assert(use_dev_urandom);
const urandom_fd = try getRandomFd(t);
var i: usize = 0;
while (buffer.len - i != 0) {
const syscall: Syscall = try .start();
const rc = posix.system.read(urandom_fd, buffer[i..].ptr, buffer.len - i);
switch (posix.errno(rc)) {
.SUCCESS => {
syscall.finish();
const n: usize = @intCast(rc);
if (n == 0) {
if (buffer.len - i != 0) {
return error.EntropyUnavailable;
} else {
return;
var i: usize = 0;
while (buffer.len - i != 0) {
const syscall: Syscall = try .start();
const rc = posix.system.read(urandom_fd, buffer[i..].ptr, buffer.len - i);
switch (posix.errno(rc)) {
.SUCCESS => {
syscall.finish();
const n: usize = @intCast(rc);
if (n == 0) {
if (buffer.len - i != 0) {
return error.EntropyUnavailable;
} else {
return;
}
}
}
i += n;
continue;
},
.INTR => {
try syscall.checkCancel();
continue;
},
else => return syscall.fail(error.EntropyUnavailable),
i += n;
continue;
},
.INTR => {
try syscall.checkCancel();
continue;
},
else => return syscall.fail(error.EntropyUnavailable),
}
}
}
return error.EntropyUnavailable;
}
fn getRandomFd(t: *Threaded) Io.RandomSecureError!posix.fd_t {