From 8ebe174b1f68f00ff102611f0a35af0fb3fcd73d Mon Sep 17 00:00:00 2001
From: Chris Denton <chris@chrisdenton.dev>
Date: Wed, 26 Mar 2025 14:27:11 +0000
Subject: [PATCH] Use getrandom for randomness

---
 Cargo.lock     | 41 +++++++++++++++++++++++++++++++++++++++--
 Cargo.toml     |  3 +++
 src/windows.rs | 30 ++----------------------------
 3 files changed, 44 insertions(+), 30 deletions(-)

diff --git a/Cargo.lock b/Cargo.lock
index bbb8569..f6fffe3 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -36,10 +36,23 @@ version = "2.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "25cbce373ec4653f1a01a31e8a5e5ec0c622dc27ff9c4e6606eefef5cbbed4a5"
 
+[[package]]
+name = "getrandom"
+version = "0.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "73fea8450eea4bac3940448fb7ae50d91f034f941199fcd9d909a5a07aa455f0"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "r-efi",
+ "wasi",
+]
+
 [[package]]
 name = "jobserver"
 version = "0.1.32"
 dependencies = [
+ "getrandom",
  "libc",
  "nix",
  "tempfile",
@@ -47,9 +60,9 @@ dependencies = [
 
 [[package]]
 name = "libc"
-version = "0.2.153"
+version = "0.2.171"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9c198f91728a82281a64e1f4f9eeb25d82cb32a5de251c6bd1b5154d63a8e7bd"
+checksum = "c19937216e9d3aa9956d9bb8dfc0b0c8beb6058fc4f7a4dc4d850edf86a237d6"
 
 [[package]]
 name = "linux-raw-sys"
@@ -69,6 +82,12 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "r-efi"
+version = "5.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "74765f6d916ee2faa39bc8e68e4f3ed8949b48cccdac59983d287a7cb71ce9c5"
+
 [[package]]
 name = "rustix"
 version = "0.38.31"
@@ -94,6 +113,15 @@ dependencies = [
  "windows-sys",
 ]
 
+[[package]]
+name = "wasi"
+version = "0.14.2+wasi-0.2.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9683f9a5a998d873c0d21fcbe3c083009670149a8fab228644b8bd36b2c48cb3"
+dependencies = [
+ "wit-bindgen-rt",
+]
+
 [[package]]
 name = "windows-sys"
 version = "0.52.0"
@@ -159,3 +187,12 @@ name = "windows_x86_64_msvc"
 version = "0.52.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "dff9641d1cd4be8d1a070daf9e3773c5f67e78b4d9d42263020c057706765c04"
+
+[[package]]
+name = "wit-bindgen-rt"
+version = "0.39.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6f42320e61fe2cfd34354ecb597f86f413484a798ba44a8ca1165c58d42da6c1"
+dependencies = [
+ "bitflags",
+]
diff --git a/Cargo.toml b/Cargo.toml
index 78df256..a98c10d 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -18,6 +18,9 @@ libc = "0.2.87"
 [target.'cfg(unix)'.dev-dependencies]
 nix = { version = "0.28.0", features = ["fs"] }
 
+[target.'cfg(windows)'.dependencies]
+getrandom = { version = "0.3.2", features = ["std"] }
+
 [dev-dependencies]
 tempfile = "3.10.1"
 
diff --git a/src/windows.rs b/src/windows.rs
index 0ddfa2e..550f658 100644
--- a/src/windows.rs
+++ b/src/windows.rs
@@ -67,31 +67,6 @@ extern "system" {
     fn WaitForSingleObject(hHandle: HANDLE, dwMilliseconds: DWORD) -> DWORD;
 }
 
-#[link(name = "advapi32")]
-extern "system" {
-    #[link_name = "SystemFunction036"]
-    fn RtlGenRandom(RandomBuffer: *mut u8, RandomBufferLength: u32) -> u8;
-}
-
-// Note that we ideally would use the `getrandom` crate, but unfortunately
-// that causes build issues when this crate is used in rust-lang/rust (see
-// rust-lang/rust#65014 for more information). As a result we just inline
-// the pretty simple Windows-specific implementation of generating
-// randomness.
-fn getrandom(dest: &mut [u8]) -> io::Result<()> {
-    // Prevent overflow of u32
-    for chunk in dest.chunks_mut(u32::MAX as usize) {
-        let ret = unsafe { RtlGenRandom(chunk.as_mut_ptr(), chunk.len() as u32) };
-        if ret == 0 {
-            return Err(io::Error::new(
-                io::ErrorKind::Other,
-                "failed to generate random bytes",
-            ));
-        }
-    }
-    Ok(())
-}
-
 impl Client {
     pub fn new(limit: usize) -> io::Result<Client> {
         // Try a bunch of random semaphore names until we get a unique one,
@@ -103,9 +78,8 @@ impl Client {
         // slot and then immediately acquire it (without ever releaseing it
         // back).
         for _ in 0..100 {
-            let mut bytes = [0; 4];
-            getrandom(&mut bytes)?;
-            let mut name = format!("__rust_jobserver_semaphore_{}\0", u32::from_ne_bytes(bytes));
+            let bytes = getrandom::u32()?;
+            let mut name = format!("__rust_jobserver_semaphore_{}\0", bytes);
             unsafe {
                 let create_limit = if limit == 0 { 1 } else { limit };
                 let r = CreateSemaphoreA(