1 files changed, 23 insertions, 0 deletions
diff --git a/third_party/rust/tinystr/src/helpers.rs b/third_party/rust/tinystr/src/helpers.rs
new file mode 100644
index 0000000000..9b5be84152
--- /dev/null
+++ b/third_party/rust/tinystr/src/helpers.rs
@@ -0,0 +1,23 @@
+use std::num::NonZeroU32;
+use std::ptr::copy_nonoverlapping;
+
+use super::Error;
+
+#[inline(always)]
+pub(crate) unsafe fn make_4byte_bytes(
+    bytes: &[u8],
+    len: usize,
+    mask: u32,
+) -> Result<NonZeroU32, Error> {
+    // Mask is always supplied as little-endian.
+    let mask = u32::from_le(mask);
+    let mut word: u32 = 0;
+    copy_nonoverlapping(bytes.as_ptr(), &mut word as *mut u32 as *mut u8, len);
+    if (word & mask) != 0 {
+        return Err(Error::NonAscii);
+    }
+    if ((mask - word) & mask) != 0 {
+        return Err(Error::InvalidNull);
+    }
+    Ok(NonZeroU32::new_unchecked(word))
+}