WIP: refactor(hal): migrate from cstr_from_bytes_until_nul to `CStr…

…::from_bytes_until_nul`

Not mergeable until MSRV is Rust 1.69.

wgpu-hal/src/auxil/mod.rs

@@ -116,26 +116,6 @@ impl crate::TextureCopy {
     }
 }
 
-/// Construct a `CStr` from a byte slice, up to the first zero byte.
-///
-/// Return a `CStr` extending from the start of `bytes` up to and
-/// including the first zero byte. If there is no zero byte in
-/// `bytes`, return `None`.
-///
-/// This can be removed when `CStr::from_bytes_until_nul` is stabilized.
-/// ([#95027](https://github.com/rust-lang/rust/issues/95027))
-#[allow(dead_code)]
-pub(crate) fn cstr_from_bytes_until_nul(bytes: &[u8]) -> Option<&std::ffi::CStr> {
-    // Use a more safe implementation of [what `std` does].
-    //
-    // [what `std` does]: https://doc.rust-lang.org/1.69.0/src/core/ffi/c_str.rs.html#329-340
-    if let Some(nul_pos) = bytes.iter().copied().position(|b| b == 0) {
-        Some(std::ffi::CStr::from_bytes_with_nul(bytes.get(..nul_pos + 1).unwrap()).unwrap())
-    } else {
-        None
-    }
-}
-
 #[allow(dead_code)]
 pub(crate) fn cstr_from_chars_until_nul(chars: &[std::os::raw::c_char]) -> Option<&std::ffi::CStr> {
     if chars.contains(&0) {

wgpu-hal/src/vulkan/instance.rs

@@ -565,7 +565,6 @@ impl Drop for super::InstanceShared {
 impl crate::Instance<super::Api> for super::Instance {
     unsafe fn init(desc: &crate::InstanceDescriptor) -> Result<Self, crate::InstanceError> {
         profiling::scope!("Init Vulkan Backend");
-        use crate::auxil::cstr_from_bytes_until_nul;
 
         let entry = unsafe {
             profiling::scope!("Load vk library");
@@ -631,9 +630,9 @@ impl crate::Instance<super::Api> for super::Instance {
             instance_layers: &'layers [vk::LayerProperties],
             name: &CStr,
         ) -> Option<&'layers vk::LayerProperties> {
-            instance_layers
-                .iter()
-                .find(|inst_layer| cstr_from_bytes_until_nul(&inst_layer.layer_name) == Some(name))
+            instance_layers.iter().find(|inst_layer| {
+                CStr::from_bytes_until_nul(&inst_layer.layer_name).ok() == Some(name)
+            })
         }
 
         let nv_optimus_layer = CStr::from_bytes_with_nul(b"VK_LAYER_NV_optimus\0").unwrap();
@@ -656,7 +655,7 @@ impl crate::Instance<super::Api> for super::Instance {
                     // Put the callback data on the heap, to ensure it will never be
                     // moved.
                     let callback_data = Box::new(super::DebugUtilsMessengerUserData {
-                        validation_layer_description: cstr_from_bytes_until_nul(
+                        validation_layer_description: CStr::from_bytes_until_nul(
                             &layer_properties.description,
                         )
                         .unwrap()