refactor(hal): split into cstr_from_{bytes,chars}_until_nul

wgpu-hal/src/auxil/mod.rs

@@ -125,13 +125,25 @@ impl crate::TextureCopy {
 /// 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: &[std::os::raw::c_char]) -> Option<&std::ffi::CStr> {
-    if bytes.contains(&0) {
+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) {
         // Safety for `CStr::from_ptr`:
         // - We've ensured that the slice does contain a null terminator.
         // - The range is valid to read, because the slice covers it.
         // - The memory won't be changed, because the slice borrows it.
-        unsafe { Some(std::ffi::CStr::from_ptr(bytes.as_ptr())) }
+        unsafe { Some(std::ffi::CStr::from_ptr(chars.as_ptr())) }
     } else {
         None
     }

wgpu-hal/src/vulkan/adapter.rs

@@ -665,10 +665,10 @@ impl PhysicalDeviceCapabilities {
     }
 
     pub fn supports_extension(&self, extension: &CStr) -> bool {
-        use crate::auxil::cstr_from_bytes_until_nul;
+        use crate::auxil::cstr_from_chars_until_nul;
         self.supported_extensions
             .iter()
-            .any(|ep| cstr_from_bytes_until_nul(&ep.extension_name) == Some(extension))
+            .any(|ep| cstr_from_chars_until_nul(&ep.extension_name) == Some(extension))
     }
 
     /// Map `requested_features` to the list of Vulkan extension strings required to create the logical device.
@@ -1070,14 +1070,14 @@ impl super::Instance {
         &self,
         phd: vk::PhysicalDevice,
     ) -> Option<crate::ExposedAdapter<super::Api>> {
-        use crate::auxil::cstr_from_bytes_until_nul;
+        use crate::auxil::cstr_from_chars_until_nul;
         use crate::auxil::db;
 
         let (phd_capabilities, phd_features) = self.shared.inspect(phd);
 
         let info = wgt::AdapterInfo {
             name: {
-                cstr_from_bytes_until_nul(&phd_capabilities.properties.device_name)
+                cstr_from_chars_until_nul(&phd_capabilities.properties.device_name)
                     .and_then(|info| info.to_str().ok())
                     .unwrap_or("?")
                     .to_owned()
@@ -1096,7 +1096,7 @@ impl super::Instance {
                 phd_capabilities
                     .driver
                     .as_ref()
-                    .and_then(|driver| cstr_from_bytes_until_nul(&driver.driver_name))
+                    .and_then(|driver| cstr_from_chars_until_nul(&driver.driver_name))
                     .and_then(|name| name.to_str().ok())
                     .unwrap_or("?")
                     .to_owned()
@@ -1105,7 +1105,7 @@ impl super::Instance {
                 phd_capabilities
                     .driver
                     .as_ref()
-                    .and_then(|driver| cstr_from_bytes_until_nul(&driver.driver_info))
+                    .and_then(|driver| cstr_from_chars_until_nul(&driver.driver_info))
                     .and_then(|name| name.to_str().ok())
                     .unwrap_or("?")
                     .to_owned()

wgpu-hal/src/vulkan/instance.rs

@@ -283,7 +283,7 @@ impl super::Instance {
         // Only keep available extensions.
         extensions.retain(|&ext| {
             if instance_extensions.iter().any(|inst_ext| {
-                crate::auxil::cstr_from_bytes_until_nul(&inst_ext.extension_name) == Some(ext)
+                crate::auxil::cstr_from_chars_until_nul(&inst_ext.extension_name) == Some(ext)
             }) {
                 true
             } else {