refactor(ironrdp-web): fix indexing_slicing clippy lint warnings

Cargo.toml

@@ -93,6 +93,7 @@ ptr_cast_constness = "warn"
 
 # == Correctness == #
 as_conversions = "warn"
+# indexing_slicing = "warn" TODO: enable this lint project wide.
 cast_lossless = "warn"
 cast_possible_truncation = "warn"
 cast_possible_wrap = "warn"

crates/ironrdp-web/src/canvas.rs

@@ -45,10 +45,8 @@ impl Canvas {
         let region_height = region.height();
 
         let mut src = buffer.chunks_exact(4).map(|pixel| {
-            let r = pixel[0];
-            let g = pixel[1];
-            let b = pixel[2];
-            u32::from_be_bytes([0, r, g, b])
+            let [r, g, b] = pixel.first_chunk::<3>().expect("cannot be out of bounds");
+            u32::from_be_bytes([0, *r, *g, *b])
         });
 
         let mut dst = self.surface.buffer_mut().expect("surface buffer");

crates/ironrdp-web/src/image.rs

@@ -1,9 +1,13 @@
 #![allow(clippy::arithmetic_side_effects)]
 
+use anyhow::Context as _;
 use ironrdp::pdu::geometry::{InclusiveRectangle, Rectangle as _};
 use ironrdp::session::image::DecodedImage;
 
-pub(crate) fn extract_partial_image(image: &DecodedImage, region: InclusiveRectangle) -> (InclusiveRectangle, Vec<u8>) {
+pub(crate) fn extract_partial_image(
+    image: &DecodedImage,
+    region: InclusiveRectangle,
+) -> anyhow::Result<(InclusiveRectangle, Vec<u8>)> {
     // PERF: needs actual benchmark to find a better heuristic
     if region.height() > 64 || region.width() > 512 {
         extract_whole_rows(image, region)
@@ -13,7 +17,10 @@ pub(crate) fn extract_partial_image(image: &DecodedImage, region: InclusiveRecta
 }
 
 // Faster for low-height and smaller images
-fn extract_smallest_rectangle(image: &DecodedImage, region: InclusiveRectangle) -> (InclusiveRectangle, Vec<u8>) {
+fn extract_smallest_rectangle(
+    image: &DecodedImage,
+    region: InclusiveRectangle,
+) -> anyhow::Result<(InclusiveRectangle, Vec<u8>)> {
     let pixel_size = usize::from(image.pixel_format().bytes_per_pixel());
 
     let image_width = usize::from(image.width());
@@ -33,20 +40,32 @@ fn extract_smallest_rectangle(image: &DecodedImage, region: InclusiveRectangle)
     for row in 0..region_height {
         let src_begin = image_stride * (region_top + row) + region_left * pixel_size;
         let src_end = src_begin + region_stride;
-        let src_slice = &src[src_begin..src_end];
+        let src_slice = src.get(src_begin..src_end).with_context(|| {
+            format!(
+                "invalid region {region:?} for image with dimensions {}x{}",
+                image.width(),
+                image.height()
+            )
+        })?;
 
         let target_begin = region_stride * row;
         let target_end = target_begin + region_stride;
-        let target_slice = &mut dst[target_begin..target_end];
+        let target_slice = dst.get_mut(target_begin..target_end).expect(
+            "destination buffer sized correctly based on region dimensions; \
+                     target slice indices must be in-bounds",
+        );
 
         target_slice.copy_from_slice(src_slice);
     }
 
-    (region, dst)
+    Ok((region, dst))
 }
 
 // Faster for high-height and bigger images
-fn extract_whole_rows(image: &DecodedImage, region: InclusiveRectangle) -> (InclusiveRectangle, Vec<u8>) {
+fn extract_whole_rows(
+    image: &DecodedImage,
+    region: InclusiveRectangle,
+) -> anyhow::Result<(InclusiveRectangle, Vec<u8>)> {
     let pixel_size = usize::from(image.pixel_format().bytes_per_pixel());
 
     let image_width = usize::from(image.width());
@@ -60,7 +79,16 @@ fn extract_whole_rows(image: &DecodedImage, region: InclusiveRectangle) -> (Incl
     let src_begin = region_top * image_stride;
     let src_end = (region_bottom + 1) * image_stride;
 
-    let dst = src[src_begin..src_end].to_vec();
+    let dst = src
+        .get(src_begin..src_end)
+        .with_context(|| {
+            format!(
+                "invalid region {region:?} for image with dimensions {}x{}",
+                image.width(),
+                image.height()
+            )
+        })?
+        .to_vec();
 
     let wider_region = InclusiveRectangle {
         left: 0,
@@ -69,5 +97,5 @@ fn extract_whole_rows(image: &DecodedImage, region: InclusiveRectangle) -> (Incl
         bottom: region.bottom,
     };
 
-    (wider_region, dst)
+    Ok((wider_region, dst))
 }

crates/ironrdp-web/src/session.rs

@@ -603,7 +603,7 @@ impl iron_remote_desktop::Session for Session {
                     }
                     ActiveStageOutput::GraphicsUpdate(region) => {
                         // PERF: some copies and conversion could be optimized
-                        let (region, buffer) = extract_partial_image(&image, region);
+                        let (region, buffer) = extract_partial_image(&image, region)?;
                         gui.draw(&buffer, region).context("draw updated region")?;
                     }
                     ActiveStageOutput::PointerDefault => {