nasm: warn on labels that point out of bounds

Signed-off-by: Miquel Sabaté Solà <mssola@mssola.com>

5 files changed, 39 insertions, 2 deletions

diff --git a/lib/xixanta/src/assembler.rs b/lib/xixanta/src/assembler.rs
index afd8429..6006234 100644
--- a/lib/xixanta/src/assembler.rs
+++ b/lib/xixanta/src/assembler.rs
@@ -918,7 +918,7 @@ impl<'a> Assembler<'a> {
                 negative: false,
                 safe: false,
             },
-            node: None,
+            node: Some(node.clone()),
             mapping: self.current_mapping,
             segment: self.current_segment,
             object_type,
@@ -1459,8 +1459,25 @@ impl<'a> Assembler<'a> {
                         // badly formatted addresses. This will not happen at
                         // this point.
                         let resolved = self.context.resolve_label(&self.mappings, bundle).unwrap();
-
                         let val = resolved.bundle.value() as usize;
+
+                        // If this is an address, is it pointing out of bounds?
+                        if matches!(bundle.object_type, ObjectType::Address) {
+                            let mapping = &self.mappings[resolved.mapping];
+                            let filled_mapping = mapping.start as usize + mapping.offset;
+                            if val >= filled_mapping {
+                                self.warnings.push(Error {
+                                    line: resolved.node.as_ref().unwrap().value.line,
+                                    message: format!("label '{full_name}' is pointing to out of bounds"),
+                                    source: self.sources[0].clone(),
+                                    expanded_from: self.macro_context.clone(),
+                                    global: false,
+                                });
+                            }
+                        }
+
+                        // If not, then create a range out of this object and
+                        // push the address.
                         let end = match self.address_ends.get(&full_name) {
                             Some(v) => v,
                             None => &val,
diff --git a/scripts/test-e2e.sh b/scripts/test-e2e.sh
index 4df7128..4b9af90 100755
--- a/scripts/test-e2e.sh
+++ b/scripts/test-e2e.sh
@@ -147,6 +147,13 @@ exit_code=$((exit_code + $?))
 diff tests/out/global-labels.nes tests/expected/global-labels.nes
 exit_code=$((exit_code + $?))
 
+echo "test: custom => out.nes"
+./target/debug/nasm -c empty -Werror --asan -o tests/out/out.nes tests/out.s 2>tests/out/out.txt
+diff tests/out/out.txt tests/expected/out.txt
+exit_code=$((exit_code + $?))
+diff tests/out/out.nes tests/expected/out.nes
+exit_code=$((exit_code + $?))
+
 ##
 # code.nes
 
diff --git a/tests/expected/out.nes b/tests/expected/out.nes
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/tests/expected/out.nes
diff --git a/tests/expected/out.txt b/tests/expected/out.txt
new file mode 100644
index 0000000..7f7a94c
--- /dev/null
+++ b/tests/expected/out.txt
@@ -0,0 +1 @@
+error: label 'label' is pointing to out of bounds (out.s: line 12)
diff --git a/tests/out.s b/tests/out.s
new file mode 100644
index 0000000..d40ec42
--- /dev/null
+++ b/tests/out.s
@@ -0,0 +1,12 @@
+.segment "HEADER"
+    .byte 'N', 'E', 'S', $1A
+    .byte $02, $01
+    .byte $00
+    .byte $00
+
+.segment "CODE"
+;; asan:stack full
+
+jmp label
+nop
+label: