wasm file loader and header validation

test/build_wasm.sh

@@ -0,0 +1,20 @@
+#!/bin/sh
+# Compile all .wat files to .wasm
+# Run from the test/ directory
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+WAT_DIR="$SCRIPT_DIR/wat"
+WASM_DIR="$SCRIPT_DIR/wasm"
+
+mkdir -p "$WASM_DIR"
+
+for f in "$WAT_DIR"/*.wat; do
+    base=$(basename "$f" .wat)
+    wat2wasm "$f" -o "$WASM_DIR/$base.wasm"
+    echo "  $base.wat -> $base.wasm"
+done
+
+# edge cases
+/usr/bin/printf '\x00asm\x02\x00\x00\x00' > "$WASM_DIR/badver.wasm"
+/usr/bin/printf '\x00bad\x01\x00\x00\x00' > "$WASM_DIR/badmagic.wasm"
+

test/run_tests.sh

@@ -0,0 +1,34 @@
+#!/bin/sh
+# Run from the repo root
+
+WASM=./src/wasm
+PASS=0
+FAIL=0
+TESTS=0
+
+check() {
+    TESTS=$((TESTS + 1))
+    desc="$1"; shift
+    expected="$1"; shift
+    output=$("$@" 2>&1)
+    if echo "$output" | grep -q "$expected"; then
+        PASS=$((PASS + 1))
+        echo "  OK   $desc"
+    else
+        FAIL=$((FAIL + 1))
+        echo "  FAIL $desc"
+        echo "       expected: $expected"
+        echo "       got: $output"
+    fi
+}
+
+echo "=== wasm runtime tests ==="
+
+check "no arguments"    "Usage:"               $WASM
+check "valid wasm"      "Valid wasm file"       $WASM test/wasm/valid.wasm
+check "bad magic"       "invalid wasm magic"    $WASM test/wasm/badmagic.wasm
+check "bad version"     "unsupported wasm"      $WASM test/wasm/badver.wasm
+
+echo ""
+echo "Results: $PASS/$TESTS passed, $FAIL failed"
+[ "$FAIL" -eq 0 ] && exit 0 || exit 1

test/wat/valid.wat

@@ -0,0 +1,5 @@
+(module
+  (func (export "getSomething") (result i32)
+    i32.const 42
+  )
+)