[Rust] fixed RustGenerator::generateEncoderVarData() to cap slice len to primitive type size

Author: Michael Ward

build.gradle

@@ -679,8 +679,9 @@ tasks.register('generateRustTestCodecs', JavaExec) {
             'sbe-tool/src/test/resources/issue1028.xml',
             'sbe-tool/src/test/resources/issue1057.xml',
             'sbe-tool/src/test/resources/issue1066.xml',
-            'sbe-tool/src/test/resources/fixed-sized-primitive-array-types.xml',
+            'sbe-tool/src/test/resources/basic-variable-length-schema.xml',
             'sbe-tool/src/test/resources/example-bigendian-test-schema.xml',
+            'sbe-tool/src/test/resources/fixed-sized-primitive-array-types.xml',
             'sbe-tool/src/test/resources/nested-composite-name.xml',
     ]
 }

rust/Cargo.toml

@@ -2,7 +2,7 @@
 name = "sbe_rust_example"
 version = "0.1.0"
 authors = []
-edition = "2018"
+edition = "2021"
 publish = false
 
 [dependencies]
@@ -21,10 +21,11 @@ issue_1057 = { path = "../generated/rust/issue1057" }
 issue_1066 = { path = "../generated/rust/issue1066" }
 baseline_bigendian = { path = "../generated/rust/baseline-bigendian" }
 nested_composite_name = { path = "../generated/rust/nested-composite-name" }
+sbe_tests = { path = "../generated/rust/sbe_tests" }
 fixed_sized_primitive_array = { path = "../generated/rust/fixed_sized_primitive_array" }
 
 [dev-dependencies]
-criterion = "0.5"
+criterion = "0.7"
 
 [[bench]]
 name = "car_benchmark"

rust/tests/basic_variable_length_schema_test.rs

@@ -0,0 +1,43 @@
+use sbe_tests::{
+    message_header_codec::MessageHeaderDecoder,
+    test_message_1_codec::{
+        TestMessage1Decoder, SBE_BLOCK_LENGTH, SBE_SCHEMA_ID, SBE_SCHEMA_VERSION, SBE_TEMPLATE_ID,
+    },
+};
+use sbe_tests::{
+    WriteBuf,
+    {message_header_codec, test_message_1_codec::TestMessage1Encoder, Encoder, ReadBuf},
+};
+
+#[test]
+fn should_limit_var_data_length() {
+    // encode...
+    let mut buffer = vec![0u8; 1024];
+    let mut encoder = TestMessage1Encoder::default();
+    encoder = encoder.wrap(
+        WriteBuf::new(buffer.as_mut_slice()),
+        message_header_codec::ENCODED_LENGTH,
+    );
+    encoder = encoder.header(0).parent().unwrap();
+
+    let password: String = (0..1024).map(|_| 'x' as char).collect();
+    encoder.encrypted_new_password(password.as_bytes());
+    assert_eq!(263, encoder.get_limit());
+
+    // decode...
+    let buf = ReadBuf::new(buffer.as_slice());
+    let header = MessageHeaderDecoder::default().wrap(buf, 0);
+    assert_eq!(SBE_BLOCK_LENGTH, header.block_length());
+    assert_eq!(SBE_SCHEMA_VERSION, header.version());
+    assert_eq!(SBE_TEMPLATE_ID, header.template_id());
+    assert_eq!(SBE_SCHEMA_ID, header.schema_id());
+
+    let mut decoder = TestMessage1Decoder::default().header(header, 0);
+    let coord = decoder.encrypted_new_password_decoder();
+    let password = String::from_utf8_lossy(decoder.encrypted_new_password_slice(coord));
+    assert_eq!(254, password.len());
+    password
+        .as_bytes()
+        .iter()
+        .for_each(|x| assert_eq!(b'x', *x));
+}

sbe-tool/src/main/java/uk/co/real_logic/sbe/generation/rust/RustGenerator.java

@@ -356,14 +356,15 @@ static void generateEncoderVarData(
             indent(sb, level, "pub fn %s(&mut self, value: %s) {\n", propertyName, varDataType);
 
             indent(sb, level + 1, "let limit = self.get_limit();\n");
-            indent(sb, level + 1, "let data_length = value.len();\n");
+            indent(sb, level + 1, "let data_length = value.len().min((%s::MAX - 1) as usize);\n",
+                rustTypeName(lengthType));
             indent(sb, level + 1, "self.set_limit(limit + %d + data_length);\n", lengthType.size());
 
             indent(sb, level + 1,
                 "self.get_buf_mut().put_%s_at(limit, data_length as %1$s);\n",
                 rustTypeName(lengthType));
 
-            indent(sb, level + 1, "self.get_buf_mut().put_slice_at(limit + %d, value%s);\n",
+            indent(sb, level + 1, "self.get_buf_mut().put_slice_at(limit + %d, &value[0..data_length]%s);\n",
                 lengthType.size(),
                 toBytesFn);