fix: VarChar handling raw string, VarChar Inz silent drop

rpgrt/src/lib.rs

@@ -11,6 +11,8 @@
 //! | `rpg_dsply_cstr`    | `(ptr: *const c_char)`                 | Display a null-terminated C string   |
 //! | `rpg_dsply_i64`     | `(n: i64)`                             | Display a signed 64-bit integer      |
 //! | `rpg_dsply_f64`     | `(f: f64)`                             | Display a double-precision float     |
+//! | `rpg_dsply_read`    | `(prompt: *const c_char, response: *mut i64)` | Display null-term prompt & read i64 |
+//! | `rpg_dsply_read_len`| `(ptr: *const u8, len: i64, response: *mut i64)` | Display length-delimited prompt & read i64 |
 //! | `rpg_halt`          | `(code: i32)`                          | Abnormal program termination         |
 //! | `rpg_char_i64`      | `(n: i64) -> *const c_char`            | Format integer as null-term C string |
 //! | `rpg_concat`        | `(a: *const c_char, b: *const c_char) -> *const c_char` | Concatenate two C strings |
@@ -209,6 +211,59 @@ pub unsafe extern "C" fn rpg_dsply_read(
     }
 }
 
+// ─────────────────────────────────────────────────────────────────────────────
+// rpg_dsply_read_len — display a length-delimited prompt and read a response
+// ─────────────────────────────────────────────────────────────────────────────
+
+/// Three-operand DSPLY where the prompt is a fixed-length (or VarChar) field
+/// passed as `(ptr, len)` rather than a null-terminated C string.
+///
+/// This is called when the prompt operand is a `Char` or `VarChar` variable —
+/// those are stored as raw byte buffers with no null terminator, so
+/// `rpg_dsply_read` (which calls `CStr::from_ptr`) cannot be used safely.
+///
+/// Trailing ASCII spaces are stripped from the prompt before display, matching
+/// the behaviour of `rpg_dsply`.
+///
+/// # Safety
+///
+/// * `ptr` must be valid for at least `len` bytes (or be null).
+/// * `response` must be a valid, writable `i64` pointer.
+#[no_mangle]
+pub unsafe extern "C" fn rpg_dsply_read_len(
+    ptr: *const u8,
+    len: i64,
+    response: *mut i64,
+) {
+    use std::io::BufRead;
+
+    // Build the prompt string the same way rpg_dsply does.
+    let bytes = if ptr.is_null() || len <= 0 {
+        b"" as &[u8]
+    } else {
+        unsafe { slice::from_raw_parts(ptr, len as usize) }
+    };
+    let trimmed = rtrim_spaces(bytes);
+    let text = String::from_utf8_lossy(trimmed);
+
+    {
+        let stdout = io::stdout();
+        let mut out = stdout.lock();
+        let _ = writeln!(out, "DSPLY  {}", text);
+        let _ = out.flush();
+    }
+
+    // Read one line from stdin and parse it as i64.
+    let stdin = io::stdin();
+    let mut line = String::new();
+    if stdin.lock().read_line(&mut line).is_ok() {
+        let trimmed_line = line.trim();
+        if let Ok(n) = trimmed_line.parse::<i64>() {
+            unsafe { *response = n; }
+        }
+    }
+}
+
 // ─────────────────────────────────────────────────────────────────────────────
 // rpg_halt — abnormal termination
 // ─────────────────────────────────────────────────────────────────────────────

samples/3np1.rpg.stdout

@@ -1,8 +1,8 @@
-DSPLY
+DSPLY  Enter a positive integer (or 0 to exit):
 DSPLY  Sequence for 8:
 DSPLY  4
 DSPLY  2
 DSPLY  1
 DSPLY  Reached 1 in 3 iterations.
-DSPLY
-DSPLY
+DSPLY  
+DSPLY  Enter a positive integer (or 0 to exit):

src/codegen.rs

@@ -341,13 +341,22 @@ impl<'ctx> Codegen<'ctx> {
         self.module.add_function("rpg_concat", concat_ty, None);
 
         // void rpg_dsply_read(const char *prompt, i64 *response)
-        // Three-operand DSPLY: display prompt and read an i64 from stdin.
+        // Three-operand DSPLY: display null-terminated prompt and read an i64 from stdin.
         let i64_ptr = self.context.ptr_type(AddressSpace::default());
         let dsply_read_ty = void_t.fn_type(
             &[i8_ptr.into(), i64_ptr.into()],
             false,
         );
         self.module.add_function("rpg_dsply_read", dsply_read_ty, None);
+
+        // void rpg_dsply_read_len(const u8 *ptr, i64 len, i64 *response)
+        // Three-operand DSPLY where the prompt is a length-delimited byte buffer
+        // (Char / VarChar variable) rather than a null-terminated C string.
+        let dsply_read_len_ty = void_t.fn_type(
+            &[i8_ptr.into(), i64_t.into(), i64_ptr.into()],
+            false,
+        );
+        self.module.add_function("rpg_dsply_read_len", dsply_read_len_ty, None);
     }
 
     // ── Global declarations ─────────────────────────────────────────────────
@@ -745,8 +754,10 @@ impl<'ctx> Codegen<'ctx> {
         state: &mut FnState<'ctx>,
     ) -> Result<(), CodegenError> {
         match ty {
-            TypeSpec::Char(size_expr) => {
-                // Copy a string literal into the char buffer (space-padded).
+            TypeSpec::Char(size_expr) | TypeSpec::VarChar(size_expr) => {
+                // Copy a string literal into the char/varchar buffer (space-padded to
+                // the declared length so that rpg_dsply and rpg_dsply_read_len get
+                // clean data with no uninitialized bytes past the content).
                 if let Expression::Literal(Literal::String(s)) = expr {
                     let field_len = const_int_from_expr(size_expr).unwrap_or(s.len() as u64) as usize;
                     // Build a space-padded string of exactly `field_len` bytes.
@@ -1005,30 +1016,6 @@ impl<'ctx> Codegen<'ctx> {
         // When a response variable is present we display the prompt and then
         // read an integer from stdin into the response variable.
         if let Some(resp_name) = &d.response {
-            // Coerce the prompt expression to a C string pointer.
-            let prompt_ptr = match &d.expr {
-                Expression::Variable(qname) => {
-                    let name = qname.leaf();
-                    if let Some((ptr, _)) = self.resolve_var(name, state) {
-                        ptr.into()
-                    } else {
-                        self.intern_string("").into()
-                    }
-                }
-                Expression::Literal(Literal::String(s)) => {
-                    self.intern_string(s).into()
-                }
-                other => {
-                    if let Ok(BasicValueEnum::PointerValue(ptr)) =
-                        self.gen_expression(other, state)
-                    {
-                        ptr.into()
-                    } else {
-                        self.intern_string("").into()
-                    }
-                }
-            };
-
             // Resolve the response variable; allocate a fresh i64 slot in the
             // function entry block if not already present.  Using
             // alloca_i64_in_entry ensures the slot is created once regardless
@@ -1055,14 +1042,83 @@ impl<'ctx> Codegen<'ctx> {
                     p
                 };
 
-            if let Some(read_fn) = self.module.get_function("rpg_dsply_read") {
-                self.builder
-                    .build_call(read_fn, &[prompt_ptr, resp_ptr.into()], "dsply_read")
-                    .ok();
+            // Choose the right runtime call based on the prompt operand type:
+            //
+            //   • Char/VarChar variable  → rpg_dsply_read_len(ptr, len, resp)
+            //     The storage is a raw byte buffer with no null terminator, so
+            //     we pass the pointer and byte length directly.
+            //
+            //   • String literal or other expression → rpg_dsply_read(cstr, resp)
+            //     intern_string always null-terminates its result.
+            match &d.expr {
+                Expression::Variable(qname) => {
+                    let name = qname.leaf();
+                    if let Some((ptr, ty)) = self.resolve_var(name, state) {
+                        match &ty {
+                            TypeSpec::Char(_) | TypeSpec::VarChar(_) => {
+                                // Length-delimited path.
+                                let len = ty.byte_size().unwrap_or(0);
+                                let len_val = self.context.i64_type().const_int(len, false);
+                                if let Some(read_fn) = self.module.get_function("rpg_dsply_read_len") {
+                                    self.builder
+                                        .build_call(
+                                            read_fn,
+                                            &[ptr.into(), len_val.into(), resp_ptr.into()],
+                                            "dsply_read_len",
+                                        )
+                                        .ok();
+                                }
+                            }
+                            _ => {
+                                // Treat as a null-terminated C string (e.g. a
+                                // pointer returned by %Char / rpg_char_i64).
+                                if let Some(read_fn) = self.module.get_function("rpg_dsply_read") {
+                                    self.builder
+                                        .build_call(read_fn, &[ptr.into(), resp_ptr.into()], "dsply_read")
+                                        .ok();
+                                }
+                            }
+                        }
+                    } else {
+                        // Unknown variable — display an empty prompt and still read.
+                        let empty = self.intern_string("");
+                        if let Some(read_fn) = self.module.get_function("rpg_dsply_read") {
+                            self.builder
+                                .build_call(read_fn, &[empty.into(), resp_ptr.into()], "dsply_read")
+                                .ok();
+                        }
+                    }
+                }
+                Expression::Literal(Literal::String(s)) => {
+                    let s = s.clone();
+                    let cstr = self.intern_string(&s);
+                    if let Some(read_fn) = self.module.get_function("rpg_dsply_read") {
+                        self.builder
+                            .build_call(read_fn, &[cstr.into(), resp_ptr.into()], "dsply_read")
+                            .ok();
+                    }
+                }
+                other => {
+                    // Evaluate the expression; if it yields a pointer (e.g. the
+                    // result of a %Char() / rpg_concat call) use the cstr path.
+                    let other = other.clone();
+                    let prompt_ptr = if let Ok(BasicValueEnum::PointerValue(ptr)) =
+                        self.gen_expression(&other, state)
+                    {
+                        ptr
+                    } else {
+                        self.intern_string("")
+                    };
+                    if let Some(read_fn) = self.module.get_function("rpg_dsply_read") {
+                        self.builder
+                            .build_call(read_fn, &[prompt_ptr.into(), resp_ptr.into()], "dsply_read")
+                            .ok();
+                    }
+                }
             }
+
             return Ok(());
         }
-
         // ── One-operand form: DSPLY expr ──────────────────────────────────
         match &d.expr {
             Expression::Variable(qname) => {