From 481a5c6cb2347317e19e9787ed01e6596bcaf6a5 Mon Sep 17 00:00:00 2001
From: Gabriel Ionita <d9rect@pm.me>
Date: Sat, 25 Oct 2025 13:25:00 +0100
Subject: [PATCH] implement get_var_size to retrieve variable byte size from
 DWARF

---
 src/symbol.cpp | 75 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)

diff --git a/src/symbol.cpp b/src/symbol.cpp
index d797925..d5af909 100644
--- a/src/symbol.cpp
+++ b/src/symbol.cpp
@@ -149,6 +149,81 @@ Dwarf_Addr Symbol::get_global_var_addr(Dwarf_Debug dbg, Dwarf_Die die) {
   return addr;
 }
 
+size_t Symbol::get_var_size(Dwarf_Debug dbg, Dwarf_Die die) {
+  Dwarf_Error err;
+  Dwarf_Attribute type_attr;
+  Dwarf_Off type_offset;
+  Dwarf_Die type_die;
+  Dwarf_Half tag;
+
+  // Get the type attribute
+  if (dwarf_attr(die, DW_AT_type, &type_attr, &err) != DW_DLV_OK)
+    return 0;
+
+  // Get the type offset
+  if (dwarf_global_formref(type_attr, &type_offset, &err) != DW_DLV_OK) {
+    dwarf_dealloc(dbg, type_attr, DW_DLA_ATTR);
+    return 0;
+  }
+
+  dwarf_dealloc(dbg, type_attr, DW_DLA_ATTR);
+
+  // Get the type DIE
+  if (dwarf_offdie_b(dbg, type_offset, true, &type_die, &err) != DW_DLV_OK)
+    return 0;
+
+  // Get the tag of the type DIE
+  if (dwarf_tag(type_die, &tag, &err) != DW_DLV_OK) {
+    dwarf_dealloc(dbg, type_die, DW_DLA_DIE);
+    return 0;
+  }
+
+  // Skip through const/volatile qualifiers
+  while (tag == DW_TAG_const_type || tag == DW_TAG_volatile_type) {
+    Dwarf_Attribute inner_type_attr;
+    Dwarf_Off inner_type_offset;
+    Dwarf_Die inner_type_die;
+
+    if (dwarf_attr(type_die, DW_AT_type, &inner_type_attr, &err) != DW_DLV_OK) {
+      dwarf_dealloc(dbg, type_die, DW_DLA_DIE);
+      return 0;
+    }
+
+    if (dwarf_global_formref(inner_type_attr, &inner_type_offset, &err) != DW_DLV_OK) {
+      dwarf_dealloc(dbg, inner_type_attr, DW_DLA_ATTR);
+      dwarf_dealloc(dbg, type_die, DW_DLA_DIE);
+      return 0;
+    }
+
+    dwarf_dealloc(dbg, inner_type_attr, DW_DLA_ATTR);
+
+    if (dwarf_offdie_b(dbg, inner_type_offset, true, &inner_type_die, &err) != DW_DLV_OK) {
+      dwarf_dealloc(dbg, type_die, DW_DLA_DIE);
+      return 0;
+    }
+
+    dwarf_dealloc(dbg, type_die, DW_DLA_DIE);
+    type_die = inner_type_die;
+
+    if (dwarf_tag(type_die, &tag, &err) != DW_DLV_OK) {
+      dwarf_dealloc(dbg, type_die, DW_DLA_DIE);
+      return 0;
+    }
+  }
+
+  // Get the byte size
+  Dwarf_Attribute size_attr;
+  Dwarf_Unsigned byte_size = 0;
+
+  if (dwarf_attr(type_die, DW_AT_byte_size, &size_attr, &err) == DW_DLV_OK) {
+    dwarf_formudata(size_attr, &byte_size, &err);
+    dwarf_dealloc(dbg, size_attr, DW_DLA_ATTR);
+  }
+
+  dwarf_dealloc(dbg, type_die, DW_DLA_DIE);
+  return byte_size;
+}
+
 void Symbol::list_global_integer_vars(Dwarf_Debug dbg) {
   Dwarf_Error err;
   Dwarf_Unsigned cu_hdr_len, abbr_offset, next_cu_hdr;