coff: undefined symbols use IMAGE_SYM_CLASS_EXTERNAL

Author: philipc

src/read/coff/symbol.rs

@@ -169,7 +169,7 @@ pub(crate) fn parse_symbol<'data>(
     };
     let section = match section_number {
         pe::IMAGE_SYM_UNDEFINED => {
-            if symbol.storage_class == pe::IMAGE_SYM_CLASS_EXTERNAL {
+            if symbol.storage_class == pe::IMAGE_SYM_CLASS_EXTERNAL && value != 0 {
                 SymbolSection::Common
             } else {
                 SymbolSection::Undefined
@@ -189,9 +189,7 @@ pub(crate) fn parse_symbol<'data>(
     let weak = symbol.storage_class == pe::IMAGE_SYM_CLASS_WEAK_EXTERNAL;
     let scope = match symbol.storage_class {
         _ if section == SymbolSection::Undefined => SymbolScope::Unknown,
-        pe::IMAGE_SYM_CLASS_EXTERNAL
-        | pe::IMAGE_SYM_CLASS_EXTERNAL_DEF
-        | pe::IMAGE_SYM_CLASS_WEAK_EXTERNAL => {
+        pe::IMAGE_SYM_CLASS_EXTERNAL | pe::IMAGE_SYM_CLASS_WEAK_EXTERNAL => {
             // TODO: determine if symbol is exported
             SymbolScope::Linkage
         }

src/write/coff.rs

@@ -468,8 +468,9 @@ impl Object {
                                 symbol.name().unwrap_or("")
                             )));
                         }
-                        SymbolSection::Undefined => coff::IMAGE_SYM_CLASS_EXTERNAL_DEF,
-                        SymbolSection::Common => coff::IMAGE_SYM_CLASS_EXTERNAL,
+                        SymbolSection::Undefined | SymbolSection::Common => {
+                            coff::IMAGE_SYM_CLASS_EXTERNAL
+                        }
                         SymbolSection::Absolute | SymbolSection::Section(_) => {
                             match symbol.scope {
                                 // TODO: does this need aux symbol records too?

tests/round_trip/common.rs

@@ -33,6 +33,19 @@ fn coff_x86_64_common() {
     };
     object.add_common_symbol(symbol, 8, 8);
 
+    // Also check undefined symbols, which are very similar.
+    let symbol = write::Symbol {
+        name: b"v3".to_vec(),
+        value: 0,
+        size: 0,
+        kind: SymbolKind::Data,
+        scope: SymbolScope::Linkage,
+        weak: false,
+        section: write::SymbolSection::Undefined,
+        flags: SymbolFlags::None,
+    };
+    object.add_symbol(symbol);
+
     let bytes = object.write().unwrap();
 
     //std::fs::write(&"common.o", &bytes).unwrap();
@@ -65,6 +78,17 @@ fn coff_x86_64_common() {
     assert_eq!(symbol.address(), 0);
     assert_eq!(symbol.size(), 8);
 
+    let (_, symbol) = symbols.next().unwrap();
+    println!("{:?}", symbol);
+    assert_eq!(symbol.name(), Some("v3"));
+    assert_eq!(symbol.kind(), SymbolKind::Data);
+    assert_eq!(symbol.section(), read::SymbolSection::Undefined);
+    assert_eq!(symbol.scope(), SymbolScope::Unknown);
+    assert_eq!(symbol.is_weak(), false);
+    assert_eq!(symbol.is_undefined(), true);
+    assert_eq!(symbol.address(), 0);
+    assert_eq!(symbol.size(), 0);
+
     let symbol = symbols.next();
     assert!(symbol.is_none(), format!("unexpected symbol {:?}", symbol));
 }