Ignore hidden symbols from shared objects

Issue #604

Author: davidlattimore

libwild/src/elf.rs

@@ -513,3 +513,7 @@ pub(crate) fn slice_from_all_bytes_mut<T: object::Pod>(data: &mut [u8]) -> &mut
         .unwrap()
         .0
 }
+
+pub(crate) fn is_hidden_symbol(symbol: &crate::elf::Symbol) -> bool {
+    symbol.st_visibility() == object::elf::STV_HIDDEN
+}

libwild/src/resolution.rs

@@ -883,8 +883,12 @@ fn resolve_symbol<'data>(
     is_from_shared_object: bool,
 ) -> Result {
     // Don't try to resolve symbols that are already defined, e.g. locals and globals that we
-    // define. Also don't try to resolve symbol zero - the undefined symbol.
-    if !definition_out.is_undefined() || local_symbol_index.0 == 0 {
+    // define. Also don't try to resolve symbol zero - the undefined symbol. Hidden symbols exported
+    // from shared objects don't make sense, so we skip resolving them as well.
+    if !definition_out.is_undefined()
+        || local_symbol_index.0 == 0
+        || (is_from_shared_object && crate::elf::is_hidden_symbol(local_symbol))
+    {
         return Ok(());
     }
 

libwild/src/symbol_db.rs

@@ -932,10 +932,12 @@ trait SymbolLoader<'data> {
         for symbol in self.object().symbols.iter() {
             let symbol_id = symbols_out.next;
             let mut value_flags = self.compute_value_flags(symbol);
-            if symbol.is_undefined(e) {
+
+            if symbol.is_undefined(e) || self.should_ignore_symbol(symbol) {
                 symbols_out.set_next(value_flags, SymbolId::undefined(), file_id);
                 continue;
             }
+
             let resolution = symbol_id;
 
             let local_index = symbol_id.offset_from(base_symbol_id);
@@ -983,6 +985,11 @@ trait SymbolLoader<'data> {
         false
     }
 
+    /// Returns whether the supplied symbol should be ignore.
+    fn should_ignore_symbol(&self, _symbol: &crate::elf::Symbol) -> bool {
+        false
+    }
+
     fn get_symbol_name_and_version(
         &self,
         symbol: &crate::elf::Symbol,
@@ -1141,6 +1148,11 @@ impl<'data> SymbolLoader<'data> for DynamicObjectSymbolLoader<'_, 'data> {
     fn object(&self) -> &crate::elf::File<'data> {
         self.object
     }
+
+    fn should_ignore_symbol(&self, symbol: &crate::elf::Symbol) -> bool {
+        // Shared objects shouldn't export hidden symbols. If for some reason they do, ignore them.
+        crate::elf::is_hidden_symbol(symbol)
+    }
 }
 
 #[derive(Clone, Copy)]