PNaCl Dynamic Linking: Using unordered_set to disallow duplicate modules.

src/untrusted/pll_loader/pll_loader.h

 // Copyright 2016 The Native Client Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NATIVE_CLIENT_SRC_UNTRUSTED_PLL_LOADER_PLL_LOADER_H_
 #define NATIVE_CLIENT_SRC_UNTRUSTED_PLL_LOADER_PLL_LOADER_H_ 1
 
+#include <string>
+#include <unordered_set>
 #include <vector>
 
 #include "native_client/src/untrusted/pll_loader/pll_root.h"
 
 // This helper class wraps the PLLRoot data structure and provides methods
 // for accessing parts of PLLRoot.
 class PLLModule {
  public:
   explicit PLLModule(const PLLRoot *root) : root_(root) {}
 
@@ skipping 17 matching lines @@
   void *GetExportedSym(const char *name);
   void *InstantiateTLSBlock();
 
  private:
   const PLLRoot *root_;
 };
 
 // ModuleSet represents a set of loaded PLLs.
 class ModuleSet {
  public:
-  // Load a PLL and add it to the set.
+  // Load a PLL by filename. Does not add the filename to a known set of loaded
+  // modules, and will not de-duplicate loading modules.
   void AddByFilename(const char *filename);
 
+  // Change the search path used by the linker when looking for PLLs by soname.
+  void SetSonameSearchPath(const std::vector<std::string> &dir_list);
+
+  // Load a PLL by soname and add the soname to the set of loaded modules.
+  void AddBySoname(const char *soname);
+
   // Looks up a symbol in the set of modules.  This does a linear search of
   // the modules, in the order that they were added using AddByFilename().
   void *GetSym(const char *name);
 
   // Applies relocations to the modules, resolving references between them.
   void ResolveRefs();
 
  private:
+  // The search path used to look for "sonames".
+  std::vector<std::string> search_path_;
+  // An unordered set of "sonames" (to see if a module has been loaded).
+  std::unordered_set<std::string> sonames_;
   std::vector<PLLModule> modules_;
 };
 
 #endif