Gold: Patch linker to fix LTO related bugs.

third_party/binutils/unlock-thin.patch

+commit 2cfbf2fece582c29df348104b28677c38a8301f4
+Author: Cary Coutant <ccoutant@google.com>
+Date:   Tue Feb 3 19:54:57 2015 -0800
+
+    Fix a file descriptor leak in gold.
+    
+    When an LTO linker plugin claims an external member of a thin archive, gold
+    does not properly unlock the file and make its file descriptor available for
+    reuse. This patch fixes the problem by modifying Archive::include_member to
+    unlock the object file via an RAII class instance, ensuring that it will be
+    unlocked no matter what path is taken through the function.
+    
+    gold/
+        PR gold/15660
+        * archive.cc (Thin_archive_object_unlocker): New class.
+        (Archive::include_member): Unlock external members of thin archives.
+        * testsuite/Makefile.am (plugin_test_1): Rename .syms files.
+        (plugin_test_2): Likewise.
+        (plugin_test_3): Likewise.
+        (plugin_test_4): Likewise.
+        (plugin_test_5): Likewise.
+        (plugin_test_6): Likewise.
+        (plugin_test_7): Likewise.
+        (plugin_test_8): Likewise.
+        (plugin_test_9): Likewise.
+        (plugin_test_10): Likewise.
+        (plugin_test_11): New test case.
+        * testsuite/Makefile.in: Regenerate.
+        * testsuite/plugin_test.c (claim_file_hook): Check for parallel .syms
+        file to decide whether to claim file.
+        (all_symbols_read_hook): Likewise.
+        * testsuite/plugin_test_1.sh: Adjust expected output.
+        * testsuite/plugin_test_2.sh: Likewise.
+        * testsuite/plugin_test_3.sh: Likewise.
+        * testsuite/plugin_test_6.sh: Likewise.
+        * testsuite/plugin_test_tls.sh: Likewise.
+        * testsuite/plugin_test_11.sh: New testcase.
+
+diff --git a/gold/archive.cc b/gold/archive.cc
+index 69107f5..6d25980 100644
+--- a/gold/archive.cc
++++ b/gold/archive.cc
+@@ -930,6 +930,32 @@ Archive::count_members()
+   return ret;
+ }
+ 
++// RAII class to ensure we unlock the object if it's a member of a
++// thin archive. We can't use Task_lock_obj in Archive::include_member
++// because the object file is already locked when it's opened by
++// get_elf_object_for_member.
++
++class Thin_archive_object_unlocker
++{
++ public:
++  Thin_archive_object_unlocker(const Task *task, Object* obj)
++    : task_(task), obj_(obj)
++  { }
++
++  ~Thin_archive_object_unlocker()
++  {
++    if (this->obj_->offset() == 0)
++      this->obj_->unlock(this->task_);
++  }
++
++ private:
++  Thin_archive_object_unlocker(const Thin_archive_object_unlocker&);
++  Thin_archive_object_unlocker& operator=(const Thin_archive_object_unlocker&);
++
++  const Task* task_;
++  Object* obj_;
++};
++
+ // Include an archive member in the link.  OFF is the file offset of
+ // the member header.  WHY is the reason we are including this member.
+ // Return true if we added the member or if we had an error, return
+@@ -978,6 +1004,10 @@ Archive::include_member(Symbol_table* symtab, Layout* layout,
+       return unconfigured ? false : true;
+     }
+ 
++  // If the object is an external member of a thin archive,
++  // unlock it when we're done here.
++  Thin_archive_object_unlocker unlocker(this->task_, obj);
++
+   if (mapfile != NULL)
+     mapfile->report_include_archive_member(obj->name(), sym, why);
+ 
+@@ -991,31 +1021,21 @@ Archive::include_member(Symbol_table* symtab, Layout* layout,
+ 
+   if (!input_objects->add_object(obj))
+     {
+-      // If this is an external member of a thin archive, unlock the
+-      // file.
+-      if (obj->offset() == 0)
+-       obj->unlock(this->task_);
+       delete obj;
++      return true;
+     }
+-  else
+-    {
+-      {
+-       if (layout->incremental_inputs() != NULL)
+-         layout->incremental_inputs()->report_object(obj, 0, this, NULL);
+-       Read_symbols_data sd;
+-       obj->read_symbols(&sd);
+-       obj->layout(symtab, layout, &sd);
+-       obj->add_symbols(symtab, &sd, layout);
+-      }
+-
+-      // If this is an external member of a thin archive, unlock the file
+-      // for the next task.
+-      if (obj->offset() == 0)
+-        obj->unlock(this->task_);
+ 
+-      this->included_member_ = true;
+-    }
++  if (layout->incremental_inputs() != NULL)
++    layout->incremental_inputs()->report_object(obj, 0, this, NULL);
++
++  {
++    Read_symbols_data sd;
++    obj->read_symbols(&sd);
++    obj->layout(symtab, layout, &sd);
++    obj->add_symbols(symtab, &sd, layout);
++  }
+ 
++  this->included_member_ = true;
+   return true;
+ }
+