goto-ld: handle EFI binaries gracefully

Running objcopy on EFI binaries does not work, hence we need to give up on the
goto-cc sections in a graceful manner.

Author: tautschnig

src/goto-cc/hybrid_binary.cpp

@@ -16,27 +16,33 @@ Author: Michael Tautschnig, 2018
 
 #include <cstring>
 
+std::string objcopy_command(const std::string &compiler_or_linker)
+{
+  if(has_suffix(compiler_or_linker, "-ld"))
+  {
+    std::string objcopy_cmd = compiler_or_linker;
+    objcopy_cmd.erase(objcopy_cmd.size() - 2);
+    objcopy_cmd += "objcopy";
+
+    return objcopy_cmd;
+  }
+  else
+    return "objcopy";
+}
+
 int hybrid_binary(
   const std::string &compiler_or_linker,
   const std::string &goto_binary_file,
   const std::string &output_file,
-  message_handlert &message_handler)
+  message_handlert &message_handler,
+  bool linking_efi)
 {
   messaget message(message_handler);
 
-  int result;
+  int result = 0;
 
 #if defined(__linux__) || defined(__FreeBSD_kernel__)
-  std::string objcopy_cmd;
-
-  if(has_suffix(compiler_or_linker, "-ld"))
-  {
-    objcopy_cmd = compiler_or_linker;
-    objcopy_cmd.erase(objcopy_cmd.size() - 2);
-    objcopy_cmd += "objcopy";
-  }
-  else
-    objcopy_cmd = "objcopy";
+  const std::string objcopy_cmd = objcopy_command(compiler_or_linker);
 
   // merge output from gcc or ld with goto-binary using objcopy
 
@@ -52,7 +58,15 @@ int hybrid_binary(
       "--remove-section", "goto-cc",
       "--add-section", "goto-cc=" + goto_binary_file, output_file};
 
-    result = run(objcopy_argv[0], objcopy_argv, "", "");
+    const int add_section_result = run(objcopy_argv[0], objcopy_argv, "", "");
+    if(add_section_result != 0)
+    {
+      if(linking_efi)
+        message.warning() << "cannot merge EFI binaries: goto-cc section lost"
+                          << messaget::eom;
+      else
+        result = add_section_result;
+    }
   }
 
   // delete the goto binary

src/goto-cc/hybrid_binary.h

@@ -24,10 +24,18 @@ Date: May 2018
 /// \param goto_binary_file The file name of the goto binary
 /// \param output_file The name of the object file; the result is
 ///        stored here.
+/// \param linking_efi Set to true if linking x86 EFI binaries to relax error
+///        checking.
 int hybrid_binary(
   const std::string &compiler_or_linker,
   const std::string &goto_binary_file,
   const std::string &output_file,
-  message_handlert &);
+  message_handlert &,
+  bool linking_efi = false);
+
+/// Return the name of the objcopy tool matching the chosen compiler or linker
+/// command.
+/// \param compiler_or_linker Compiler or linker commmand
+std::string objcopy_command(const std::string &compiler_or_linker);
 
 #endif // CPROVER_GOTO_CC_HYBRID_BINARY_H

src/goto-cc/ld_mode.cpp

@@ -195,6 +195,38 @@ int ld_modet::ld_hybrid_binary(compilet &compiler)
     return result;
   }
 
+  const bool linking_efi = cmdline.get_value('m') == "i386pep";
+
+  #ifdef __linux__
+  if(linking_efi)
+  {
+    const std::string objcopy_cmd = objcopy_command(native_tool_name);
+
+    for(const auto &object_file : compiler.object_files)
+    {
+      debug() << "stripping goto-cc sections before building EFI binary" << eom;
+      // create a backup copy
+      const std::string bin_name = object_file + goto_binary_tmp_suffix;
+
+      std::ifstream in(object_file, std::ios::binary);
+      std::ofstream out(bin_name, std::ios::binary);
+      out << in.rdbuf();
+
+      // remove any existing goto-cc section
+      std::vector<std::string> objcopy_argv;
+
+      objcopy_argv.push_back(objcopy_cmd);
+      objcopy_argv.push_back("--remove-section=goto-cc");
+      objcopy_argv.push_back(object_file);
+
+      result = run(objcopy_argv[0], objcopy_argv, "", "");
+      if(result != 0)
+        debug() << "EFI binary preparation: removing goto-cc section failed"
+                << eom;
+    }
+  }
+  #endif
+
   result = run_ld();
 
   if(result == 0 && cmdline.isset('T'))
@@ -204,12 +236,32 @@ int ld_modet::ld_hybrid_binary(compilet &compiler)
     result = ls_merge.add_linker_script_definitions();
   }
 
+  #ifdef __linux__
+  if(linking_efi)
+  {
+    debug() << "arch set with " << compiler.object_files.size() << eom;
+    for(const auto &object_file : compiler.object_files)
+    {
+      debug() << "EFI binary preparation: restoring object files" << eom;
+      const std::string bin_name = object_file + goto_binary_tmp_suffix;
+      const int mv_result = rename(bin_name.c_str(), object_file.c_str());
+      if(mv_result != 0)
+        debug() << "Rename failed: " << std::strerror(errno) << eom;
+    }
+  }
+  #endif
+
   if(result == 0)
   {
     std::string native_linker = linker_name(cmdline, base_name);
 
-    result = hybrid_binary(
-      native_linker, goto_binary, output_file, get_message_handler());
+    result =
+      hybrid_binary(
+        native_linker,
+        goto_binary,
+        output_file,
+        get_message_handler(),
+        linking_efi);
   }
 
   return result;