gdb: refactor objfile::find_and_add_separate_symbol_file

This is purely a refactoring commit.

This commit splits objfile::find_and_add_separate_symbol_file into
some separate helper functions.  My hope is that the steps for looking
up separate debug information are now clearer.

In a later commit I'm going to extend
objfile::find_and_add_separate_symbol_file, with some additional
logic, so starting with a simpler function will make the following
changes easier.

When reading objfile::find_and_add_separate_symbol_file after this
commit, you might be tempted to think that removing the `has_dwarf`
local variable would be a good additional cleanup.  After the next
commit though it makes more sense to retain this local, so I've left
this in place for now.

There should be no user visible changes after this commit.

Approved-By: Tom Tromey <[email protected]>

gdb/symfile-debug.c

@@ -560,68 +560,109 @@ objfile::require_partial_symbols (bool verbose)
     }
 }
 
+/* Call LOOKUP_FUNC to find the filename of a file containing the separate
+   debug information matching OBJFILE.  If LOOKUP_FUNC does return a
+   filename then open this file and return a std::pair containing the
+   gdb_bfd_ref_ptr of the open file and the filename returned by
+   LOOKUP_FUNC, otherwise this function returns an empty pair; the first
+   item will be nullptr, and the second will be an empty string.
+
+   Any warnings generated by this function, or by calling LOOKUP_FUNC are
+   placed into WARNINGS, these warnings are only displayed to the user if
+   GDB is unable to find the separate debug information via any route.  */
+static std::pair<gdb_bfd_ref_ptr, std::string>
+simple_find_and_open_separate_symbol_file
+  (struct objfile *objfile,
+   std::string (*lookup_func) (struct objfile *, deferred_warnings *),
+   deferred_warnings *warnings)
+{
+  std::string filename = lookup_func (objfile, warnings);
+
+  if (!filename.empty ())
+    {
+      gdb_bfd_ref_ptr symfile_bfd
+	= symfile_bfd_open_no_error (filename.c_str ());
+      if (symfile_bfd != nullptr)
+	return { symfile_bfd, filename };
+    }
+
+  return {};
+}
+
+/* Lookup separate debug information for OBJFILE via debuginfod.  If
+   successful the debug information will be have been downloaded into the
+   debuginfod cache and this function will return a std::pair containing a
+   gdb_bfd_ref_ptr of the open debug information file and the filename for
+   the file within the debuginfod cache.  If no debug information could be
+   found then this function returns an empty pair; the first item will be
+   nullptr, and the second will be an empty string.  */
+
+static std::pair<gdb_bfd_ref_ptr, std::string>
+debuginfod_find_and_open_separate_symbol_file (struct objfile * objfile)
+{
+  const struct bfd_build_id *build_id
+    = build_id_bfd_get (objfile->obfd.get ());
+  const char *filename = bfd_get_filename (objfile->obfd.get ());
+
+  if (build_id != nullptr)
+    {
+      gdb::unique_xmalloc_ptr<char> symfile_path;
+      scoped_fd fd (debuginfod_debuginfo_query (build_id->data, build_id->size,
+						filename, &symfile_path));
+
+      if (fd.get () >= 0)
+	{
+	  /* File successfully retrieved from server.  */
+	  gdb_bfd_ref_ptr debug_bfd
+	    (symfile_bfd_open_no_error (symfile_path.get ()));
+
+	  if (debug_bfd != nullptr
+	      && build_id_verify (debug_bfd.get (),
+				  build_id->size, build_id->data))
+	    return { debug_bfd, std::string (symfile_path.get ()) };
+	}
+    }
+
+  return {};
+}
+
 /* See objfiles.h.  */
 
 bool
 objfile::find_and_add_separate_symbol_file (symfile_add_flags symfile_flags)
 {
-  bool has_dwarf2 = true;
+  bool has_dwarf = false;
 
   deferred_warnings warnings;
 
-  std::string debugfile
-    = find_separate_debug_file_by_buildid (this, &warnings);
-
-  if (debugfile.empty ())
-    debugfile = find_separate_debug_file_by_debuglink (this, &warnings);
+  gdb_bfd_ref_ptr debug_bfd;
+  std::string filename;
 
-  if (!debugfile.empty ())
-    {
-      gdb_bfd_ref_ptr debug_bfd
-	(symfile_bfd_open_no_error (debugfile.c_str ()));
+  std::tie (debug_bfd, filename) = simple_find_and_open_separate_symbol_file
+    (this, find_separate_debug_file_by_buildid, &warnings);
 
-      if (debug_bfd != nullptr)
-	symbol_file_add_separate (debug_bfd, debugfile.c_str (),
-				  symfile_flags, this);
-    }
-  else
-    {
-      has_dwarf2 = false;
-      const struct bfd_build_id *build_id
-	= build_id_bfd_get (this->obfd.get ());
-      const char *filename = bfd_get_filename (this->obfd.get ());
-
-      if (build_id != nullptr)
-	{
-	  gdb::unique_xmalloc_ptr<char> symfile_path;
-	  scoped_fd fd (debuginfod_debuginfo_query (build_id->data,
-						    build_id->size,
-						    filename,
-						    &symfile_path));
+  if (debug_bfd == nullptr)
+    std::tie (debug_bfd, filename)
+      = simple_find_and_open_separate_symbol_file
+	  (this, find_separate_debug_file_by_debuglink, &warnings);
 
-	  if (fd.get () >= 0)
-	    {
-	      /* File successfully retrieved from server.  */
-	      gdb_bfd_ref_ptr debug_bfd
-		(symfile_bfd_open_no_error (symfile_path.get ()));
+  if (debug_bfd == nullptr)
+    std::tie (debug_bfd, filename)
+      = debuginfod_find_and_open_separate_symbol_file (this);
 
-	      if (debug_bfd != nullptr
-		  && build_id_verify (debug_bfd.get (), build_id->size,
-				      build_id->data))
-		{
-		  symbol_file_add_separate (debug_bfd, symfile_path.get (),
-					    symfile_flags, this);
-		  has_dwarf2 = true;
-		}
-	    }
-	}
+  if (debug_bfd != nullptr)
+    {
+      symbol_file_add_separate (debug_bfd, filename.c_str (), symfile_flags,
+				this);
+      has_dwarf = true;
     }
-  /* If all the methods to collect the debuginfo failed, print the
-     warnings, this is a no-op if there are no warnings.  */
-  if (debugfile.empty () && !has_dwarf2)
+
+  /* If we still have not got a separate debug symbol file, then
+     emit any warnings we've collected so far.  */
+  if (!has_dwarf)
     warnings.emit ();
 
-  return has_dwarf2;
+  return has_dwarf;
 }