gdb: change 'maint info section' to use command options

The 'maintenance info sections' command currently takes a list of
filters on the command line.  It can also accept the magic string
'ALLOBJ' which acts more like a command line flag, telling the command
to print information about all objfiles.

The manual has this to say about the options and filters:

  ... In addition, 'maint info sections' provides the following
  command options (which may be arbitrarily combined): ...

Implying (to me at least) that I can do this:

  (gdb) maint info sections ALLOBJ READONLY

to list all the read-only sections from all currently loaded object
files.

Unfortunately, this doesn't work.  The READONLY filter will work, but
ALLOBJ will not be detected correctly.

It would be fairly simple to fix the ALLOBJ detection.  However, I
dislike this mixing of command options (ALLOBJ) with command data (the
filters, e.g. READONLY, etc).

As this is a maintenance command, so not really intended for end
users, I think we can be a little more aggressive in "fixing" the
option parsing.  So that's what I do in this commit.

The ALLOBJ mechanism is replaced with a real command
option (-all-objects).  The rest of the command operates just as
before.  The example above would now become:

  (gdb) maint info sections -all-objects READONLY

The manual has been updated, and I added a NEWS entry to document the
change.

gdb/ChangeLog:

	* NEWS: Mention changes to 'maint info sections'.
	* maint.c (match_substring): Return a bool, fix whitespace issue.
	(struct single_bfd_flag_info): New struct.
	(bfd_flag_info): New static global.
	(match_bfd_flags): Return a bool, use bfd_flag_info.
	(print_bfd_flags): Use bfd_flag_info.
	(maint_print_section_info): Delete trailing whitespace.
	(struct maint_info_sections_opts): New struct.
	(maint_info_sections_option_defs): New static global.
	(maint_info_sections_completer): New function.
	(maintenance_info_sections): Use option parsing mechanism.
	(_initialize_maint_cmds): Register command completer.

gdb/doc/ChangeLog:

	* gdb.texinfo (Files): Update documentation for 'maint info
	sections'.

gdb/testsuite/ChangeLog:

	* gdb.base/maint-info-sections.exp: Update expected output, and
	add additional tests. Again.

1 files changed, 138 insertions, 90 deletions

diff --git a/gdb/maint.c b/gdb/maint.c
index 0dda11b..707d156 100644
--- a/gdb/maint.c
+++ b/gdb/maint.c
@@ -131,10 +131,10 @@ maintenance_space_display (const char *args, int from_tty)
 
 /* Mini tokenizing lexer for 'maint info sections' command.  */
 
-static int
+static bool
 match_substring (const char *string, const char *substr)
 {
-  int substr_len = strlen(substr);
+  int substr_len = strlen (substr);
   const char *tok;
 
   while ((tok = strstr (string, substr)) != NULL)
@@ -150,90 +150,82 @@ match_substring (const char *string, const char *substr)
 	    || tok[substr_len] == '\0')
 	{
 	  /* Token is delimited at the rear.  Got a whole-word match.  */
-	  return 1;
+	  return true;
 	}
       }
       /* Token didn't match as a whole word.  Advance and try again.  */
       string = tok + 1;
     }
-  return 0;
+  return false;
 }
 
-static int 
+/* Structure holding information about a single bfd section flag.  This is
+   used by the "maintenance info sections" command to print the sections,
+   and for filtering which sections are printed.  */
+
+struct single_bfd_flag_info
+{
+  /* The name of the section.  This is what is printed for the flag, and
+     what the user enter in order to filter by flag.  */
+  const char *name;
+
+  /* The bfd defined SEC_* flagword value for this flag.  */
+  flagword value;
+};
+
+/* Vector of all the known bfd flags.  */
+
+static const single_bfd_flag_info bfd_flag_info[] =
+  {
+    { "ALLOC", SEC_ALLOC },
+    { "LOAD", SEC_LOAD },
+    { "RELOC", SEC_RELOC },
+    { "READONLY", SEC_READONLY },
+    { "CODE", SEC_CODE },
+    { "DATA", SEC_DATA },
+    { "ROM", SEC_ROM },
+    { "CONSTRUCTOR", SEC_CONSTRUCTOR },
+    { "HAS_CONTENTS", SEC_HAS_CONTENTS },
+    { "NEVER_LOAD", SEC_NEVER_LOAD },
+    { "COFF_SHARED_LIBRARY", SEC_COFF_SHARED_LIBRARY },
+    { "IS_COMMON", SEC_IS_COMMON }
+  };
+
+/* For each flag in the global BFD_FLAG_INFO list, if FLAGS has a flag's
+   flagword value set, and STRING contains the flag's name then return
+   true, otherwise return false.  STRING is never nullptr.  */
+
+static bool
 match_bfd_flags (const char *string, flagword flags)
 {
-  if (flags & SEC_ALLOC)
-    if (match_substring (string, "ALLOC"))
-      return 1;
-  if (flags & SEC_LOAD)
-    if (match_substring (string, "LOAD"))
-      return 1;
-  if (flags & SEC_RELOC)
-    if (match_substring (string, "RELOC"))
-      return 1;
-  if (flags & SEC_READONLY)
-    if (match_substring (string, "READONLY"))
-      return 1;
-  if (flags & SEC_CODE)
-    if (match_substring (string, "CODE"))
-      return 1;
-  if (flags & SEC_DATA)
-    if (match_substring (string, "DATA"))
-      return 1;
-  if (flags & SEC_ROM)
-    if (match_substring (string, "ROM"))
-      return 1;
-  if (flags & SEC_CONSTRUCTOR)
-    if (match_substring (string, "CONSTRUCTOR"))
-      return 1;
-  if (flags & SEC_HAS_CONTENTS)
-    if (match_substring (string, "HAS_CONTENTS"))
-      return 1;
-  if (flags & SEC_NEVER_LOAD)
-    if (match_substring (string, "NEVER_LOAD"))
-      return 1;
-  if (flags & SEC_COFF_SHARED_LIBRARY)
-    if (match_substring (string, "COFF_SHARED_LIBRARY"))
-      return 1;
-  if (flags & SEC_IS_COMMON)
-    if (match_substring (string, "IS_COMMON"))
-      return 1;
-
-  return 0;
+  gdb_assert (string != nullptr);
+
+  for (const auto &f : bfd_flag_info)
+    {
+      if (flags & f.value
+	  && match_substring (string, f.name))
+	return true;
+    }
+
+  return false;
 }
 
+/* Print the names of all flags set in FLAGS.  The names are taken from the
+   BFD_FLAG_INFO global.  */
+
 static void
 print_bfd_flags (flagword flags)
 {
-  if (flags & SEC_ALLOC)
-    printf_filtered (" ALLOC");
-  if (flags & SEC_LOAD)
-    printf_filtered (" LOAD");
-  if (flags & SEC_RELOC)
-    printf_filtered (" RELOC");
-  if (flags & SEC_READONLY)
-    printf_filtered (" READONLY");
-  if (flags & SEC_CODE)
-    printf_filtered (" CODE");
-  if (flags & SEC_DATA)
-    printf_filtered (" DATA");
-  if (flags & SEC_ROM)
-    printf_filtered (" ROM");
-  if (flags & SEC_CONSTRUCTOR)
-    printf_filtered (" CONSTRUCTOR");
-  if (flags & SEC_HAS_CONTENTS)
-    printf_filtered (" HAS_CONTENTS");
-  if (flags & SEC_NEVER_LOAD)
-    printf_filtered (" NEVER_LOAD");
-  if (flags & SEC_COFF_SHARED_LIBRARY)
-    printf_filtered (" COFF_SHARED_LIBRARY");
-  if (flags & SEC_IS_COMMON)
-    printf_filtered (" IS_COMMON");
+  for (const auto &f : bfd_flag_info)
+    {
+      if (flags & f.value)
+	printf_filtered (" %s", f.name);
+    }
 }
 
 static void
-maint_print_section_info (const char *name, flagword flags, 
-			  CORE_ADDR addr, CORE_ADDR endaddr, 
+maint_print_section_info (const char *name, flagword flags,
+			  CORE_ADDR addr, CORE_ADDR endaddr,
 			  unsigned long filepos, int addr_size)
 {
   printf_filtered ("    %s", hex_string_custom (addr, addr_size));
@@ -400,27 +392,71 @@ maint_print_all_sections (const char *header, bfd *abfd, objfile *objfile,
     }
 }
 
+/* The options for the "maintenance info sections" command.  */
+
+struct maint_info_sections_opts
+{
+  /* For "-all-objects".  */
+  bool all_objects = false;
+};
+
+static const gdb::option::option_def maint_info_sections_option_defs[] = {
+
+  gdb::option::flag_option_def<maint_info_sections_opts> {
+    "all-objects",
+    [] (maint_info_sections_opts *opts) { return &opts->all_objects; },
+    N_("Display information from all loaded object files."),
+  },
+};
+
+/* Create an option_def_group for the "maintenance info sections" options,
+   with CC_OPTS as context.  */
+
+static inline gdb::option::option_def_group
+make_maint_info_sections_options_def_group (maint_info_sections_opts *cc_opts)
+{
+  return {{maint_info_sections_option_defs}, cc_opts};
+}
+
+/* Completion for the "maintenance info sections" command.  */
+
+static void
+maint_info_sections_completer (struct cmd_list_element *cmd,
+			       completion_tracker &tracker,
+			       const char *text, const char * /* word */)
+{
+  /* Complete command options.  */
+  const auto group = make_maint_info_sections_options_def_group (nullptr);
+  if (gdb::option::complete_options
+      (tracker, &text, gdb::option::PROCESS_OPTIONS_UNKNOWN_IS_ERROR, group))
+    return;
+  const char *word = advance_to_expression_complete_word_point (tracker, text);
+
+  /* Offer completion for section flags, but not section names.  This is
+     only a maintenance command after all, no point going over the top.  */
+  std::vector<const char *> flags;
+  for (const auto &f : bfd_flag_info)
+    flags.push_back (f.name);
+  flags.push_back (nullptr);
+  complete_on_enum (tracker, flags.data (), text, word);
+}
+
 /* Implement the "maintenance info sections" command.  */
 
 static void
 maintenance_info_sections (const char *arg, int from_tty)
 {
-  bool allobj = false;
-
-  /* Only this function cares about the 'ALLOBJ' argument; if 'ALLOBJ' is
-     the only argument, discard it rather than passing it down to
-     print_objfile_section_info (which wouldn't know how to handle it).  */
-  if (arg != nullptr && strcmp (arg, "ALLOBJ") == 0)
-    {
-      arg = nullptr;
-      allobj = true;
-    }
+  /* Check if the "-all-objects" flag was passed.  */
+  maint_info_sections_opts opts;
+  const auto group = make_maint_info_sections_options_def_group (&opts);
+  gdb::option::process_options
+    (&arg, gdb::option::PROCESS_OPTIONS_UNKNOWN_IS_ERROR, group);
 
   for (objfile *ofile : current_program_space->objfiles ())
     {
       if (ofile->obfd == current_program_space->exec_bfd ())
 	maint_print_all_sections (_("Exec file: "), ofile->obfd, ofile, arg);
-      else if (allobj)
+      else if (opts.all_objects)
 	maint_print_all_sections (_("Object file: "), ofile->obfd, ofile, arg);
     }
 
@@ -1062,17 +1098,29 @@ Commands for showing internal info about the program being debugged."),
 			&maintenancelist);
   add_alias_cmd ("i", "info", class_maintenance, 1, &maintenancelist);
 
-  add_cmd ("sections", class_maintenance, maintenance_info_sections, _("\
+  const auto opts = make_maint_info_sections_options_def_group (nullptr);
+  static std::string maint_info_sections_command_help
+    = gdb::option::build_help (_("\
 List the BFD sections of the exec and core files.\n\
-Arguments may be any combination of:\n\
-	[one or more section names]\n\
-	ALLOC LOAD RELOC READONLY CODE DATA ROM CONSTRUCTOR\n\
-	HAS_CONTENTS NEVER_LOAD COFF_SHARED_LIBRARY IS_COMMON\n\
-Sections matching any argument will be listed (no argument\n\
-implies all sections).  In addition, the special argument\n\
-	ALLOBJ\n\
-lists all sections from all object files, including shared libraries."),
-	   &maintenanceinfolist);
+\n\
+Usage: maintenance info sections [-all-objects] [FILTERS]\n\
+\n\
+FILTERS is a list of words, each word is either:\n\
+  + A section name - any section with this name will be printed, or\n\
+  + A section flag - any section with this flag will be printed.  The\n\
+        known flags are:\n\
+	  ALLOC LOAD RELOC READONLY CODE DATA ROM CONSTRUCTOR\n\
+	  HAS_CONTENTS NEVER_LOAD COFF_SHARED_LIBRARY IS_COMMON\n\
+\n\
+Sections matching any of the FILTERS will be listed (no FILTERS implies\n\
+all sections should be printed).\n\
+\n\
+Options:\n\
+%OPTIONS%"), opts);
+  cmd = add_cmd ("sections", class_maintenance, maintenance_info_sections,
+		 maint_info_sections_command_help.c_str (),
+		 &maintenanceinfolist);
+  set_cmd_completer_handle_brkchars (cmd, maint_info_sections_completer);
 
   add_basic_prefix_cmd ("print", class_maintenance,
 			_("Maintenance command for printing GDB internal state."),