[PATCH] gdb: add gdb_bfd_all_sections for range-based iteration

[Simon Marchi <simon.marchi@polymtl.ca>]

I wanted to make a nicer / type-safe interface for
bfd_map_over_sections, avoiding the `void *` data parameter.

My first shot was to make a wrapper for bfd_map_over_sections,
gdb_bfd_map_over_sections that took a gdb::function_view.

However, I think that a range adapter gives nicer and simpler code, as a
simple for loop is easier to read than a callback / lambda function.  So
here it is, it uses next_iterator and next_adapter, so it's not much
code.

As an example, I ported maintenance_info_sections and friends to use it.
The maint_print_section_data type could probably be removed now, but I
didn't want to do too much in one patch.

gdb/ChangeLog:

	* gdb_bfd.h (gdb_bfd_section_iterator, gdb_bfd_section_range,
	gdb_bfd_all_sections): New.
	* maint.c (print_bfd_section_info): Change param type to
	maint_print_section_data.
	(print_objfile_section_info): Likewise.
	(print_bfd_section_info_maybe_relocated): Likewise.
	(maintenance_info_sections): Use gdb_bfd_all_sections.

Change-Id: Ib496f6b0a0eb7aadb10da1dd381304014d934ea0
---
 gdb/gdb_bfd.h | 18 ++++++++++++++++++
 gdb/maint.c   | 35 ++++++++++++++++-------------------
 2 files changed, 34 insertions(+), 19 deletions(-)

diff --git a/gdb/gdb_bfd.h b/gdb/gdb_bfd.h
index a941b79fe734..3cb50e56e8ac 100644
--- a/gdb/gdb_bfd.h
+++ b/gdb/gdb_bfd.h
@@ -23,6 +23,7 @@
 #include "registry.h"
 #include "gdbsupport/byte-vector.h"
 #include "gdbsupport/gdb_ref_ptr.h"
+#include "gdbsupport/next-iterator.h"
 
 DECLARE_REGISTRY (bfd);
 
@@ -193,4 +194,21 @@ int gdb_bfd_requires_relocations (bfd *abfd);
 bool gdb_bfd_get_full_section_contents (bfd *abfd, asection *section,
 					gdb::byte_vector *contents);
 
+/* Range adapter for a BFD's sections.
+
+   To be used as:
+
+     for (asection *sect : gdb_bfd_all_sections (bfd))
+       ... use SECT ...
+ */
+
+using gdb_bfd_section_iterator = next_iterator<asection>;
+using gdb_bfd_section_range = next_adapter<asection, gdb_bfd_section_iterator>;
+
+static inline
+gdb_bfd_section_range gdb_bfd_all_sections (bfd *abfd)
+{
+  return gdb_bfd_section_range (abfd->sections);
+}
+
 #endif /* GDB_BFD_H */
diff --git a/gdb/maint.c b/gdb/maint.c
index 3368769ad96f..8adac24efcb0 100644
--- a/gdb/maint.c
+++ b/gdb/maint.c
@@ -266,7 +266,7 @@ struct maint_print_section_data
   maint_print_section_data (struct objfile *objfile, const char *arg,
 			    bfd *abfd)
     : objfile (objfile),
-      arg(arg)
+      arg (arg)
   {
     int section_count = gdb_bfd_count_sections (abfd);
     index_digits = ((int) log10 ((float) section_count)) + 1;
@@ -292,20 +292,18 @@ print_section_index (bfd *abfd,
   printf_filtered ("%-*s", (index_digits + 4), result.c_str ());
 }
 
-/* Print information about ASECT from ABFD.  DATUM holds a pointer to a
-   maint_print_section_data object.  The section will be printed using the
-   VMA's from the bfd, which will not be the relocated addresses for bfds
-   that should be relocated.  The information must be printed with the
-   same layout as PRINT_OBJFILE_SECTION_INFO below.  */
+/* Print information about ASECT from ABFD.  The section will be printed using
+   the VMA's from the bfd, which will not be the relocated addresses for bfds
+   that should be relocated.  The information must be printed with the same
+   layout as PRINT_OBJFILE_SECTION_INFO below.  */
 
 static void
 print_bfd_section_info (bfd *abfd,
 			asection *asect,
-			void *datum)
+			const maint_print_section_data *print_data)
 {
   flagword flags = bfd_section_flags (asect);
   const char *name = bfd_section_name (asect);
-  maint_print_section_data *print_data = (maint_print_section_data *) datum;
   const char *arg = print_data->arg;
 
   if (arg == NULL || *arg == '\0'
@@ -332,7 +330,7 @@ print_bfd_section_info (bfd *abfd,
 static void
 print_objfile_section_info (bfd *abfd,
 			    struct obj_section *asect,
-			    maint_print_section_data *print_data)
+			    const maint_print_section_data *print_data)
 {
   flagword flags = bfd_section_flags (asect->the_bfd_section);
   const char *name = bfd_section_name (asect->the_bfd_section);
@@ -376,16 +374,14 @@ maint_obj_section_from_bfd_section (bfd *abfd,
   return osect;
 }
 
-/* Print information about ASECT from ABFD.  DATUM holds a pointer to a
-   maint_print_section_data object.  Where possible the information for
+/* Print information about ASECT from ABFD.  Where possible the information for
    ASECT will print the relocated addresses of the section.  */
 
 static void
 print_bfd_section_info_maybe_relocated (bfd *abfd,
 					asection *asect,
-					void *datum)
+					const maint_print_section_data *print_data)
 {
-  maint_print_section_data *print_data = (maint_print_section_data *) datum;
   objfile *objfile = print_data->objfile;
 
   gdb_assert (objfile->sections != NULL);
@@ -393,7 +389,7 @@ print_bfd_section_info_maybe_relocated (bfd *abfd,
     = maint_obj_section_from_bfd_section (abfd, asect, objfile);
 
   if (osect->the_bfd_section == NULL)
-    print_bfd_section_info (abfd, asect, datum);
+    print_bfd_section_info (abfd, asect, print_data);
   else
     print_objfile_section_info (abfd, osect, print_data);
 }
@@ -432,9 +428,9 @@ maintenance_info_sections (const char *arg, int from_tty)
 
 	  maint_print_section_data print_data (ofile, arg, ofile->obfd);
 
-	  bfd_map_over_sections (ofile->obfd,
-				 print_bfd_section_info_maybe_relocated,
-				 (void *) &print_data);
+	  for (asection *sect : gdb_bfd_all_sections (ofile->obfd))
+	    print_bfd_section_info_maybe_relocated (ofile->obfd, sect,
+						    &print_data);
 	}
     }
 
@@ -446,8 +442,9 @@ maintenance_info_sections (const char *arg, int from_tty)
       printf_filtered ("    `%s', ", bfd_get_filename (core_bfd));
       wrap_here ("        ");
       printf_filtered (_("file type %s.\n"), bfd_get_target (core_bfd));
-      bfd_map_over_sections (core_bfd, print_bfd_section_info,
-			     (void *) &print_data);
+
+      for (asection *sect : gdb_bfd_all_sections (core_bfd))
+	print_bfd_section_info (core_bfd, sect, &print_data);
     }
 }
 
-- 
2.28.0