RFA/remote: compare-sections

[David Taylor <dtaylor at emc dot com>]

Motivation:

When connecting to a remote system, we use the compare-sections command
to verify that the box is running the code that we think it is running.
Since the system is up and running and *NOT* 'freshly downloaded without
yet executing anything', read-write sections, of course, differ from
what they were in the executable file.

Comparing read-write sections takes time and more importantly the
MIS-MATCHED output is confusing to some users.

The compare-sections command compares all loadable sections including
read-write sections.  This patch gives the user the option to compare
just the loadable read-only sections.

For gdb/ChangeLog:

2014-03-26  David Taylor  <dtaylor@emc.com>

	* remote.c (compare_sections_command): Add -r option to compare
	all loadable read-only sections.

For gdb/doc/ChangeLog:

2014-03-26  David Taylor  <dtaylor@emc.com>

	* gdb.texinfo (compare-sections): Document the new -r (read-only)
	option.

I'm not sure that this patch is big enough to require a copyright
assignment, but regardless, EMC has a copyright assignment on file for
GDB (and GCC and BINUTILS as well).

If it is approved, I will need someone else to commit it as I don't have
write access.

Patch:

Index: gdb/remote.c
===================================================================
RCS file: /home/cvsroot/GDB/gdb/remote.c,v
retrieving revision 1.8
diff -u -r1.8 remote.c
--- gdb/remote.c	26 Mar 2014 14:12:34 -0000	1.8
+++ gdb/remote.c	26 Mar 2014 15:49:40 -0000
@@ -8664,6 +8664,7 @@
   int matched = 0;
   int mismatched = 0;
   int res;
+  int read_only = 0;
 
   if (!exec_bfd)
     error (_("command cannot be used without an exec file"));
@@ -8671,11 +8672,20 @@
   /* Make sure the remote is pointing at the right process.  */
   set_general_process ();
 
+  if (args && (strcmp (args, "-r") == 0))
+    {
+      read_only = 1;
+      args = NULL;
+    }
+
   for (s = exec_bfd->sections; s; s = s->next)
     {
       if (!(s->flags & SEC_LOAD))
 	continue;		/* Skip non-loadable section.  */
 
+      if (read_only && ((s->flags & SEC_READONLY) == 0))
+	continue;		/* Skip writeable sections */
+
       size = bfd_get_section_size (s);
       if (size == 0)
 	continue;		/* Skip zero-length section.  */
@@ -12046,7 +12056,8 @@
 
   add_cmd ("compare-sections", class_obscure, compare_sections_command, _("\
 Compare section data on target to the exec file.\n\
-Argument is a single section name (default: all loaded sections)."),
+Argument is a single section name (default: all loaded sections).\n\
+To compare only read-only loaded sections, specify the -r option."),
 	   &cmdlist);
 
   add_cmd ("packet", class_maintenance, packet_command, _("\
Index: gdb/doc/gdb.texinfo
===================================================================
RCS file: /home/cvsroot/GDB/gdb/doc/gdb.texinfo,v
retrieving revision 1.1.1.2
diff -u -r1.1.1.2 gdb.texinfo
--- gdb/doc/gdb.texinfo	18 Feb 2014 15:36:03 -0000	1.1.1.2
+++ gdb/doc/gdb.texinfo	26 Mar 2014 15:49:40 -0000
@@ -8760,11 +8760,12 @@
 
 @table @code
 @kindex compare-sections
-@item compare-sections @r{[}@var{section-name}@r{]}
+@item compare-sections @r{[}@var{section-name}@r{|}@code{-r}@r{]}
 Compare the data of a loadable section @var{section-name} in the
 executable file of the program being debugged with the same section in
 the remote machine's memory, and report any mismatches.  With no
-arguments, compares all loadable sections.  This command's
+arguments, compares all loadable sections.  With an argument of
+@code{-r}, compares all loadable read-only sections.  This command's
 availability depends on the target's support for the @code{"qCRC"}
 remote request.
 @end table