Re: deleting relocs, objcopy and BFD

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Tue, May 2, 2017 at 7:50 AM, Nick Clifton <nickc@redhat.com> wrote:
> Hi Guys,
>
>> Problem 1: incoherence with internal relocs and external relocs breaks> the API.
> I am checking in the attached patch in order to stop objcopy from attempting
> to merge notes when the internal reloc count is greater than the external
> reloc count.  This does not fix the underlying problem, but it should at
> least make objcopy safe, for now.
>
>> b) To remove the API limitation/bug in BFD, somehow.  Maybe adding
>>     end-of-list sentinels to `sec->relocation' and `sec->orelocation',
>>     adjusting `bfd_set_reloc' to install it according to its `relcount'
>>     argument, leaving `sec->reloc_count' untouched, and also making
>>     `elfNN_BE_write_relocs' to use the sentinel when writing.
>
> I think that option b) would be better.  I wonder though whether it might
> be simpler to just let targets override the bfd_set_reloc () function with
> their own implementation, should they have special requirements.  I have not
> investigated this yet, but it seems like it would be the simplest solution,
> provided that it can be made to work.
>

I checked in this to fix build on 32-bit hosts.

-- 
H.J.

From 2ecf0cc317d065cfeb960c61688897351521bce0 Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Tue, 2 May 2017 12:16:26 -0700
Subject: [PATCH] Cast relcount to unsigned long when comparing with
 sec->reloc_count

The type of relcount is long and the type of sec->reloc_count is
unsigned int.  On 32-bit hosts, GCC issues an error:

objcopy.c:2144:20: error: comparison between signed and unsigned integer expressions [-Werror=sign-compare]
       if (relcount > sec->reloc_count)

Cast relcount to unsigned long to silence GCC.

	* objcopy.c (merge_gnu_build_notes): Cast relcount to unsigned
	long when comparing with sec->reloc_count.
---
 binutils/ChangeLog | 5 +++++
 binutils/objcopy.c | 2 +-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/binutils/ChangeLog b/binutils/ChangeLog
index d13dbb6..b3a539a 100644
--- a/binutils/ChangeLog
+++ b/binutils/ChangeLog
@@ -1,3 +1,8 @@
+2017-05-02  H.J. Lu  <hongjiu.lu@intel.com>
+
+	* objcopy.c (merge_gnu_build_notes): Cast relcount to unsigned
+	long when comparing with sec->reloc_count.
+
 2017-05-02  Nick Clifton  <nickc@redhat.com>
 
 	* objcopy.c (merge_gnu_build_notes): Disable merge if there are
diff --git a/binutils/objcopy.c b/binutils/objcopy.c
index 36952ec..ccb5e12 100644
--- a/binutils/objcopy.c
+++ b/binutils/objcopy.c
@@ -2141,7 +2141,7 @@ merge_gnu_build_notes (bfd * abfd, asection * sec, bfd_size_type size, bfd_byte
 	 represent a single external reloc.  Unfortunately the current BFD
 	 API does not handle deleting relocs in such situations very well
 	 and so it is unsafe to proceed.  */
-      if (relcount > sec->reloc_count)
+      if ((unsigned long) relcount > sec->reloc_count)
 	goto done;
 
       /* Eliminate the duplicates.  */
-- 
2.9.3