Re: [PATCH] Fix section symbols in objcopy when removing sections with relocations from Elf objects

[Julian Brown <julian at codesourcery dot com>]

Julian Brown wrote:
> Hi,
>
> This patch fixes a problem where, if sections are removed during objcopy 
> with Elf object files, the section symbols corresponding to the 
> relocation sections for the removed sections may be left in the target 
> object file.

This is a slightly-smarter version (thanks to offlist discussion with 
Dan) which knows about recoving Elf symbols from BFD symbols, hence 
avoids some unnecessary work.

Changelog as before.

Cheers,

Julian
Index: bfd/elf.c
===================================================================
RCS file: /cvs/src/src/bfd/elf.c,v
retrieving revision 1.329
diff -c -p -r1.329 elf.c
*** bfd/elf.c	16 Mar 2006 12:20:15 -0000	1.329
--- bfd/elf.c	24 May 2006 14:21:21 -0000
*************** bfd_section_from_shdr (bfd *abfd, unsign
*** 1935,1940 ****
--- 1935,1941 ----
        BFD_ASSERT (elf_symtab_shndx (abfd) == 0);
        elf_symtab_shndx (abfd) = shindex;
        elf_tdata (abfd)->symtab_shndx_hdr = *hdr;
+       elf_tdata (abfd)->symtab_shndx_section = shindex;
        elf_elfsections (abfd)[shindex] = &elf_tdata (abfd)->symtab_shndx_hdr;
        return TRUE;
  
*************** bfd_section_from_shdr (bfd *abfd, unsign
*** 1944,1949 ****
--- 1945,1951 ----
        if (ehdr->e_shstrndx == shindex)
  	{
  	  elf_tdata (abfd)->shstrtab_hdr = *hdr;
+ 	  elf_tdata (abfd)->shstrtab_section = shindex;
  	  elf_elfsections (abfd)[shindex] = &elf_tdata (abfd)->shstrtab_hdr;
  	  return TRUE;
  	}
*************** bfd_section_from_shdr (bfd *abfd, unsign
*** 1951,1956 ****
--- 1953,1959 ----
  	{
  	symtab_strtab:
  	  elf_tdata (abfd)->strtab_hdr = *hdr;
+ 	  elf_tdata (abfd)->strtab_section = shindex;
  	  elf_elfsections (abfd)[shindex] = &elf_tdata (abfd)->strtab_hdr;
  	  return TRUE;
  	}
Index: binutils/objcopy.c
===================================================================
RCS file: /cvs/src/src/binutils/objcopy.c,v
retrieving revision 1.95
diff -c -p -r1.95 objcopy.c
*** binutils/objcopy.c	28 Feb 2006 16:09:01 -0000	1.95
--- binutils/objcopy.c	24 May 2006 14:21:21 -0000
*************** filter_symbols (bfd *abfd, bfd *obfd, as
*** 915,920 ****
--- 915,945 ----
  	       || undefined
  	       || bfd_is_com_section (bfd_get_section (sym)))
  	keep = strip_symbols != STRIP_UNNEEDED;
+       else if ((flags & BSF_SECTION_SYM) != 0)  /* Section symbol.  */
+         {
+           struct bfd_section *section = sym->section;
+ 
+           keep = 1;
+ 
+           if (!bfd_is_abs_section (section)
+               && is_strip_section (abfd, section))
+ 	    keep = 0;
+           else if (bfd_get_flavour (abfd) == bfd_target_elf_flavour)
+             {
+               Elf_Internal_Shdr **elfsections = elf_elfsections (abfd);
+               elf_symbol_type *elfsym = elf_symbol_from (abfd, sym);
+               unsigned int sec = elfsym->internal_elf_sym.st_shndx;
+               Elf_Internal_Shdr *elfhdr = elfsections[sec];
+               
+               if (elfhdr->sh_type == SHT_REL || elfhdr->sh_type == SHT_RELA)
+                 {
+                   struct bfd_section *targsec =
+                     bfd_section_from_elf_index (abfd, elfhdr->sh_info);
+                   if (targsec && is_strip_section (abfd, targsec))
+                     keep = 0;
+                 }
+             }
+         }
        else if ((flags & BSF_DEBUGGING) != 0)	/* Debugging symbol.  */
  	keep = (strip_symbols != STRIP_DEBUG
  		&& strip_symbols != STRIP_UNNEEDED
*************** filter_symbols (bfd *abfd, bfd *obfd, as
*** 969,975 ****
  	      sym->flags |= BSF_GLOBAL;
  	    }
  
! 	  to[dst_count++] = sym;
  	}
      }
  
--- 994,1002 ----
  	      sym->flags |= BSF_GLOBAL;
  	    }
  
! 	  to[dst_count] = sym;
!           bfd_copy_private_symbol_data (abfd, sym, obfd, to[dst_count]);
!           dst_count++;
  	}
      }