bfd client access to PT_NOTE program segment

bfd client access to PT_NOTE program segment

[fnf]

I've been looking for an easy way for a bfd client such as gdb to
identify which program segment in an ELF format core file is the
PT_NOTE section.

One somewhat obvious way is to change the synthetic segment names that
BFD generates to something more meaningful than "segmentN" and then
select the BFD section based on the name.  The following patch to
elf.c (non context, for discussion purposes only) seems to do the job:

  1403c1406,1417
  <   sprintf (namebuf, split ? "segment%da" : "segment%d", index);
  ---
  >   switch (hdr->p_type)
  >     {
  >     case PT_NULL: s = "null"; break;
  >     case PT_LOAD: s = "load"; break;
  >     case PT_DYNAMIC: s = "dynamic"; break;
  >     case PT_INTERP: s = "interp"; break;
  >     case PT_NOTE: s = "note"; break;
  >     case PT_SHLIB: s = "shlib"; break;
  >     case PT_PHDR: s = "phdr"; break;
  >     default: s = "segment"; break;
  >     }
  >   sprintf (namebuf, "%s%d%s", s, index, split ? "a" : "");
  1434c1448
  <       sprintf (namebuf, "segment%db", index);
  ---
  >       sprintf (namebuf, "%s%d%b", s, index);

Then objdump produces (abbreviated) something like:

  0 note0         000004fc  00000000  00000000  00000174  2**0
  1 .reg/2632     00000044  00000000  00000000  000001cc  2**2
  2 .reg          00000044  00000000  00000000  000001cc  2**2
  3 load1         00000000  08048000  00000000  00001000  2**0
  4 load2         00001000  08049000  00000000  00001000  2**0
  5 load3         00000000  40000000  00000000  00002000  2**0
  6 load4         00001000  40012000  00000000  00002000  2**0
  7 load5         00001000  40013000  00000000  00003000  2**0
  8 load6         00000000  4001a000  00000000  00004000  2**0
  9 load7         00005000  40100000  00000000  00004000  2**0
 10 load8         00003000  40105000  00000000  00009000  2**0
 11 load9         00002000  bfffe000  00000000  0000c000  2**0

Comments about the idea of trying to generate more meaningful
BFD section names?  Of using them in a BFD client?  Any better
suggestions for identifying the PT_NOTE segment?

-Fred

bfd client access to PT_NOTE program segment (patch included)

[fnf]

I didn't get any feedback, pro or con, to my previous email, so
I assume there are no real objections to making this change.
Would someone with access to the repository please apply this
patch?  It won't hurt my feelings if you see a need to tweak
it slightly for some reason.  :-)

-Fred

===================================================================

   1999-09-22  Fred Fish  <fnf@cygnus.com>

	* elf.c (bfd_section_from_phdr): Add typename variable.  Use p_type
	to initialize it to something meaningful.  Then use it to generate
	more useful segment names.

Index: elf.c
===================================================================
RCS file: /cvs/binutils/binutils/bfd/elf.c,v
retrieving revision 1.16
diff -c -p -r1.16 elf.c
*** elf.c	1999/09/04 17:07:46	1.16
--- elf.c	1999/09/23 02:57:39
*************** bfd_section_from_phdr (abfd, hdr, index)
*** 1394,1406 ****
  {
    asection *newsect;
    char *name;
    char namebuf[64];
    int split;
  
    split = ((hdr->p_memsz > 0)
  	    && (hdr->p_filesz > 0)
  	    && (hdr->p_memsz > hdr->p_filesz));
!   sprintf (namebuf, split ? "segment%da" : "segment%d", index);
    name = bfd_alloc (abfd, strlen (namebuf) + 1);
    if (!name)
      return false;
--- 1394,1418 ----
  {
    asection *newsect;
    char *name;
+   char *typename;
    char namebuf[64];
    int split;
  
    split = ((hdr->p_memsz > 0)
  	    && (hdr->p_filesz > 0)
  	    && (hdr->p_memsz > hdr->p_filesz));
!   switch (hdr->p_type)
!     {
!     case PT_NULL: typename = "null"; break;
!     case PT_LOAD: typename = "load"; break;
!     case PT_DYNAMIC: typename = "dynamic"; break;
!     case PT_INTERP: typename = "interp"; break;
!     case PT_NOTE: typename = "note"; break;
!     case PT_SHLIB: typename = "shlib"; break;
!     case PT_PHDR: typename = "phdr"; break;
!     default: typename = "segment"; break;
!     }
!   sprintf (namebuf, "%s%d%s", typename, index, split ? "a" : "");
    name = bfd_alloc (abfd, strlen (namebuf) + 1);
    if (!name)
      return false;
*************** bfd_section_from_phdr (abfd, hdr, index)
*** 1431,1437 ****
  
    if (split)
      {
!       sprintf (namebuf, "segment%db", index);
        name = bfd_alloc (abfd, strlen (namebuf) + 1);
        if (!name)
  	return false;
--- 1443,1449 ----
  
    if (split)
      {
!       sprintf (namebuf, "%s%db", typename, index);
        name = bfd_alloc (abfd, strlen (namebuf) + 1);
        if (!name)
  	return false;

Re: bfd client access to PT_NOTE program segment (patch included)

[Richard Henderson]

On Wed, Sep 22, 1999 at 08:10:10PM -0700, fnf@www.ninemoons.com wrote:
>    1999-09-22  Fred Fish  <fnf@cygnus.com>
> 
> 	* elf.c (bfd_section_from_phdr): Add typename variable.  Use p_type
> 	to initialize it to something meaningful.  Then use it to generate
> 	more useful segment names.

Applied.


r~