Error reading symbols...

Error reading symbols...

[Scott Bambrough]

Good day,

I get the following error when running a small dynamically linked test program:
"During symbol reading, register number 258 too large (max 26)  in symbol buf.".

This error occurs in the following chunk of code when process_one_symbol is
passed a bogus value in nlist.n_value.  It looks to me like the macro
INTERNALIZE_SYMBOL is the cause of the problem.

  /* lines 1817 - 1831 from dbxread.c */
  if (symbuf_idx == symbuf_end)
     fill_symbuf (abfd);
  bufp = &symbuf[symbuf_idx++];
  INTERNALIZE_SYMBOL (nlist, bufp, abfd);
  OBJSTAT (objfile, n_stabs++);

  type = bfd_h_get_8 (abfd, bufp->e_type);

  SET_NAMESTRING ();

  if (type & N_STAB)
    {
      process_one_symbol (type, nlist.n_desc, nlist.n_value,
                          namestring, section_offsets, objfile);
    }

When the problem occurs GDB is processing the following stab:

  "buf:r(0,44)=*(0,45)=ar(0,1);0;-1;(0,2)"

If I set a breakpoint on the complain() call in define_symbol I get the
following stack frame:

(top-gdb) bt
#0  define_symbol (valu=258, string=0x2 <Address 0x2 out of bounds>,
    desc=1469, type=64, objfile=0x22d6bc0)
    at ../../gdb-5.0/gdb/stabsread.c:1875
#1  0x020bc82c in process_one_symbol (type=64, desc=1469, valu=258,
    name=0x2311ab3 "buf:r(0,44)=*(0,45)=ar(0,1);0;-1;(0,2)",
    section_offsets=0x22fa678, objfile=0x22d6bc0)
    at ../../gdb-5.0/gdb/dbxread.c:2402
#2  0x020bbd6c in read_ofile_symtab (pst=0x2320cdc)
    at ../../gdb-5.0/gdb/dbxread.c:1829
#3  0xbffff304 in ?? ()
(top-gdb)

If I switch to frame #2 I have the following data values:
 
(top-gdb) p *bufp
$42 = {e_strx = "buf:", e_type = "r", e_other = "(", e_desc = "0,",
  e_value = "44)="}

(top-gdb) p nlist
$43 = {n_strx = 24579, n_type = 64 '@', n_other = 0 '\000', n_desc = 1469,
  n_value = 258}

I don't understand what is supposed to go on here.  Given the values of the bufp
members and the definitions of INTERNALIZE_SYMBOL, bfd_h_32, and bfd_getl32
which follow I don't see how this should ever work.

The question is are the contents of bufp wrong or is the bfd_h_get_32 function
misbehaving?  I suspect the former, but I'm not truly up to speed on the symbol
side of things in GDB.  Can someone have a look and point me in the correct
direction?

/* macro from dbxread.c
#define INTERNALIZE_SYMBOL(intern, extern, abfd)                        \
  {                                                                     \
    (intern).n_type = bfd_h_get_8 (abfd, (extern)->e_type);             \
    (intern).n_strx = bfd_h_get_32 (abfd, (extern)->e_strx);            \
    (intern).n_desc = bfd_h_get_16 (abfd, (extern)->e_desc);            \
    (intern).n_value = bfd_h_get_32 (abfd, (extern)->e_value);          \
  }

/* from bfd-in2l.h and elf32-target.h */
bfd_h_get_32 == bfd_getl32

/* from libbfd.c */
bfd_vma
bfd_getl32 (addr)
     register const bfd_byte *addr;
{
  unsigned long v;

  v = (unsigned long) addr[0];
  v |= (unsigned long) addr[1] << 8;
  v |= (unsigned long) addr[2] << 16;
  v |= (unsigned long) addr[3] << 24;
  return (bfd_vma) v;
}

Scott
-- 
Scott Bambrough - Software Engineer
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