[patch] Fix uninitialized section index internal error

[Joel Brobecker <brobecker at act-europe dot fr>]

Hi,

  it has been pointed to me that it is better to put the change log
inside the mail body rather than putting it inside the patch. So, I'll
start over. Please discard my previous message. Thanks.

While working with gdb on Tru64 5.1, we noticed the following internal
error sometimes happening at the begining of a gdb session:

| gdb/mdebugread.c:2448: gdb-internal-error: Section index is uninitialized
|
| An internal GDB error was detected.  This may make further
| debugging unreliable.  Continue this debugging session? (y or n) n
    
To reproduce the problem, simply compile the following C program:

mach.c:
<<
int
main (void)
{
   return 0;
};
>>

Make sure libmach is linked in when building the program:
% gcc -o mach mach.c -lmach   

After for investigation, I found that gdb was looking for a symbol in
the .bss section of libmach.so, but there is none (which explains why
the section index is not initialized). Instead, there is a .sbss
section, where the symbol is localized.

I modified default_symfile_offsets () to use the .sbss section if the
.bss one does not exist. In that change, I am assuming that a bss and a
sbss section are mutually exclusive.

This change has been integrated in ACT's version of gdb a few months
ago, and has worked well so far.

Here is the change log:

2001-05-10  J. Brobecker <brobecker@act-europe.fr>

        * symfile.c (default_symfile_offsets): use the .sbss section in
        place of the .bss section when the latter does not exist.

-- 
Joel
Index: gdb/symfile.c
===================================================================
RCS file: /cvs/src/src/gdb/symfile.c,v
retrieving revision 1.31
diff -c -3 -p -r1.31 symfile.c
*** symfile.c	2001/04/05 02:02:13	1.31
--- symfile.c	2001/05/10 19:41:39
*************** default_symfile_offsets (struct objfile 
*** 529,534 ****
--- 529,536 ----
      objfile->sect_index_data = sect->index;
  
    sect = bfd_get_section_by_name (objfile->obfd, ".bss");
+   if (!sect)
+     sect = bfd_get_section_by_name (objfile->obfd, ".sbss");
    if (sect) 
      objfile->sect_index_bss = sect->index;