Question wrt libelf

[Marcus Clyne <maccaday at gmail dot com>]

Hi,

I have a question about libelf / gelf.  I know that it's not part of 
binutils, but I couldn't find a mailing list for libelf itself and since 
it's closely related, I hope people don't mind me posting here.

I'm trying to update the information of a global symbol.  I've got as 
far as reading the symbol names, but am unsure how to update the 
information in the symbol.

My code so far is roughly (I've left out the error checks, and when no 
entries match here):

Elf                *e;
Elf_Scn        *scn;
GElf_Shdr    shdr;
GElf_Sym     sym;
Elf_Data     *data;
uint64_t       count, i;
char           *name;

elf_version (EV_CURRENT);
e = elf_begin (fd, ELF_C_RDWR, NULL);

scn = NULL;
while ((scn = elf_nextscn (e, scn)) != NULL) {
   gelf_getshdr (scn, &shdr);

   // break on symbol table
   if (shdr.sh_type == SHT_SYMTAB)
       break;
   }
}

data = elf_getdata (scn, NULL);
count = shdr.sh_size / shdr.sh_entsize;

// find the symbol in the table
for (i = 0; i < count; i++) {
   gelf_getsym (data, i, &sym);
   name = elf_strptr (e, shdr.sh_link, sym.st_name);
   if (strcmp (name, "my_symbol") == 0)
      break;
}

Here's where I'm stuck.  I'd like to be able to access and change the 
value of the symbol, but I'm not sure how to do so and I've not found a 
manual that describes it yet.

Can anyone point me in the right direction?

Thanks,

Marcus.