/**
* @brief Search an entire open ELF object for a named symbol
*
* @param elf THe open ELF object
* @param name The symbol name to find
*
* @returns The address to which the symbol points, 0 otherwise.
*/
static GElf_Addr elf_getsymaddr_byname(Elf *elf, const char * name) {
uint32_t symtab_idx = 0;
Elf_Scn *symtab;
GElf_Addr addr = 0;
symtab = elf_getsymtab(elf, &symtab_idx);
while(symtab != NULL) {
addr = elf_scn_getsymaddr_byname(elf, symtab, name);
if (addr) {
return addr;
}
symtab_idx++;
symtab = elf_getsymtab(elf, &symtab_idx);
}
return 0;
}
static void
elf_reloc_apply(const char *p, const char *shstab, size_t shstabsz,
ssize_t sidx, char *sdata, size_t ssz)
{
Elf_Ehdr *eh = (Elf_Ehdr *)p;
Elf_Shdr *sh;
Elf_Rel *rel = NULL;
Elf_RelA *rela = NULL;
const Elf_Sym *symtab, *sym;
ssize_t symtabidx;
size_t nsymb, rsym, rtyp, roff;
size_t i, j;
uint64_t value;
int rsize;
/* Find symbol table location and number of symbols. */
symtabidx = elf_getsymtab(p, shstab, shstabsz, &symtab, &nsymb);
if (symtabidx == -1) {
warnx("symbol table not found");
return;
}
/* Apply possible relocation. */
for (i = 0; i < eh->e_shnum; i++) {
sh = (Elf_Shdr *)(p + eh->e_shoff + i * eh->e_shentsize);
if (sh->sh_size == 0)
continue;
if ((sh->sh_info != sidx) || (sh->sh_link != symtabidx))
continue;
switch (sh->sh_type) {
case SHT_RELA:
rela = (Elf_RelA *)(p + sh->sh_offset);
for (j = 0; j < (sh->sh_size / sizeof(Elf_RelA)); j++) {
rsym = ELF_R_SYM(rela[j].r_info);
rtyp = ELF_R_TYPE(rela[j].r_info);
roff = rela[j].r_offset;
if (rsym >= nsymb)
continue;
sym = &symtab[rsym];
value = sym->st_value + rela[j].r_addend;
rsize = elf_reloc_size(rtyp);
if (rsize == -1 || roff + rsize >= ssz)
continue;
ELF_WRITE_RELOC(sdata + roff, value, rsize);
}
break;
case SHT_REL:
rel = (Elf_Rel *)(p + sh->sh_offset);
for (j = 0; j < (sh->sh_size / sizeof(Elf_Rel)); j++) {
rsym = ELF_R_SYM(rel[j].r_info);
rtyp = ELF_R_TYPE(rel[j].r_info);
roff = rel[j].r_offset;
if (rsym >= nsymb)
continue;
sym = &symtab[rsym];
value = sym->st_value;
rsize = elf_reloc_size(rtyp);
if (rsize == -1 || roff + rsize >= ssz)
continue;
ELF_WRITE_RELOC(sdata + roff, value, rsize);
}
break;
default:
continue;
}
}
}
