grubload/loader.c

   1 #include <elf.h>
   2
   3 static const unsigned char elf_ident[4] = { 0x7F, 'E', 'L', 'F' };
   4
   5 int load_elf (char * buf, int size) {
   6
   7         Elf32_Ehdr * elf_hdr = (Elf32_Ehdr *) buf;
   8         Elf32_Shdr * elf_sec_hdrs = (Elf32_Shdr *) (buf + elf_hdr->e_shoff);
   9
  10         /* Sanity check on ELF file */
  11         if (memcmp(elf_hdr->e_ident, elf_ident, sizeof(elf_ident))) return -1;
  12         if (elf_hdr->e_type != ET_EXEC) return -1;
  13         if (elf_hdr->e_machine != EM_386) return -1;
  14         if (elf_hdr->e_version != EV_CURRENT) return -1;
  15         if (size < sizeof(Elf32_Ehdr)) return -1;
  16         if (((char *)&elf_sec_hdrs[elf_hdr->e_shnum]) > (buf + size)) return -1;
  17
  18         char * string_table = buf + elf_sec_hdrs[elf_hdr->e_shstrndx].sh_offset;
  19
  20         if (string_table > (buf + size)) return -1;
  21
  22         int i;
  23         for (i = 0; i < elf_hdr->e_shnum; i++) {
  24
  25                 if (elf_sec_hdrs[i].sh_name == SHN_UNDEF) {
  26                         continue;
  27                 }
  28
  29                 char * section_name = string_table + elf_sec_hdrs[i].sh_name;
  30
  31                 if ((elf_sec_hdrs[i].sh_type != SHT_PROGBITS) || !(elf_sec_hdrs[i].sh_flags & SHF_ALLOC)) {
  32                         puts("Skipping ");
  33                         puts(section_name);
  34                         puts("\n");
  35                         continue;
  36                 }
  37
  38                 puts("Loading ");
  39                 puts(section_name);
  40                 puts("\n");
  41
  42                 memcpy(elf_sec_hdrs[i].sh_addr,
  43                        buf + elf_sec_hdrs[i].sh_offset,
  44                        elf_sec_hdrs[i].sh_size);
  45         }
  46
  47         return 0;
  48 }