grubload/loader.c

   1 #include "minilib.h"
   2 #include "../include/elf.h"
   3
   4 static const unsigned char elf_ident[4] = { 0x7F, 'E', 'L', 'F' };
   5
   6 int load_elf (char * buf, int size) {
   7
   8         Elf32_Ehdr * elf_hdr = (Elf32_Ehdr *) buf;
   9         Elf32_Shdr * elf_sec_hdrs = (Elf32_Shdr *) (buf + elf_hdr->e_shoff);
  10
  11         /* Sanity check on ELF file */
  12         if (memcmp(elf_hdr->e_ident, elf_ident, sizeof(elf_ident))) return -1;
  13         if (elf_hdr->e_type != ET_EXEC) return -1;
  14         if (elf_hdr->e_machine != EM_386) return -1;
  15         if (elf_hdr->e_version != EV_CURRENT) return -1;
  16         if (size < sizeof(Elf32_Ehdr)) return -1;
  17         if (((char *)&elf_sec_hdrs[elf_hdr->e_shnum]) > (buf + size)) return -1;
  18
  19         char * string_table = buf + elf_sec_hdrs[elf_hdr->e_shstrndx].sh_offset;
  20
  21         if (string_table > (buf + size)) return -1;
  22
  23         int i;
  24         for (i = 0; i < elf_hdr->e_shnum; i++) {
  25
  26                 if (elf_sec_hdrs[i].sh_name == SHN_UNDEF) {
  27                         continue;
  28                 }
  29
  30                 char * section_name = string_table + elf_sec_hdrs[i].sh_name;
  31
  32                 if ((elf_sec_hdrs[i].sh_type != SHT_PROGBITS) || !(elf_sec_hdrs[i].sh_flags & SHF_ALLOC)) {
  33                         puts("Skipping ");
  34                         puts(section_name);
  35                         puts("\n");
  36                         continue;
  37                 }
  38
  39                 puts("Loading ");
  40                 puts(section_name);
  41                 puts("\n");
  42
  43                 memcpy(elf_sec_hdrs[i].sh_addr,
  44                        buf + elf_sec_hdrs[i].sh_offset,
  45                        elf_sec_hdrs[i].sh_size);
  46         }
  47
  48         return 0;
  49 }