util/grub-module-verifierXX: Add function to calculate section headers

Added the function get_shdr() which returns the section header at a given index
parameter passed into this function. This helps traverse the section header
table and reduces repeated calls to lengthy equations used to obtain section
headers.

Note that it may look as though the argument *arch isn't being used, it's
actually required in order to use the macros grub_target_to_host*(x) which are
unwinded to grub_target_to_host*_real(arch, (x)) based on defines earlier in the
file.

Signed-off-by: Alec Brown <alec.r.brown@oracle.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>

diff --git a/util/grub-module-verifierXX.c b/util/grub-module-verifierXX.c
index ceb24309aecc078a0ac05a3ce13b42e41a43c50d..ad6e79c754218313ba59b6ebac6efb2c7490eb3c 100644 (file)
--- a/util/grub-module-verifierXX.c
+++ b/util/grub-module-verifierXX.c
@@ -131,6 +131,12 @@ grub_target_to_host_real (const struct grub_module_verifier_arch *arch, grub_uin
     return grub_target_to_host32_real (arch, in);
 }
 
+static Elf_Shdr *
+get_shdr (const struct grub_module_verifier_arch *arch, Elf_Ehdr *e, Elf_Word index)
+{
+  return (Elf_Shdr *) ((char *) e + grub_target_to_host (e->e_shoff) +
+                      index * grub_target_to_host16 (e->e_shentsize));
+}
 
 static Elf_Shdr *
 find_section (const struct grub_module_verifier_arch *arch, Elf_Ehdr *e, const char *name)
@@ -139,12 +145,12 @@ find_section (const struct grub_module_verifier_arch *arch, Elf_Ehdr *e, const c
   const char *str;
   unsigned i;
 
-  s = (Elf_Shdr *) ((char *) e + grub_target_to_host (e->e_shoff) + grub_target_to_host16 (e->e_shstrndx) * grub_target_to_host16 (e->e_shentsize));
+  s = get_shdr (arch, e, grub_target_to_host16 (e->e_shstrndx));
   str = (char *) e + grub_target_to_host (s->sh_offset);
 
-  for (i = 0, s = (Elf_Shdr *) ((char *) e + grub_target_to_host (e->e_shoff));
+  for (i = 0, s = get_shdr (arch, e, 0);
        i < grub_target_to_host16 (e->e_shnum);
-       i++, s = (Elf_Shdr *) ((char *) s + grub_target_to_host16 (e->e_shentsize)))
+       i++, s = get_shdr (arch, e, i))
     if (strcmp (str + grub_target_to_host32 (s->sh_name), name) == 0)
       return s;
   return NULL;
@@ -166,13 +172,12 @@ static Elf_Sym *
 get_symtab (const struct grub_module_verifier_arch *arch, Elf_Ehdr *e, Elf_Word *size, Elf_Word *entsize)
 {
   unsigned i;
-  Elf_Shdr *s, *sections;
+  Elf_Shdr *s;
   Elf_Sym *sym;
 
-  sections = (Elf_Shdr *) ((char *) e + grub_target_to_host (e->e_shoff));
-  for (i = 0, s = sections;
+  for (i = 0, s = get_shdr (arch, e, 0);
        i < grub_target_to_host16 (e->e_shnum);
-       i++, s = (Elf_Shdr *) ((char *) s + grub_target_to_host16 (e->e_shentsize)))
+       i++, s = get_shdr (arch, e, i))
     if (grub_target_to_host32 (s->sh_type) == SHT_SYMTAB)
       break;
 
@@ -364,9 +369,9 @@ check_relocations (const char * const modname,
   Elf_Shdr *s;
   unsigned i;
 
-  for (i = 0, s = (Elf_Shdr *) ((char *) e + grub_target_to_host (e->e_shoff));
+  for (i = 0, s = get_shdr (arch, e, 0);
        i < grub_target_to_host16 (e->e_shnum);
-       i++, s = (Elf_Shdr *) ((char *) s + grub_target_to_host16 (e->e_shentsize)))
+       i++, s = get_shdr (arch, e, i))
     if (grub_target_to_host32 (s->sh_type) == SHT_REL || grub_target_to_host32 (s->sh_type) == SHT_RELA)
       {
        Elf_Shdr *ts;
@@ -379,7 +384,7 @@ check_relocations (const char * const modname,
        /* Find the target segment.  */
        if (grub_target_to_host32 (s->sh_info) >= grub_target_to_host16 (e->e_shnum))
          grub_util_error ("%s: orphaned reloc section", modname);
-       ts = (Elf_Shdr *) ((char *) e + grub_target_to_host (e->e_shoff) + grub_target_to_host32 (s->sh_info) * grub_target_to_host16 (e->e_shentsize));
+       ts = get_shdr (arch, e, grub_target_to_host32 (s->sh_info));
 
        section_check_relocations (modname, arch, e, s, grub_target_to_host (ts->sh_size));
       }