Fixing the bug of CGPT when primary entry table is invalid.

http://code.google.com/p/chromium-os/issues/detail?id=9279
This issue disclosed a bug of cgpt. The bug comes from the 'show' command always
reads the primary entry table when '-i partition' is specified. I added an
ANY_VALID constant for GetEntry to automatically select valid entry table.

Also fixed the bugs in cmd_boot.c and cmd_find.c. In cmd_add.c, stop user to
continue if any header/entry table is invalid.

Also fixed the bug that untrusted header size could cause segmentation failure.

Hungte, this is FYI. But welcome to do review.

BUG=chromium-os:9279
TEST=RUNTESTS=1 emerge-x86-generic vboot_reference
     Manually tested:
       cgpt show /tmp/test -i 1 -b
       cgpt show /tmp/test
       cgpt add /tmp/test -i 1 -l TEST
       cgpt find /tmp/test -l STATE
       cgpt boot /tmp/test -i 1

Change-Id: Iaba9c635754096a82b3ec74634af184362d4e264
Change-Id: I6f3e87e3998457676e3388d2a6ed36c0564796d8

Review URL: http://codereview.chromium.org/5115002

1 files changed, 7 insertions, 0 deletions

diff --git a/cgpt/cmd_add.c b/cgpt/cmd_add.c
index 21085e71..dafcc50f 100644
--- a/cgpt/cmd_add.c
+++ b/cgpt/cmd_add.c
@@ -198,6 +198,13 @@ int cmd_add(int argc, char *argv[]) {
     return CGPT_FAILED;
   }
 
+  if (((drive.gpt.valid_headers & MASK_BOTH) != MASK_BOTH) ||
+      ((drive.gpt.valid_entries & MASK_BOTH) != MASK_BOTH)) {
+    Error("one of the GPT header/entries is invalid.\n"
+          "please run 'cgpt repair' before adding anything.\n");
+    return CGPT_FAILED;
+  }
+
   uint32_t max_part = GetNumberOfEntries(&drive.gpt);
   if (partition) {
     if (partition > max_part) {