cgpt: Add cgpt legacy parameter to set primary GPT signature to IGNOREMEstabilize-8249.B

Now that we have support for the IGNOREME signature in cgpt, we need a
way to set it on an existing disk. The easiest option is to shoehorn
this into the cgpt legacy command, because that's already made to modify
GPT header signatures (really, it would be nice to rename it to cgpt
signature or something, but let's not break existing uses for now).

BRANCH=None
BUG=chrome-os-partner:52595
TEST=unit tests

Change-Id: If2835fec28a9c39373abd050e2e057f73e5ec700
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/340073
Reviewed-by: Nam Nguyen <namnguyen@google.com>

2 files changed, 34 insertions, 4 deletions

diff --git a/cgpt/cgpt_legacy.c b/cgpt/cgpt_legacy.c
index b7582123..d5df34d5 100644
--- a/cgpt/cgpt_legacy.c
+++ b/cgpt/cgpt_legacy.c
@@ -10,6 +10,7 @@
 
 int CgptLegacy(CgptLegacyParams *params) {
   struct drive drive;
+  int gpt_retval;
   GptHeader *h1, *h2;
 
   if (params == NULL)
@@ -19,14 +20,32 @@ int CgptLegacy(CgptLegacyParams *params) {
                            params->drive_size))
     return CGPT_FAILED;
 
+  if (GPT_SUCCESS != (gpt_retval = GptSanityCheck(&drive.gpt))) {
+    Error("GptSanityCheck() returned %d: %s\n",
+          gpt_retval, GptError(gpt_retval));
+    return CGPT_FAILED;
+  }
+
   h1 = (GptHeader *)drive.gpt.primary_header;
   h2 = (GptHeader *)drive.gpt.secondary_header;
-  if (params->efipart) {
+  if (params->mode == CGPT_LEGACY_MODE_EFIPART) {
+    drive.gpt.ignored = MASK_NONE;
     memcpy(h1->signature, GPT_HEADER_SIGNATURE, GPT_HEADER_SIGNATURE_SIZE);
     memcpy(h2->signature, GPT_HEADER_SIGNATURE, GPT_HEADER_SIGNATURE_SIZE);
     RepairEntries(&drive.gpt, MASK_SECONDARY);
     drive.gpt.modified |= (GPT_MODIFIED_HEADER1 | GPT_MODIFIED_ENTRIES1 |
                            GPT_MODIFIED_HEADER2);
+  } else if (params->mode == CGPT_LEGACY_MODE_IGNORE_PRIMARY) {
+    if (!(drive.gpt.valid_headers & MASK_SECONDARY) ||
+        !(drive.gpt.valid_entries & MASK_SECONDARY) ||
+        drive.gpt.ignored & MASK_SECONDARY) {
+      Error("Refusing to mark primary GPT ignored unless secondary is valid.");
+      return CGPT_FAILED;
+    }
+    memset(h1, 0, sizeof(*h1));
+    memcpy(h1->signature, GPT_HEADER_SIGNATURE_IGNORED,
+           GPT_HEADER_SIGNATURE_SIZE);
+    drive.gpt.modified |= GPT_MODIFIED_HEADER1;
   } else {
     memcpy(h1->signature, GPT_HEADER_SIGNATURE2, GPT_HEADER_SIGNATURE_SIZE);
     memcpy(h2->signature, GPT_HEADER_SIGNATURE2, GPT_HEADER_SIGNATURE_SIZE);
diff --git a/cgpt/cmd_legacy.c b/cgpt/cmd_legacy.c
index 5fd742cc..e45b305c 100644
--- a/cgpt/cmd_legacy.c
+++ b/cgpt/cmd_legacy.c
@@ -19,6 +19,7 @@ static void Usage(void)
          "                 default 0, meaning partitions and GPT structs are\n"
          "                 both on DRIVE\n"
          "  -e           Switch GPT header signature back to \"EFI PART\"\n"
+         "  -p           Switch primary GPT header signature to \"IGNOREME\"\n"
          "\n", progname);
 }
 
@@ -31,7 +32,7 @@ int cmd_legacy(int argc, char *argv[]) {
   int errorcnt = 0;
 
   opterr = 0;                     // quiet, you
-  while ((c=getopt(argc, argv, ":heD:")) != -1)
+  while ((c=getopt(argc, argv, ":hepD:")) != -1)
   {
     switch (c)
     {
@@ -44,9 +45,19 @@ int cmd_legacy(int argc, char *argv[]) {
       }
       break;
     case 'e':
-      params.efipart = 1;
+      if (params.mode) {
+        Error("Incompatible flags, pick either -e or -p\n");
+        errorcnt++;
+      }
+      params.mode = CGPT_LEGACY_MODE_EFIPART;
+      break;
+    case 'p':
+      if (params.mode) {
+        Error("Incompatible flags, pick either -e or -p\n");
+        errorcnt++;
+      }
+      params.mode = CGPT_LEGACY_MODE_IGNORE_PRIMARY;
       break;
-
     case 'h':
       Usage();
       return CGPT_OK;