From dadcceea7a8e931eaf970d95a297d8c89a0ebe9d Mon Sep 17 00:00:00 2001
From: Jeff Sharkey <jsharkey@android.com>
Date: Wed, 23 Sep 2015 14:13:45 -0700
Subject: [PATCH] Clean up any/all stale partition tables.

When formatting media as a public volume, we write an MBR, but we
might leave a stale GPT floating around.  Some devices are configured
to aggressively prefer GPT when detected, even if the checksums
between primary/secondary don't match.

To work around this, nuke both MBR and GPT tables from the media
before we lay down our new MBR.

Bug: 24112219
Change-Id: Ibf1be466a6877cbab925a24db5e5dbab0613bea7
---
 Disk.cpp | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/Disk.cpp b/Disk.cpp
index 1e76bee..d5f3e5d 100644
--- a/Disk.cpp
+++ b/Disk.cpp
@@ -340,10 +340,24 @@ status_t Disk::unmountAll() {
 }
 
 status_t Disk::partitionPublic() {
+    int res;
+
     // TODO: improve this code
     destroyAllVolumes();
     mJustPartitioned = true;
 
+    // First nuke any existing partition table
+    std::vector<std::string> cmd;
+    cmd.push_back(kSgdiskPath);
+    cmd.push_back("--zap-all");
+    cmd.push_back(mDevPath);
+
+    // Zap sometimes returns an error when it actually succeeded, so
+    // just log as warning and keep rolling forward.
+    if ((res = ForkExecvp(cmd)) != 0) {
+        LOG(WARNING) << "Failed to zap; status " << res;
+    }
+
     struct disk_info dinfo;
     memset(&dinfo, 0, sizeof(dinfo));