lib: Clear out LiveUpdate area after consuming all partitions, add checks

Author: fwsGonzo

lib/LiveUpdate/partition.cpp

@@ -20,6 +20,7 @@
 **/
 #include "storage.hpp"
 #include <util/crc32.hpp>
+#include <cassert>
 
 inline uint32_t liu_crc32(const void* buf, size_t len)
 {
@@ -48,6 +49,9 @@ int storage_header::find_partition(const char* key)
     auto& part = ptable.at(p);
     if (strncmp(part.name, key, sizeof(part.name)) == 0)
     {
+      // the partition must have a valid name
+      assert(part.name[0] != 0);
+      // the partition should be fully consistent
       uint32_t chsum = part.generate_checksum(this->vla);
       if (part.crc == chsum) {
         return p;

lib/LiveUpdate/resume.cpp

@@ -101,10 +101,14 @@ void resume_begin(storage_header& storage, std::string key, LiveUpdate::resume_f
     // call next manually only when no one called go_next
     if (oldptr == ptr) ptr = storage.next(ptr);
   }
-  /// wake all the slumbering IP stacks
+  // wake all the slumbering IP stacks
   serialized_tcp::wakeup_ip_networks();
-  /// zero out the partition for security reasons
+  // clear registered resume callbacks
+  resume_funcs.clear();
+  // zero out the partition for security reasons
   storage.zero_partition(p);
+  // if there are no more partitions, clear everything
+  storage.try_zero();
 }
 
 void LiveUpdate::on_resume(uint16_t id, resume_func func)

lib/LiveUpdate/storage.cpp

@@ -162,6 +162,15 @@ uint32_t storage_header::generate_checksum() noexcept
   return checksum;
 }
 
+void storage_header::try_zero() noexcept
+{
+  for (int p = 0; p < partitions; p++) {
+    auto& part = ptable.at(p);
+    if (part.length != 0 && part.name[0] != 0) return;
+  }
+  // zero everything
+  this->zero();
+}
 void storage_header::zero()
 {
   memset(this, 0, sizeof(storage_header) + this->length);

lib/LiveUpdate/storage.hpp

@@ -141,12 +141,13 @@ struct storage_header
   }
   void finalize();
   bool validate() noexcept;
-
-  // zero out the entire header and its data, for extra security
-  void zero();
+  // zero out everything if all partitions consumed
+  void try_zero() noexcept;
 
 private:
   uint32_t generate_checksum() noexcept;
+  // zero out the entire header and its data, for extra security
+  void zero();
 
   uint64_t magic;
   uint32_t crc;

src/kernel/os.cpp

@@ -102,6 +102,8 @@ void OS::shutdown()
 
 void OS::post_start()
 {
+  // if the LiveUpdate storage area is not yet determined,
+  // we can assume its a fresh boot, so calculate new one based on ...
   if (OS::liveupdate_loc_ == 0)
   {
     // default size is 1/4 of heap from the end of memory