[Zucchini] Update ExecutableType values.

This change has some pros and some cons:

Pros:
- Human readable ExecType in patch/hex dumps as the ASCII is meaningful.
- Can be done at next to no cost at compile time.
- Assigning new values regardless of order of appearance in the enum is
  more flexible. No more concern over invalidating old patches as values
  will be more or less permanent once this change goes in.

Cons:
- Checking if an ExecutableType is valid requires O(n) time where n
  is the number of supported Exec types using a cast.
  Alternatively, we could maintain a sorted list of these types in
  memory to check against in O(log(n)) or could use a set
  but this is more memory. Overall not a huge deal since we only support
  ~9 types but it is worth understanding the tradeoffs.
- Enums don't enforce value reuse so it is possible although highly
  unlikely we introduce a repeated value. However, given the use of the
  switch case casting requiring unique values this is very unlikely.

Bug: 834932
Change-Id: I7bc14ea7b4434e60bb0dafa47178fb2c2c12dc7f
Reviewed-on: https://chromium-review.googlesource.com/1020446
Commit-Queue: Calder Kitagawa <ckitagawa@google.com>
Reviewed-by: Samuel Huang <huangs@chromium.org>
Cr-Commit-Position: refs/heads/master@{#553083}
NOKEYCHECK=True
GitOrigin-RevId: da4335f0d27c7fa14f6897ffeb0833d424860f7e

1 files changed, 2 insertions, 1 deletions

diff --git a/patch_reader.cc b/patch_reader.cc
index 970b90c..8215405 100644
--- a/patch_reader.cc
+++ b/patch_reader.cc
@@ -4,6 +4,7 @@
 
 #include "components/zucchini/patch_reader.h"
 
+#include <algorithm>
 #include <type_traits>
 #include <utility>
 
@@ -23,7 +24,7 @@ bool ParseElementMatch(BufferSource* source, ElementMatch* element_match) {
   }
   ExecutableType exe_type =
       static_cast<ExecutableType>(element_header.exe_type);
-  if (exe_type >= kNumExeType) {
+  if (CastToExecutableType(exe_type) == kExeTypeUnknown) {
     LOG(ERROR) << "Invalid ExecutableType encountered.";
     LOG(ERROR) << base::debug::StackTrace().ToString();
     return false;