Fix incremental builds (when missing a current.txt)

hidl-gen is trying to read some current.txt files that
don't exist. These are newly added in the depfiles.

In the future, two solutions are possible:
- require current.txt in all locations
- build system keeps track of which files are deleted so
  that we can declare a dependency on files we *would*
  read

Fixes: 73352417
Test: hidl_hash_test
Test: m <interface> && m <interface> w/ missing current.txt file
    doesn't rebuild the interface the second time.

Change-Id: Id8b83cf988693d50c7f519513a8c26fe17985a00

1 files changed, 4 insertions, 2 deletions

diff --git a/Coordinator.cpp b/Coordinator.cpp
index 6110c23a..28447784 100644
--- a/Coordinator.cpp
+++ b/Coordinator.cpp
@@ -736,8 +736,10 @@ Coordinator::HashStatus Coordinator::checkHash(const FQName& fqName) const {
 
     std::string hashPath = makeAbsolute(getPackageRootPath(fqName)) + "/current.txt";
     std::string error;
-    onFileAccess(hashPath, "r");
-    std::vector<std::string> frozen = Hash::lookupHash(hashPath, fqName.string(), &error);
+    bool fileExists;
+    std::vector<std::string> frozen =
+        Hash::lookupHash(hashPath, fqName.string(), &error, &fileExists);
+    if (fileExists) onFileAccess(hashPath, "r");
 
     if (error.size() > 0) {
         std::cerr << "ERROR: " << error << std::endl;