update_engine: Detect supported minor version from conf file.
If the delta minor version is not given as a command line argument, the
payload generator will look for the minor version in
etc/update_engine.conf in the old image.
BUG=chromium:455493
TEST=`FEATURES=test emerge-link update_engine`
CQ-DEPEND=CL:249956
Change-Id: I0f8e3f3c05432169770f2e8e283e8f1fb363def3
Reviewed-on: https://chromium-review.googlesource.com/249955
Reviewed-by: Alex Vakulenko <avakulenko@chromium.org>
Commit-Queue: Allie Wood <alliewood@chromium.org>
Tested-by: Allie Wood <alliewood@chromium.org>
diff --git a/utils.h b/utils.h
index 661a260..8e168f1 100644
--- a/utils.h
+++ b/utils.h
@@ -437,6 +437,14 @@
int64_t* storage,
base::TimeDelta* out_duration);
+// This function looks for a configuration file at |path|. If it finds that
+// file, it will try get the PAYLOAD_MINOR_VERSION value from it and set
+// |minor_version| to that value.
+//
+// The function will return |true| if it succeeds at finding the file and
+// value and setting it, and |false| otherwise.
+bool GetMinorVersion(base::FilePath path, uint32_t* minor_version);
+
} // namespace utils