Separate snapshot definition

Current snapshot definition is located in the CC module, so it is
difficult to capture non-CC module (such as prebuilt_etc) to the
snapshot. Separate general snapshot definition from cc so other modules
can also define its own snapshot.

Bug: 192430376
Test: m nothing passed
Change-Id: Ifb69fb3d2ec555b629aa31ec03e7ce5831fd3063
diff --git a/snapshot/snapshot_base.go b/snapshot/snapshot_base.go
new file mode 100644
index 0000000..de93f3e
--- /dev/null
+++ b/snapshot/snapshot_base.go
@@ -0,0 +1,104 @@
+// Copyright 2021 The Android Open Source Project
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package snapshot
+
+import (
+	"android/soong/android"
+	"path/filepath"
+)
+
+// Interface for modules which can be captured in the snapshot.
+type SnapshotModuleInterfaceBase interface{}
+
+// Defines the specifics of different images to which the snapshot process is applicable, e.g.,
+// vendor, recovery, ramdisk.
+type SnapshotImage interface {
+	// Returns true if a snapshot should be generated for this image.
+	shouldGenerateSnapshot(ctx android.SingletonContext) bool
+
+	// Function that returns true if the module is included in this image.
+	// Using a function return instead of a value to prevent early
+	// evalution of a function that may be not be defined.
+	InImage(m SnapshotModuleInterfaceBase) func() bool
+
+	// Returns true if a dir under source tree is an SoC-owned proprietary
+	// directory, such as device/, vendor/, etc.
+	//
+	// For a given snapshot (e.g., vendor, recovery, etc.) if
+	// isProprietaryPath(dir, deviceConfig) returns true, then the module in dir
+	// will be built from sources.
+	IsProprietaryPath(dir string, deviceConfig android.DeviceConfig) bool
+
+	// Whether a given module has been explicitly excluded from the
+	// snapshot, e.g., using the exclude_from_vendor_snapshot or
+	// exclude_from_recovery_snapshot properties.
+	ExcludeFromSnapshot(m SnapshotModuleInterfaceBase) bool
+
+	// Returns true if the build is using a snapshot for this image.
+	IsUsingSnapshot(cfg android.DeviceConfig) bool
+
+	// Returns a version of which the snapshot should be used in this target.
+	// This will only be meaningful when isUsingSnapshot is true.
+	TargetSnapshotVersion(cfg android.DeviceConfig) string
+
+	// Whether to exclude a given module from the directed snapshot or not.
+	// If the makefile variable DIRECTED_{IMAGE}_SNAPSHOT is true, directed snapshot is turned on,
+	// and only modules listed in {IMAGE}_SNAPSHOT_MODULES will be captured.
+	ExcludeFromDirectedSnapshot(cfg android.DeviceConfig, name string) bool
+
+	// Returns target image name
+	ImageName() string
+}
+
+type directoryMap map[string]bool
+
+var (
+	// Modules under following directories are ignored. They are OEM's and vendor's
+	// proprietary modules(device/, kernel/, vendor/, and hardware/).
+	defaultDirectoryExcludedMap = directoryMap{
+		"device":   true,
+		"hardware": true,
+		"kernel":   true,
+		"vendor":   true,
+	}
+
+	// Modules under following directories are included as they are in AOSP,
+	// although hardware/ and kernel/ are normally for vendor's own.
+	defaultDirectoryIncludedMap = directoryMap{
+		"kernel/configs":              true,
+		"kernel/prebuilts":            true,
+		"kernel/tests":                true,
+		"hardware/interfaces":         true,
+		"hardware/libhardware":        true,
+		"hardware/libhardware_legacy": true,
+		"hardware/ril":                true,
+	}
+)
+
+func isDirectoryExcluded(dir string, excludedMap directoryMap, includedMap directoryMap) bool {
+	if dir == "." || dir == "/" {
+		return false
+	}
+	if includedMap[dir] {
+		return false
+	} else if excludedMap[dir] {
+		return true
+	} else if defaultDirectoryIncludedMap[dir] {
+		return false
+	} else if defaultDirectoryExcludedMap[dir] {
+		return true
+	} else {
+		return isDirectoryExcluded(filepath.Dir(dir), excludedMap, includedMap)
+	}
+}