From 51509a156bf8fcc5d413459d3edb69a330391e5f Mon Sep 17 00:00:00 2001
From: Paul Duffin <paulduffin@google.com>
Date: Wed, 6 Apr 2022 12:48:09 +0000
Subject: [PATCH] Copy the out/soong/build_number.txt file into sdk snapshots

This change adds the build_number.txt file into the sdk snapshot to
make it easier to debug issues arising in partner builds caused by the
snapshots.

The file is added to the root of the snapshot and is called:
    snapshot-creation-build-number.txt

Bug: 201295663
Test: m nothing
      packages/modules/common/build/mainline_modules_sdks.sh
      # Check the contents of various snapshots.
Change-Id: Ib3ac0cea5c9315cad0b9a3c25d88759097e37163
---
 sdk/testing.go | 23 +++++++++++++++++++++--
 sdk/update.go  |  7 +++++++
 2 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/sdk/testing.go b/sdk/testing.go
index 294f1a57d..062f2000e 100644
--- a/sdk/testing.go
+++ b/sdk/testing.go
@@ -25,6 +25,8 @@ import (
 	"android/soong/cc"
 	"android/soong/genrule"
 	"android/soong/java"
+
+	"github.com/google/blueprint/proptools"
 )
 
 // Prepare for running an sdk test with an apex.
@@ -81,6 +83,11 @@ var prepareForSdkTest = android.GroupFixturePreparers(
 		}
 	}),
 
+	// Add a build number file.
+	android.FixtureModifyProductVariables(func(variables android.FixtureProductVariables) {
+		variables.BuildNumberFile = proptools.StringPtr(BUILD_NUMBER_FILE)
+	}),
+
 	// Make sure that every test provides all the source files.
 	android.PrepareForTestDisallowNonExistentPaths,
 	android.MockFS{
@@ -143,6 +150,8 @@ func getSdkSnapshotBuildInfo(t *testing.T, result *android.TestResult, sdk *sdk)
 	copyRules := &strings.Builder{}
 	otherCopyRules := &strings.Builder{}
 	snapshotDirPrefix := sdk.builderForTests.snapshotDir.String() + "/"
+
+	seenBuildNumberFile := false
 	for _, bp := range buildParams {
 		switch bp.Rule.String() {
 		case android.Cp.String():
@@ -152,8 +161,14 @@ func getSdkSnapshotBuildInfo(t *testing.T, result *android.TestResult, sdk *sdk)
 			src := android.NormalizePathForTesting(bp.Input)
 			// We differentiate between copy rules for the snapshot, and copy rules for the install file.
 			if strings.HasPrefix(output.String(), snapshotDirPrefix) {
-				// Get source relative to build directory.
-				_, _ = fmt.Fprintf(copyRules, "%s -> %s\n", src, dest)
+				// Don't include the build-number.txt file in the copy rules as that would break lots of
+				// tests, just verify that it is copied here as it should appear in every snapshot.
+				if output.Base() == BUILD_NUMBER_FILE {
+					seenBuildNumberFile = true
+				} else {
+					// Get source relative to build directory.
+					_, _ = fmt.Fprintf(copyRules, "%s -> %s\n", src, dest)
+				}
 				info.snapshotContents = append(info.snapshotContents, dest)
 			} else {
 				_, _ = fmt.Fprintf(otherCopyRules, "%s -> %s\n", src, dest)
@@ -189,6 +204,10 @@ func getSdkSnapshotBuildInfo(t *testing.T, result *android.TestResult, sdk *sdk)
 		}
 	}
 
+	if !seenBuildNumberFile {
+		panic(fmt.Sprintf("Every snapshot must include the %s file", BUILD_NUMBER_FILE))
+	}
+
 	info.copyRules = copyRules.String()
 	info.otherCopyRules = otherCopyRules.String()
 
diff --git a/sdk/update.go b/sdk/update.go
index 389e845e7..5db604b7c 100644
--- a/sdk/update.go
+++ b/sdk/update.go
@@ -281,6 +281,10 @@ func appendUniqueVariants(variants []android.SdkAware, newVariant android.SdkAwa
 	return append(variants, newVariant)
 }
 
+// BUILD_NUMBER_FILE is the name of the file in the snapshot zip that will contain the number of
+// the build from which the snapshot was produced.
+const BUILD_NUMBER_FILE = "snapshot-creation-build-number.txt"
+
 // SDK directory structure
 // <sdk_root>/
 //     Android.bp   : definition of a 'sdk' module is here. This is a hand-made one.
@@ -479,6 +483,9 @@ be unnecessary as every module in the sdk already has its own licenses property.
 
 	bp.build(pctx, ctx, nil)
 
+	// Copy the build number file into the snapshot.
+	builder.CopyToSnapshot(ctx.Config().BuildNumberFile(ctx), BUILD_NUMBER_FILE)
+
 	filesToZip := builder.filesToZip
 
 	// zip them all