From 21643c6a89a2ece5cd9a16535a46e10162f585ba Mon Sep 17 00:00:00 2001
From: Spandan Das <spandandas@google.com>
Date: Tue, 18 Mar 2025 22:24:34 +0000
Subject: Add system_other partition props to Soong's misc_info.txt

Implementation Details
- Expand FilesystemInfo with some Avb* props. `system_other` will use
  this info exported by `system` to create system_other entries for
misc_info.txt. This is necessary since system_other does not contain
sufficient information to create a standalone buildPropFile, and reuses
the buildPropFile of system in `build_image` invocation
- Harcode rollback_index to the timestamp parsed from
  `PlatformSecurityPatch`. Most products (including cuttlefish) do not
use a product config variable to override the rollback_index.
Eventually, we should dynamically get this value from one of the vbmeta
partitions.

Bug: 398036609
Test: Built Make and Soong misc_info.txt
Test: No diff in system_other entries

Change-Id: Iadb0ee34d948cb15cd5a59b0dff7bf7fc64024ed
---
 filesystem/filesystem.go   | 17 +++++++++++++
 filesystem/system_other.go | 61 +++++++++++++++++++++++++++++++++++++++++++---
 2 files changed, 74 insertions(+), 4 deletions(-)

diff --git a/filesystem/filesystem.go b/filesystem/filesystem.go
index af14e811a..411770be9 100644
--- a/filesystem/filesystem.go
+++ b/filesystem/filesystem.go
@@ -455,6 +455,14 @@ type FilesystemInfo struct {
 	HasFsverity bool
 
 	PropFileForMiscInfo android.Path
+
+	// Additional avb and partition size information.
+	// `system_other` will use this information of `system` dep for misc_info.txt processing.
+	PartitionSize    *int64
+	UseAvb           bool
+	AvbAlgorithm     string
+	AvbHashAlgorithm string
+	AvbKey           android.Path
 }
 
 // FullInstallPathInfo contains information about the "full install" paths of all the files
@@ -711,6 +719,15 @@ func (f *filesystem) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 		Owners:              f.gatherOwners(specs),
 		HasFsverity:         f.properties.Fsverity.Inputs.GetOrDefault(ctx, nil) != nil,
 		PropFileForMiscInfo: propFileForMiscInfo,
+		PartitionSize:       f.properties.Partition_size,
+	}
+	if proptools.Bool(f.properties.Use_avb) {
+		fsInfo.UseAvb = true
+		fsInfo.AvbAlgorithm = proptools.StringDefault(f.properties.Avb_algorithm, "SHA256_RSA4096")
+		fsInfo.AvbHashAlgorithm = proptools.StringDefault(f.properties.Avb_hash_algorithm, "sha256")
+		if f.properties.Avb_private_key != nil {
+			fsInfo.AvbKey = android.PathForModuleSrc(ctx, *f.properties.Avb_private_key)
+		}
 	}
 
 	android.SetProvider(ctx, FilesystemProvider, fsInfo)
diff --git a/filesystem/system_other.go b/filesystem/system_other.go
index cbfd78b5b..348c01035 100644
--- a/filesystem/system_other.go
+++ b/filesystem/system_other.go
@@ -16,8 +16,11 @@ package filesystem
 
 import (
 	"android/soong/android"
+	"fmt"
 	"path/filepath"
+	"sort"
 	"strings"
+	"time"
 
 	"github.com/google/blueprint"
 	"github.com/google/blueprint/proptools"
@@ -172,10 +175,11 @@ func (m *systemOtherImage) GenerateAndroidBuildActions(ctx android.ModuleContext
 	builder.Build("build_system_other_hermetic", "build system other")
 
 	fsInfo := FilesystemInfo{
-		Output:           output,
-		OutputHermetic:   outputHermetic,
-		RootDir:          stagingDir,
-		FilesystemConfig: m.generateFilesystemConfig(ctx, stagingDir, stagingDirTimestamp),
+		Output:              output,
+		OutputHermetic:      outputHermetic,
+		RootDir:             stagingDir,
+		FilesystemConfig:    m.generateFilesystemConfig(ctx, stagingDir, stagingDirTimestamp),
+		PropFileForMiscInfo: m.buildPropFileForMiscInfo(ctx),
 	}
 
 	android.SetProvider(ctx, FilesystemProvider, fsInfo)
@@ -204,3 +208,52 @@ func (f *systemOtherImage) propFileForHermeticImg(ctx android.ModuleContext, bui
 		Textf(" && echo use_fixed_timestamp=true >> %s", propFilePinnedTimestamp)
 	return propFilePinnedTimestamp
 }
+
+func (f *systemOtherImage) buildPropFileForMiscInfo(ctx android.ModuleContext) android.Path {
+	var lines []string
+	addStr := func(name string, value string) {
+		lines = append(lines, fmt.Sprintf("%s=%s", name, value))
+	}
+
+	addStr("building_system_other_image", "true")
+
+	systemImage := ctx.GetDirectDepProxyWithTag(*f.properties.System_image, systemImageDependencyTag)
+	systemInfo, ok := android.OtherModuleProvider(ctx, systemImage, FilesystemProvider)
+	if !ok {
+		ctx.PropertyErrorf("system_image", "Expected system_image module to provide FilesystemProvider")
+		return nil
+	}
+	if systemInfo.PartitionSize == nil {
+		addStr("system_other_disable_sparse", "true")
+	}
+	if systemInfo.UseAvb {
+		addStr("avb_system_other_hashtree_enable", "true")
+		addStr("avb_system_other_algorithm", systemInfo.AvbAlgorithm)
+		footerArgs := fmt.Sprintf("--hash_algorithm %s", systemInfo.AvbHashAlgorithm)
+		if rollbackIndex, err := f.avbRollbackIndex(ctx); err == nil {
+			footerArgs += fmt.Sprintf(" --rollback_index %d", rollbackIndex)
+		} else {
+			ctx.ModuleErrorf("Could not determine rollback_index %s\n", err)
+		}
+		addStr("avb_system_other_add_hashtree_footer_args", footerArgs)
+		if systemInfo.AvbKey != nil {
+			addStr("avb_system_other_key_path", systemInfo.AvbKey.String())
+		}
+	}
+
+	sort.Strings(lines)
+
+	propFile := android.PathForModuleOut(ctx, "prop_file")
+	android.WriteFileRule(ctx, propFile, strings.Join(lines, "\n"))
+	return propFile
+}
+
+// Use the default: PlatformSecurityPatch
+// TODO: Get this value from vbmeta_system
+func (f *systemOtherImage) avbRollbackIndex(ctx android.ModuleContext) (int64, error) {
+	t, err := time.Parse(time.DateOnly, ctx.Config().PlatformSecurityPatch())
+	if err != nil {
+		return -1, err
+	}
+	return t.Unix(), err
+}
-- 
cgit v1.2.3-59-g8ed1b