Add support installing to root of filesystem image

If the partition of a spec is "root", that spec will be installed to
root instead. Normally that spec will be from prebuilt_root module with
install_in_root property.

Bug: 351258461
Test: USE_SOONG_DEFINED_SYSTEM_IMAGE=true m && cvd start
Change-Id: Iaaa9c2fb8a81fe0ba4710c641e1b65c5b71ad4a4

android/packaging.go

@@ -17,6 +17,7 @@ package android
 import (
 	"fmt"
 	"path/filepath"
+	"sort"
 	"strings"
 
 	"github.com/google/blueprint"
@@ -377,31 +378,59 @@ func (p *PackagingBase) GatherPackagingSpecs(ctx ModuleContext) map[string]Packa
 // CopySpecsToDir is a helper that will add commands to the rule builder to copy the PackagingSpec
 // entries into the specified directory.
 func (p *PackagingBase) CopySpecsToDir(ctx ModuleContext, builder *RuleBuilder, specs map[string]PackagingSpec, dir WritablePath) (entries []string) {
-	if len(specs) == 0 {
+	dirsToSpecs := make(map[WritablePath]map[string]PackagingSpec)
+	dirsToSpecs[dir] = specs
+	return p.CopySpecsToDirs(ctx, builder, dirsToSpecs)
+}
+
+// CopySpecsToDirs is a helper that will add commands to the rule builder to copy the PackagingSpec
+// entries into corresponding directories.
+func (p *PackagingBase) CopySpecsToDirs(ctx ModuleContext, builder *RuleBuilder, dirsToSpecs map[WritablePath]map[string]PackagingSpec) (entries []string) {
+	empty := true
+	for _, specs := range dirsToSpecs {
+		if len(specs) > 0 {
+			empty = false
+			break
+		}
+	}
+	if empty {
 		return entries
 	}
+
 	seenDir := make(map[string]bool)
 	preparerPath := PathForModuleOut(ctx, "preparer.sh")
 	cmd := builder.Command().Tool(preparerPath)
 	var sb strings.Builder
 	sb.WriteString("set -e\n")
-	for _, k := range SortedKeys(specs) {
-		ps := specs[k]
-		destPath := filepath.Join(dir.String(), ps.relPathInPackage)
-		destDir := filepath.Dir(destPath)
-		entries = append(entries, ps.relPathInPackage)
-		if _, ok := seenDir[destDir]; !ok {
-			seenDir[destDir] = true
-			sb.WriteString(fmt.Sprintf("mkdir -p %s\n", destDir))
-		}
-		if ps.symlinkTarget == "" {
-			cmd.Implicit(ps.srcPath)
-			sb.WriteString(fmt.Sprintf("cp %s %s\n", ps.srcPath, destPath))
-		} else {
-			sb.WriteString(fmt.Sprintf("ln -sf %s %s\n", ps.symlinkTarget, destPath))
-		}
-		if ps.executable {
-			sb.WriteString(fmt.Sprintf("chmod a+x %s\n", destPath))
+
+	dirs := make([]WritablePath, 0, len(dirsToSpecs))
+	for dir, _ := range dirsToSpecs {
+		dirs = append(dirs, dir)
+	}
+	sort.Slice(dirs, func(i, j int) bool {
+		return dirs[i].String() < dirs[j].String()
+	})
+
+	for _, dir := range dirs {
+		specs := dirsToSpecs[dir]
+		for _, k := range SortedKeys(specs) {
+			ps := specs[k]
+			destPath := filepath.Join(dir.String(), ps.relPathInPackage)
+			destDir := filepath.Dir(destPath)
+			entries = append(entries, ps.relPathInPackage)
+			if _, ok := seenDir[destDir]; !ok {
+				seenDir[destDir] = true
+				sb.WriteString(fmt.Sprintf("mkdir -p %s\n", destDir))
+			}
+			if ps.symlinkTarget == "" {
+				cmd.Implicit(ps.srcPath)
+				sb.WriteString(fmt.Sprintf("cp %s %s\n", ps.srcPath, destPath))
+			} else {
+				sb.WriteString(fmt.Sprintf("ln -sf %s %s\n", ps.symlinkTarget, destPath))
+			}
+			if ps.executable {
+				sb.WriteString(fmt.Sprintf("chmod a+x %s\n", destPath))
+			}
 		}
 	}
 

filesystem/filesystem.go

@@ -312,6 +312,25 @@ func (f *filesystem) buildNonDepsFiles(ctx android.ModuleContext, builder *andro
 	}
 }
 
+func (f *filesystem) copyPackagingSpecs(ctx android.ModuleContext, builder *android.RuleBuilder, specs map[string]android.PackagingSpec, rootDir, rebasedDir android.WritablePath) []string {
+	rootDirSpecs := make(map[string]android.PackagingSpec)
+	rebasedDirSpecs := make(map[string]android.PackagingSpec)
+
+	for rel, spec := range specs {
+		if spec.Partition() == "root" {
+			rootDirSpecs[rel] = spec
+		} else {
+			rebasedDirSpecs[rel] = spec
+		}
+	}
+
+	dirsToSpecs := make(map[android.WritablePath]map[string]android.PackagingSpec)
+	dirsToSpecs[rootDir] = rootDirSpecs
+	dirsToSpecs[rebasedDir] = rebasedDirSpecs
+
+	return f.CopySpecsToDirs(ctx, builder, dirsToSpecs)
+}
+
 func (f *filesystem) buildImageUsingBuildImage(ctx android.ModuleContext) android.OutputPath {
 	rootDir := android.PathForModuleOut(ctx, "root").OutputPath
 	rebasedDir := rootDir
@@ -322,7 +341,7 @@ func (f *filesystem) buildImageUsingBuildImage(ctx android.ModuleContext) androi
 	// Wipe the root dir to get rid of leftover files from prior builds
 	builder.Command().Textf("rm -rf %s && mkdir -p %s", rootDir, rootDir)
 	specs := f.gatherFilteredPackagingSpecs(ctx)
-	f.entries = f.CopySpecsToDir(ctx, builder, specs, rebasedDir)
+	f.entries = f.copyPackagingSpecs(ctx, builder, specs, rootDir, rebasedDir)
 
 	f.buildNonDepsFiles(ctx, builder, rootDir)
 	f.addMakeBuiltFiles(ctx, builder, rootDir)
@@ -465,7 +484,7 @@ func (f *filesystem) buildCpioImage(ctx android.ModuleContext, compressed bool)
 	// Wipe the root dir to get rid of leftover files from prior builds
 	builder.Command().Textf("rm -rf %s && mkdir -p %s", rootDir, rootDir)
 	specs := f.gatherFilteredPackagingSpecs(ctx)
-	f.entries = f.CopySpecsToDir(ctx, builder, specs, rebasedDir)
+	f.entries = f.copyPackagingSpecs(ctx, builder, specs, rootDir, rebasedDir)
 
 	f.buildNonDepsFiles(ctx, builder, rootDir)
 	f.buildFsverityMetadataFiles(ctx, builder, specs, rootDir, rebasedDir)

filesystem/system_image.go

@@ -94,9 +94,10 @@ func (s *systemImage) buildLinkerConfigFile(ctx android.ModuleContext, root andr
 	return output
 }
 
-// Filter the result of GatherPackagingSpecs to discard items targeting outside "system" partition.
-// Note that "apex" module installs its contents to "apex"(fake partition) as well
+// Filter the result of GatherPackagingSpecs to discard items targeting outside "system" / "root"
+// partition.  Note that "apex" module installs its contents to "apex"(fake partition) as well
 // for symbol lookup by imitating "activated" paths.
 func (s *systemImage) filterPackagingSpec(ps android.PackagingSpec) bool {
-	return s.filesystem.filterInstallablePackagingSpec(ps) && ps.Partition() == "system"
+	return s.filesystem.filterInstallablePackagingSpec(ps) &&
+		(ps.Partition() == "system" || ps.Partition() == "root")
 }