feat: abstract interactions with archive/store

internal/slicer/slicer.go

@@ -41,6 +41,15 @@ type contentChecker struct {
 	knownPaths map[string]pathData
 }
 
+// pkgSource holds the resolved source for a package: its architecture and a
+// fetch function returning the package reader and metadata. The fetch
+// function is bound at resolution time, so callers are agnostic to whether
+// the package comes from an archive or a store.
+type pkgSource struct {
+	arch  string
+	fetch func() (io.ReadSeekCloser, *archive.PackageInfo, error)
+}
+
 func (cc *contentChecker) checkMutable(path string) error {
 	if !cc.knownPaths[path].mutable {
 		return fmt.Errorf("cannot write file which is not mutable: %s", path)
@@ -90,7 +99,7 @@ func Run(options *RunOptions) error {
 		targetDir = filepath.Join(dir, targetDir)
 	}
 
-	pkgArchive, err := selectPkgArchives(options.Archives, options.Selection)
+	pkgSources, err := resolvePkgSources(options.Archives, options.Selection)
 	if err != nil {
 		return err
 	}
@@ -108,7 +117,7 @@ func Run(options *RunOptions) error {
 			extractPackage = make(map[string][]tarball.ExtractInfo)
 			extract[slice.Package] = extractPackage
 		}
-		arch := pkgArchive[slice.Package].Options().Arch
+		arch := pkgSources[slice.Package].arch
 		for targetPath, pathInfo := range slice.Contents {
 			if targetPath == "" {
 				continue
@@ -153,7 +162,7 @@ func Run(options *RunOptions) error {
 			continue
 		}
 		pkg := options.Selection.Release.Packages[slice.Package]
-		reader, info, err := pkgArchive[slice.Package].Fetch(pkg.RealName)
+		reader, info, err := pkgSources[pkg.Name].fetch()
 		if err != nil {
 			return err
 		}
@@ -270,7 +279,7 @@ func Run(options *RunOptions) error {
 	// them to the appropriate slices.
 	relPaths := map[string][]*setup.Slice{}
 	for _, slice := range options.Selection.Slices {
-		arch := pkgArchive[slice.Package].Options().Arch
+		arch := pkgSources[slice.Package].arch
 		for relPath, pathInfo := range slice.Contents {
 			if len(pathInfo.Arch) > 0 && !slices.Contains(pathInfo.Arch, arch) {
 				continue
@@ -490,10 +499,13 @@ func createFile(targetDir, relPath string, pathInfo setup.PathInfo) (*fsutil.Ent
 	})
 }
 
-// selectPkgArchives selects the highest priority archive containing the package
-// unless a particular archive is pinned within the slice definition file. It
-// returns a map of archives indexed by package names.
-func selectPkgArchives(archives map[string]archive.Archive, selection *setup.Selection) (map[string]archive.Archive, error) {
+// resolvePkgSources determines the source for each package in the selection.
+// For archive packages it selects the highest priority archive containing the
+// package unless a particular archive is pinned within the slice definition
+// file. For store packages it records a fetch function that returns an error
+// until store support is implemented. It returns a map of pkgSource indexed by
+// package names.
+func resolvePkgSources(archives map[string]archive.Archive, selection *setup.Selection) (map[string]pkgSource, error) {
 	sortedArchives := make([]*setup.Archive, 0, len(selection.Release.Archives))
 	for _, archive := range selection.Release.Archives {
 		if archive.Priority < 0 {
@@ -507,15 +519,20 @@ func selectPkgArchives(archives map[string]archive.Archive, selection *setup.Sel
 		return b.Priority - a.Priority
 	})
 
-	pkgArchive := make(map[string]archive.Archive)
+	pkgSources := make(map[string]pkgSource)
 	for _, s := range selection.Slices {
-		if _, ok := pkgArchive[s.Package]; ok {
+		if _, ok := pkgSources[s.Package]; ok {
 			continue
 		}
 		pkg := selection.Release.Packages[s.Package]
-
 		if pkg.Store != "" {
-			return nil, fmt.Errorf("cannot fetch package %q from store %q: not implemented", pkg.Name, pkg.Store)
+			pkgSources[pkg.Name] = pkgSource{
+				// TODO: set the arch when implementing fetching from the store.
+				fetch: func() (io.ReadSeekCloser, *archive.PackageInfo, error) {
+					return nil, nil, fmt.Errorf("cannot fetch package %q from store %q: not implemented", pkg.Name, pkg.Store)
+				},
+			}
+			continue
 		}
 
 		var candidates []*setup.Archive
@@ -538,7 +555,12 @@ func selectPkgArchives(archives map[string]archive.Archive, selection *setup.Sel
 		if chosen == nil {
 			return nil, fmt.Errorf("cannot find package %q in archive(s)", pkg.RealName)
 		}
-		pkgArchive[pkg.Name] = chosen
+		pkgSources[pkg.Name] = pkgSource{
+			arch: chosen.Options().Arch,
+			fetch: func() (io.ReadSeekCloser, *archive.PackageInfo, error) {
+				return chosen.Fetch(pkg.RealName)
+			},
+		}
 	}
-	return pkgArchive, nil
+	return pkgSources, nil
 }

internal/slicer/slicer_test.go

@@ -1979,21 +1979,29 @@ var slicerTests = []slicerTest{{
 		"/dir/file": "file 0644 cc55e2ec {test-package_third}",
 	},
 }, {
-	summary: "Store package is not yet implemented",
-	slices:  []setup.SliceKey{{"bin-curl", "bin"}},
+	summary: "Store package fetching not yet implemented",
+	slices:  []setup.SliceKey{{"test-package", "myslice"}, {"bin-store-pkg", "myslice"}},
+	arch:    "amd64",
 	release: map[string]string{
 		"chisel.yaml": testutil.DefaultChiselYamlWithStores,
-		"slices/curl.yaml": `
-			package: curl
+		"slices/mydir/test-package.yaml": `
+			package: test-package
+			slices:
+				myslice:
+					contents:
+						/dir/file:
+		`,
+		"slices/mydir/store-pkg.yaml": `
+			package: store-pkg
 			store: bin
-			default-track: latest
+			default-track: 3.1
 			slices:
-				bin:
+				myslice:
 					contents:
-						/usr/bin/curl:
+						/dir/store-file:
 		`,
 	},
-	error: `cannot fetch package "bin-curl" from store "bin": not implemented`,
+	error: `cannot fetch package "bin-store-pkg" from store "bin": not implemented`,
 }}
 
 func (s *S) TestRun(c *C) {