pack: pass hash algorithm down into pack instantiation

When we instantiate a new pack or set of packs, pass the hash algorithm
into these functions.

Author: bk2204

backend.go

@@ -21,17 +21,17 @@ import (
 // the algo parameter.
 func NewFilesystemBackend(root, tmp, alternates string, algo hash.Hash) (storage.Backend, error) {
 	fsobj := newFileStorer(root, tmp)
-	packs, err := pack.NewStorage(root)
+	packs, err := pack.NewStorage(root, algo)
 	if err != nil {
 		return nil, err
 	}
 
-	storage, err := findAllBackends(fsobj, packs, root)
+	storage, err := findAllBackends(fsobj, packs, root, algo)
 	if err != nil {
 		return nil, err
 	}
 
-	storage, err = addAlternatesFromEnvironment(storage, alternates)
+	storage, err = addAlternatesFromEnvironment(storage, alternates, algo)
 	if err != nil {
 		return nil, err
 	}
@@ -42,7 +42,7 @@ func NewFilesystemBackend(root, tmp, alternates string, algo hash.Hash) (storage
 	}, nil
 }
 
-func findAllBackends(mainLoose *fileStorer, mainPacked *pack.Storage, root string) ([]storage.Storage, error) {
+func findAllBackends(mainLoose *fileStorer, mainPacked *pack.Storage, root string, algo hash.Hash) ([]storage.Storage, error) {
 	storage := make([]storage.Storage, 2)
 	storage[0] = mainLoose
 	storage[1] = mainPacked
@@ -58,7 +58,7 @@ func findAllBackends(mainLoose *fileStorer, mainPacked *pack.Storage, root strin
 
 	scanner := bufio.NewScanner(f)
 	for scanner.Scan() {
-		storage, err = addAlternateDirectory(storage, scanner.Text())
+		storage, err = addAlternateDirectory(storage, scanner.Text(), algo)
 		if err != nil {
 			return nil, err
 		}
@@ -71,24 +71,24 @@ func findAllBackends(mainLoose *fileStorer, mainPacked *pack.Storage, root strin
 	return storage, nil
 }
 
-func addAlternateDirectory(s []storage.Storage, dir string) ([]storage.Storage, error) {
+func addAlternateDirectory(s []storage.Storage, dir string, algo hash.Hash) ([]storage.Storage, error) {
 	s = append(s, newFileStorer(dir, ""))
-	pack, err := pack.NewStorage(dir)
+	pack, err := pack.NewStorage(dir, algo)
 	if err != nil {
 		return s, err
 	}
 	s = append(s, pack)
 	return s, nil
 }
 
-func addAlternatesFromEnvironment(s []storage.Storage, env string) ([]storage.Storage, error) {
+func addAlternatesFromEnvironment(s []storage.Storage, env string, algo hash.Hash) ([]storage.Storage, error) {
 	if len(env) == 0 {
 		return s, nil
 	}
 
 	for _, dir := range splitAlternateString(env, alternatesSeparator) {
 		var err error
-		s, err = addAlternateDirectory(s, dir)
+		s, err = addAlternateDirectory(s, dir, algo)
 		if err != nil {
 			return nil, err
 		}

pack/set.go

@@ -2,6 +2,7 @@ package pack
 
 import (
 	"fmt"
+	"hash"
 	"os"
 	"path/filepath"
 	"regexp"
@@ -38,7 +39,7 @@ var (
 // containing them. If there was an error parsing the packfiles in that
 // directory, or the directory was otherwise unable to be observed, NewSet
 // returns that error.
-func NewSet(db string) (*Set, error) {
+func NewSet(db string, algo hash.Hash) (*Set, error) {
 	pd := filepath.Join(db, "pack")
 
 	paths, err := filepath.Glob(filepath.Join(escapeGlobPattern(pd), "*.pack"))

pack/storage.go

@@ -1,6 +1,7 @@
 package pack
 
 import (
+	"hash"
 	"io"
 )
 
@@ -10,8 +11,8 @@ type Storage struct {
 }
 
 // NewStorage returns a new storage object based on a pack set.
-func NewStorage(root string) (*Storage, error) {
-	packs, err := NewSet(root)
+func NewStorage(root string, algo hash.Hash) (*Storage, error) {
+	packs, err := NewSet(root, algo)
 	if err != nil {
 		return nil, err
 	}