errors: use NoSuchObject error whenever object is missing

Now that we have a consistent type for reporting whether an error is due
to an object being missing (as opposed to, say, a serious filesystem
error), use that error consistently whenever we have a missing object.
Update the tests to expect this new value as well.

Author: bk2204

file_storer.go

@@ -7,6 +7,8 @@ import (
 	"io/ioutil"
 	"os"
 	"path/filepath"
+
+	"github.com/git-lfs/gitobj/errors"
 )
 
 // fileStorer implements the storer interface by writing to the .git/objects
@@ -34,7 +36,11 @@ func newFileStorer(root, tmp string) *fileStorer {
 // It is the caller's responsibility to close the given file "f" after its use
 // is complete.
 func (fs *fileStorer) Open(sha []byte) (f io.ReadCloser, err error) {
-	return fs.open(fs.path(sha), os.O_RDONLY)
+	f, err = fs.open(fs.path(sha), os.O_RDONLY)
+	if os.IsNotExist(err) {
+		return nil, errors.NoSuchObject(sha)
+	}
+	return f, err
 }
 
 // Store implements the storer.Store function and returns the number of bytes

memory_storer.go

@@ -4,8 +4,9 @@ import (
 	"bytes"
 	"fmt"
 	"io"
-	"os"
 	"sync"
+
+	"github.com/git-lfs/gitobj/errors"
 )
 
 // memoryStorer is an implementation of the storer interface that holds data for
@@ -57,7 +58,7 @@ func (ms *memoryStorer) Open(sha []byte) (f io.ReadCloser, err error) {
 
 	key := fmt.Sprintf("%x", sha)
 	if _, ok := ms.fs[key]; !ok {
-		return nil, os.ErrNotExist
+		return nil, errors.NoSuchObject(sha)
 	}
 	return ms.fs[key], nil
 }

memory_storer_test.go

@@ -5,10 +5,10 @@ import (
 	"encoding/hex"
 	"io"
 	"io/ioutil"
-	"os"
 	"strings"
 	"testing"
 
+	"github.com/git-lfs/gitobj/errors"
 	"github.com/stretchr/testify/assert"
 )
 
@@ -47,7 +47,7 @@ func TestMemoryStorerDoesntOpenMissingEntries(t *testing.T) {
 	ms := newMemoryStorer(nil)
 
 	f, err := ms.Open(hex)
-	assert.Equal(t, os.ErrNotExist, err)
+	assert.Equal(t, errors.NoSuchObject(hex), err)
 	assert.Nil(t, f)
 }
 

object_db.go

@@ -9,6 +9,7 @@ import (
 	"strings"
 	"sync/atomic"
 
+	"github.com/git-lfs/gitobj/errors"
 	"github.com/git-lfs/gitobj/pack"
 )
 
@@ -266,7 +267,7 @@ func (o *ObjectDatabase) save(sha []byte, buf io.Reader) ([]byte, int64, error)
 func (o *ObjectDatabase) open(sha []byte) (*ObjectReader, error) {
 	f, err := o.s.Open(sha)
 	if err != nil {
-		if !os.IsNotExist(err) {
+		if !errors.IsNoSuchObject(err) {
 			// If there was some other issue beyond not being able
 			// to find the object, return that immediately and don't
 			// try and fallback to the *git.ObjectScanner.

pack/set.go

@@ -6,6 +6,8 @@ import (
 	"path/filepath"
 	"regexp"
 	"sort"
+
+	"github.com/git-lfs/gitobj/errors"
 )
 
 // Set allows access of objects stored across a set of packfiles.
@@ -162,8 +164,8 @@ type iterFn func(p *Packfile) (o *Object, err error)
 // returned immediately, if the error is not ErrIsNotFound, or b) continued
 // immediately, if the error is ErrNotFound.
 //
-// If no packfiles match the given file, return ErrIsNotFound, along with no
-// object.
+// If no packfiles match the given file, return errors.NoSuchObject, along with
+// no object.
 func (s *Set) each(name []byte, fn iterFn) (*Object, error) {
 	var key byte
 	if len(name) > 0 {
@@ -181,5 +183,5 @@ func (s *Set) each(name []byte, fn iterFn) (*Object, error) {
 		return o, nil
 	}
 
-	return nil, errNotFound
+	return nil, errors.NoSuchObject(name)
 }