pkg/sif/create.go

@@ -322,51 +322,6 @@ func CreateContainerAtPath(path string, opts ...CreateOpt) (*FileImage, error) {
 	return f, nil
 }
 
-func zeroData(fimg *FileImage, descr *rawDescriptor) error {
-	// first, move to data object offset
-	if _, err := fimg.rw.Seek(descr.Offset, io.SeekStart); err != nil {
-		return err
-	}
-
-	var zero [4096]byte
-	n := descr.Size
-	upbound := int64(4096)
-	for {
-		if n < 4096 {
-			upbound = n
-		}
-
-		if _, err := fimg.rw.Write(zero[:upbound]); err != nil {
-			return err
-		}
-		n -= 4096
-		if n <= 0 {
-			break
-		}
-	}
-
-	return nil
-}
-
-func resetDescriptor(fimg *FileImage, index int) error {
-	// If we remove the primary partition, set the global header Arch field to HdrArchUnknown
-	// to indicate that the SIF file doesn't include a primary partition and no dependency
-	// on any architecture exists.
-	if fimg.rds[index].isPartitionOfType(PartPrimSys) {
-		fimg.h.Arch = hdrArchUnknown
-	}
-
-	offset := fimg.h.DescriptorsOffset + int64(index)*int64(binary.Size(fimg.rds[0]))
-
-	// first, move to descriptor offset
-	if _, err := fimg.rw.Seek(offset, io.SeekStart); err != nil {
-		return err
-	}
-
-	var emptyDesc rawDescriptor
-	return binary.Write(fimg.rw, binary.LittleEndian, emptyDesc)
-}
-
 // addOpts accumulates object add options.
 type addOpts struct {
 	t time.Time
@@ -448,6 +403,26 @@ func (f *FileImage) isLast(d *rawDescriptor) bool {
 	return isLast
 }
 
+// zeroReader is an io.Reader that returns a stream of zero-bytes.
+type zeroReader struct{}
+
+func (zeroReader) Read(b []byte) (int, error) {
+	for i := range b {
+		b[i] = 0
+	}
+	return len(b), nil
+}
+
+// zero overwrites the data object described by d with a stream of zero bytes.
+func (f *FileImage) zero(d *rawDescriptor) error {
+	if _, err := f.rw.Seek(d.Offset, io.SeekStart); err != nil {
+		return err
+	}
+
+	_, err := io.CopyN(f.rw, zeroReader{}, d.Size)
+	return err
+}
+
 // truncateAt truncates f at the start of the padded data object described by d.
 func (f *FileImage) truncateAt(d *rawDescriptor) error {
 	start := d.Offset + d.Size - d.SizeWithPadding
@@ -531,7 +506,7 @@ func (f *FileImage) DeleteObject(id uint32, opts ...DeleteOpt) error {
 	}
 
 	if do.zero {
-		if err := zeroData(f, d); err != nil {
+		if err := f.zero(d); err != nil {
 			return fmt.Errorf("%w", err)
 		}
 	}
@@ -547,15 +522,17 @@ func (f *FileImage) DeleteObject(id uint32, opts ...DeleteOpt) error {
 	f.h.DescriptorsFree++
 	f.h.ModifiedAt = do.t.Unix()
 
-	index := 0
-	for i, od := range f.rds {
-		if od.ID == id {
-			index = i
-			break
-		}
+	// If we remove the primary partition, set the global header Arch field to HdrArchUnknown
+	// to indicate that the SIF file doesn't include a primary partition and no dependency
+	// on any architecture exists.
+	if d.isPartitionOfType(PartPrimSys) {
+		f.h.Arch = hdrArchUnknown
 	}
 
-	if err := resetDescriptor(f, index); err != nil {
+	// Reset rawDescripter with empty struct
+	*d = rawDescriptor{}
+
+	if err := f.writeDescriptors(); err != nil {
 		return fmt.Errorf("%w", err)
 	}
 
@@ -678,7 +655,7 @@ func (f *FileImage) SetPrimPart(id uint32, opts ...SetOpt) error {
 	return nil
 }
 
-// SetMetadata the metadata of the data object with id to md, according to opts.
+// SetMetadata sets the metadata of the data object with id to md, according to opts.
 //
 // By default, the image/object modification times are set to the current time for
 // non-deterministic images, and unset otherwise. To override this, consider using

pkg/sif/create_test.go

@@ -548,6 +548,69 @@ func TestDeleteObject(t *testing.T) {
 	}
 }
 
+func TestDeleteObjectAndAddObject(t *testing.T) {
+	tests := []struct {
+		name string
+		id   uint32
+		opts []DeleteOpt
+	}{
+		{
+			name: "Compact",
+			id:   2,
+			opts: []DeleteOpt{
+				OptDeleteCompact(true),
+			},
+		},
+		{
+			name: "NoCompact",
+			id:   2,
+		},
+		{
+			name: "Zero",
+			id:   2,
+			opts: []DeleteOpt{
+				OptDeleteZero(true),
+			},
+		},
+		{
+			name: "ZeroCompact",
+			id:   2,
+			opts: []DeleteOpt{
+				OptDeleteZero(true),
+				OptDeleteCompact(true),
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var b Buffer
+
+			f, err := CreateContainer(&b,
+				OptCreateDeterministic(),
+				OptCreateWithDescriptors(
+					getDescriptorInput(t, DataGeneric, []byte("abc")),
+					getDescriptorInput(t, DataGeneric, []byte("def")),
+				),
+			)
+			if err != nil {
+				t.Fatal(err)
+			}
+
+			if err := f.DeleteObject(tt.id, tt.opts...); err != nil {
+				t.Fatal(err)
+			}
+
+			if err := f.AddObject(getDescriptorInput(t, DataGeneric, []byte("ghi"))); err != nil {
+				t.Fatal(err)
+			}
+
+			g := goldie.New(t, goldie.WithTestNameForDir(true))
+			g.Assert(t, tt.name, b.Bytes())
+		})
+	}
+}
+
 func TestSetPrimPart(t *testing.T) {
 	tests := []struct {
 		name       string