azureblob: remove uncommitted blocks on InvalidBlobOrBlock error

When doing a multipart upload or copy, if a InvalidBlobOrBlock error
is received, it can mean that there are uncomitted blocks from a
previous failed attempt with a different length of ID.

This patch makes rclone attempt to clear the uncomitted blocks and
retry if it receives this error.

backend/azureblob/azureblob_internal_test.go

@@ -3,22 +3,20 @@
 package azureblob
 
 import (
+	"context"
 	"encoding/base64"
+	"strings"
 	"testing"
 
+	"github.com/Azure/azure-sdk-for-go/sdk/storage/azblob/blockblob"
+	"github.com/rclone/rclone/fs"
+	"github.com/rclone/rclone/fstest"
+	"github.com/rclone/rclone/fstest/fstests"
+	"github.com/rclone/rclone/lib/random"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
-func (f *Fs) InternalTest(t *testing.T) {
-	// Check first feature flags are set on this
-	// remote
-	enabled := f.Features().SetTier
-	assert.True(t, enabled)
-	enabled = f.Features().GetTier
-	assert.True(t, enabled)
-}
-
 func TestBlockIDCreator(t *testing.T) {
 	// Check creation and random number
 	bic, err := newBlockIDCreator()
@@ -46,3 +44,108 @@ func TestBlockIDCreator(t *testing.T) {
 	assert.ErrorContains(t, bic.checkID(chunkNumber+1, got), "expecting decoded")
 	assert.ErrorContains(t, bic2.checkID(chunkNumber, got), "random bytes")
 }
+
+func (f *Fs) testFeatures(t *testing.T) {
+	// Check first feature flags are set on this remote
+	enabled := f.Features().SetTier
+	assert.True(t, enabled)
+	enabled = f.Features().GetTier
+	assert.True(t, enabled)
+}
+
+type ReadSeekCloser struct {
+	*strings.Reader
+}
+
+func (r *ReadSeekCloser) Close() error {
+	return nil
+}
+
+// Stage a block at remote but don't commit it
+func (f *Fs) stageBlockWithoutCommit(ctx context.Context, t *testing.T, remote string) {
+	var (
+		containerName, blobPath = f.split(remote)
+		containerClient         = f.cntSVC(containerName)
+		blobClient              = containerClient.NewBlockBlobClient(blobPath)
+		data                    = "uncommitted data"
+		blockID                 = "1"
+		blockIDBase64           = base64.StdEncoding.EncodeToString([]byte(blockID))
+	)
+	r := &ReadSeekCloser{strings.NewReader(data)}
+	_, err := blobClient.StageBlock(ctx, blockIDBase64, r, nil)
+	require.NoError(t, err)
+
+	// Verify the block is staged but not committed
+	blockList, err := blobClient.GetBlockList(ctx, blockblob.BlockListTypeAll, nil)
+	require.NoError(t, err)
+	found := false
+	for _, block := range blockList.UncommittedBlocks {
+		if *block.Name == blockIDBase64 {
+			found = true
+			break
+		}
+	}
+	require.True(t, found, "Block ID not found in uncommitted blocks")
+}
+
+// This tests uploading a blob where it has uncommitted blocks with a different ID size.
+//
+// https://gauravmantri.com/2013/05/18/windows-azure-blob-storage-dealing-with-the-specified-blob-or-block-content-is-invalid-error/
+//
+// TestIntegration/FsMkdir/FsPutFiles/Internal/WriteUncommittedBlocks
+func (f *Fs) testWriteUncommittedBlocks(t *testing.T) {
+	var (
+		ctx    = context.Background()
+		remote = "testBlob"
+	)
+
+	// Multipart copy the blob please
+	oldUseCopyBlob, oldCopyCutoff := f.opt.UseCopyBlob, f.opt.CopyCutoff
+	f.opt.UseCopyBlob = false
+	f.opt.CopyCutoff = f.opt.ChunkSize
+	defer func() {
+		f.opt.UseCopyBlob, f.opt.CopyCutoff = oldUseCopyBlob, oldCopyCutoff
+	}()
+
+	// Create a blob with uncommitted blocks
+	f.stageBlockWithoutCommit(ctx, t, remote)
+
+	// Now attempt to overwrite the block with a different sized block ID to provoke this error
+
+	// Check the object does not exist
+	_, err := f.NewObject(ctx, remote)
+	require.Equal(t, fs.ErrorObjectNotFound, err)
+
+	// Upload a multipart file over the block with uncommitted chunks of a different ID size
+	size := 4*int(f.opt.ChunkSize) - 1
+	contents := random.String(size)
+	item := fstest.NewItem(remote, contents, fstest.Time("2001-05-06T04:05:06.499Z"))
+	o := fstests.PutTestContents(ctx, t, f, &item, contents, true)
+
+	// Check size
+	assert.Equal(t, int64(size), o.Size())
+
+	// Create a new blob with uncommitted blocks
+	newRemote := "testBlob2"
+	f.stageBlockWithoutCommit(ctx, t, newRemote)
+
+	// Copy over that block
+	dst, err := f.Copy(ctx, o, newRemote)
+	require.NoError(t, err)
+
+	// Check basics
+	assert.Equal(t, int64(size), dst.Size())
+	assert.Equal(t, newRemote, dst.Remote())
+
+	// Check contents
+	gotContents := fstests.ReadObject(ctx, t, dst, -1)
+	assert.Equal(t, contents, gotContents)
+
+	// Remove the object
+	require.NoError(t, dst.Remove(ctx))
+}
+
+func (f *Fs) InternalTest(t *testing.T) {
+	t.Run("Features", f.testFeatures)
+	t.Run("WriteUncommittedBlocks", f.testWriteUncommittedBlocks)
+}