From b176dd8a27e298daa28151a55c48c0263dd1c4e4 Mon Sep 17 00:00:00 2001
From: Keenan Nemetz <keenan.nemetz@gmail.com>
Date: Fri, 29 Jan 2021 14:18:42 -0800
Subject: [PATCH] Export unixfs chunk function.

---
 unixfs/add.go   | 47 +++++++++++------------------------------------
 unixfs/chunk.go | 45 +++++++++++++++++++++++++++++++++++++++++++++
 unixfs/merge.go |  2 +-
 3 files changed, 57 insertions(+), 37 deletions(-)
 create mode 100644 unixfs/chunk.go

diff --git a/unixfs/add.go b/unixfs/add.go
index 8cf42e8..c1b077a 100644
--- a/unixfs/add.go
+++ b/unixfs/add.go
@@ -3,23 +3,16 @@ package unixfs
 import (
 	"context"
 	"errors"
-	"io"
 	"io/ioutil"
 	"os"
 	"path/filepath"
 
-	"github.com/ipfs/go-ipfs-chunker"
 	ipld "github.com/ipfs/go-ipld-format"
 	"github.com/ipfs/go-merkledag"
 	ufs "github.com/ipfs/go-unixfs"
-	"github.com/ipfs/go-unixfs/importer/balanced"
-	"github.com/ipfs/go-unixfs/importer/helpers"
 	ufsio "github.com/ipfs/go-unixfs/io"
 )
 
-// DefaultChunker is the name of the default chunker algorithm.
-const DefaultChunker = "buzhash"
-
 // Ignore is used to filter files.
 type Ignore []string
 
@@ -58,32 +51,6 @@ func Add(ctx context.Context, dag ipld.DAGService, path string, ignore Ignore) (
 	}
 }
 
-// addReader splits the given reader into chunks and arranges them into a dag node.
-func addReader(ctx context.Context, dag ipld.DAGService, reader io.Reader) (ipld.Node, error) {
-	chunker, err := chunk.FromString(reader, DefaultChunker)
-	if err != nil {
-		return nil, err
-	}
-
-	params := helpers.DagBuilderParams{
-		Dagserv:    dag,
-		CidBuilder: merkledag.V1CidPrefix(),
-		Maxlinks:   helpers.DefaultLinksPerBlock,
-	}
-
-	helper, err := params.New(chunker)
-	if err != nil {
-		return nil, err
-	}
-
-	node, err := balanced.Layout(helper)
-	if err != nil {
-		return nil, err
-	}
-
-	return node, dag.Add(ctx, node)
-}
-
 // addFile creates a dag node from the file at the given path.
 func addFile(ctx context.Context, dag ipld.DAGService, path string) (ipld.Node, error) {
 	file, err := os.Open(path)
@@ -92,7 +59,7 @@ func addFile(ctx context.Context, dag ipld.DAGService, path string) (ipld.Node,
 	}
 	defer file.Close()
 
-	return addReader(ctx, dag, file)
+	return Chunk(ctx, dag, file)
 }
 
 // addSymlink creates a dag node from the symlink at the given path.
@@ -108,7 +75,11 @@ func addSymlink(ctx context.Context, dag ipld.DAGService, path string) (ipld.Nod
 	}
 
 	node := merkledag.NodeWithData(data)
-	return node, dag.Add(ctx, node)
+	if err := dag.Add(ctx, node); err != nil {
+		return nil, err
+	}
+
+	return node, nil
 }
 
 // addDir creates a dag node from the directory entries at the given path.
@@ -140,5 +111,9 @@ func addDir(ctx context.Context, dag ipld.DAGService, path string, ignore Ignore
 		return nil, err
 	}
 
-	return node, dag.Add(ctx, node)
+	if err := dag.Add(ctx, node); err != nil {
+		return nil, err
+	}
+
+	return node, nil
 }
diff --git a/unixfs/chunk.go b/unixfs/chunk.go
new file mode 100644
index 0000000..587c68c
--- /dev/null
+++ b/unixfs/chunk.go
@@ -0,0 +1,45 @@
+package unixfs
+
+import (
+	"context"
+	"io"
+
+	chunk "github.com/ipfs/go-ipfs-chunker"
+	ipld "github.com/ipfs/go-ipld-format"
+	"github.com/ipfs/go-merkledag"
+	"github.com/ipfs/go-unixfs/importer/balanced"
+	"github.com/ipfs/go-unixfs/importer/helpers"
+)
+
+// DefaultChunker is the name of the default chunker algorithm.
+const DefaultChunker = "buzhash"
+
+// Chunk splits the given reader into chunks and arranges them into a dag node.
+func Chunk(ctx context.Context, dag ipld.DAGService, reader io.Reader) (ipld.Node, error) {
+	chunker, err := chunk.FromString(reader, DefaultChunker)
+	if err != nil {
+		return nil, err
+	}
+
+	params := helpers.DagBuilderParams{
+		Dagserv:    dag,
+		CidBuilder: merkledag.V1CidPrefix(),
+		Maxlinks:   helpers.DefaultLinksPerBlock,
+	}
+
+	helper, err := params.New(chunker)
+	if err != nil {
+		return nil, err
+	}
+
+	node, err := balanced.Layout(helper)
+	if err != nil {
+		return nil, err
+	}
+
+	if err := dag.Add(ctx, node); err != nil {
+		return nil, err
+	}
+
+	return node, nil
+}
diff --git a/unixfs/merge.go b/unixfs/merge.go
index 4d99a35..c5e8e65 100644
--- a/unixfs/merge.go
+++ b/unixfs/merge.go
@@ -29,5 +29,5 @@ func Merge(ctx context.Context, dag ipld.DAGService, o, a, b cid.Cid) (ipld.Node
 	merged := diff3.Merge(textO, textA, textB)
 	reader := strings.NewReader(merged)
 
-	return addReader(ctx, dag, reader)
+	return Chunk(ctx, dag, reader)
 }