feat: allow specify hash algorithm for large files (#184)

Author: alanshaw

README.md

@@ -115,7 +115,7 @@ The `import` object is a duplex pull stream that takes objects of the form:
 }
 ```
 
-`import` will outoyt file info objects as files get stored in IPFS. When stats on a node are emitted they are guaranteed to have been written.
+`import` will output file info objects as files get stored in IPFS. When stats on a node are emitted they are guaranteed to have been written.
 
 `dag` is an instance of the [`IPLD Resolver`](https://github.com/ipld/js-ipld-resolver) or the [`js-ipfs` `dag api`](https://github.com/ipfs/interface-ipfs-core/tree/master/API/dag)
 
@@ -140,6 +140,7 @@ The input's file paths and directory structure will be preserved in the [`dag-pb
     - bits (positive integer, defaults to `8`): the number of bits at each bucket of the HAMT
 - `progress` (function): a function that will be called with the byte length of chunks as a file is added to ipfs.
 - `onlyHash` (boolean, defaults to false): Only chunk and hash - do not write to disk
+- `hashAlg` (string): multihash hashing algorithm to use
 
 ### Exporter
 

src/builder/reduce.js

@@ -32,7 +32,7 @@ module.exports = function (file, ipldResolver, options) {
     })
 
     waterfall([
-      (cb) => DAGNode.create(f.marshal(), links, cb),
+      (cb) => DAGNode.create(f.marshal(), links, options.hashAlg, cb),
       (node, cb) => {
         if (options.onlyHash) return cb(null, node)
 

src/importer/dir-flat.js

@@ -56,12 +56,13 @@ class DirFlat extends Dir {
       })
 
     const dir = new UnixFS('directory')
+    const options = this._options
 
     waterfall(
       [
-        (callback) => DAGNode.create(dir.marshal(), links, callback),
+        (callback) => DAGNode.create(dir.marshal(), links, options.hashAlg, callback),
         (node, callback) => {
-          if (this._options.onlyHash) return callback(null, node)
+          if (options.onlyHash) return callback(null, node)
 
           ipldResolver.put(
             node,

src/importer/dir-sharded.js

@@ -144,7 +144,7 @@ function flush (options, bucket, path, ipldResolver, source, callback) {
     dir.hashType = options.hashFn.code
     waterfall(
       [
-        (callback) => DAGNode.create(dir.marshal(), links, callback),
+        (callback) => DAGNode.create(dir.marshal(), links, options.hashAlg, callback),
         (node, callback) => {
           if (options.onlyHash) return callback(null, node)
 

test/test-builder.js

@@ -57,5 +57,38 @@ module.exports = (repo) => {
         )
       }, done)
     })
+
+    it('allows multihash hash algorithm to be specified for big file', (done) => {
+      eachSeries(Object.keys(mh.names), (hashAlg, cb) => {
+        const options = { hashAlg, strategy: 'flat' }
+        const content = String(Math.random() + Date.now())
+        const inputFile = {
+          path: content + '.txt',
+          // Bigger than maxChunkSize
+          content: Buffer.alloc(262144 + 5).fill(1)
+        }
+
+        const onCollected = (err, nodes) => {
+          if (err) return cb(err)
+
+          const node = nodes[0]
+
+          try {
+            expect(node).to.exist()
+            expect(mh.decode(node.multihash).name).to.equal(hashAlg)
+          } catch (err) {
+            return cb(err)
+          }
+
+          cb()
+        }
+
+        pull(
+          pull.values([Object.assign({}, inputFile)]),
+          createBuilder(FixedSizeChunker, ipldResolver, options),
+          pull.collect(onCollected)
+        )
+      }, done)
+    })
   })
 }