Rely on open event for .length property during reads

Author: nothingmuch

index.js

@@ -68,27 +68,25 @@ Store.prototype._read = function (offset, length, cb) {
   cb = once(cb)
   var buffers = []
   self._store('readonly', function (err, store) {
-    backify(store.get(self.name + DELIM + "length"), function(err, ev) {
-      if ((ev.target.result || 0) < offset+length) {
-        return cb(new Error('Could not satisfy length'))
-      }
-      if (err) return cb(err)
-      var offsets = self._blocks(offset, offset+length)
-      var pending = offsets.length + 1
-      var firstBlock = offsets.length > 0 ? offsets[0].block : 0
-      var j = 0
-      for (var i = 0; i < offsets.length; i++) (function (o) {
-        var key = self.name + DELIM + o.block
-        backify(store.get(key), function (err, ev) {
-          if (err) return cb(err)
-          buffers[o.block-firstBlock] = ev.target.result
-            ? bufferFrom(ev.target.result.subarray(o.start,o.end))
-            : bufferAlloc(o.end-o.start)
-          if (--pending === 0) cb(null, Buffer.concat(buffers))
-        })
-      })(offsets[i])
-      if (--pending === 0) cb(null, Buffer.concat(buffers))
-    })
+    if ((self.length || 0) < offset+length) {
+      return cb(new Error('Could not satisfy length'))
+    }
+    if (err) return cb(err)
+    var offsets = self._blocks(offset, offset+length)
+    var pending = offsets.length + 1
+    var firstBlock = offsets.length > 0 ? offsets[0].block : 0
+    var j = 0
+    for (var i = 0; i < offsets.length; i++) (function (o) {
+      var key = self.name + DELIM + o.block
+      backify(store.get(key), function (err, ev) {
+        if (err) return cb(err)
+        buffers[o.block-firstBlock] = ev.target.result
+          ? bufferFrom(ev.target.result.subarray(o.start,o.end))
+          : bufferAlloc(o.end-o.start)
+        if (--pending === 0) cb(null, Buffer.concat(buffers))
+      })
+    })(offsets[i])
+    if (--pending === 0) cb(null, Buffer.concat(buffers))
   })
 }