Merge branch 'fix-crash'

node.go

@@ -221,11 +221,20 @@ func (n *node) write(p *page) {
 			_assert(elem.pgid != p.id, "write: circular dependency occurred")
 		}
 
+		// If the length of key+value is larger than the max allocation size
+		// then we need to reallocate the byte array pointer.
+		//
+		// See: https://github.com/boltdb/bolt/pull/335
+		klen, vlen := len(item.key), len(item.value)
+		if len(b) < klen+vlen {
+			b = (*[maxAllocSize]byte)(unsafe.Pointer(&b[0]))[:]
+		}
+
 		// Write data for the element to the end of the page.
 		copy(b[0:], item.key)
-		b = b[len(item.key):]
+		b = b[klen:]
 		copy(b[0:], item.value)
-		b = b[len(item.value):]
+		b = b[vlen:]
 	}
 
 	// DEBUG ONLY: n.dump()

page.go

@@ -96,7 +96,7 @@ type branchPageElement struct {
 // key returns a byte slice of the node key.
 func (n *branchPageElement) key() []byte {
 	buf := (*[maxAllocSize]byte)(unsafe.Pointer(n))
-	return buf[n.pos : n.pos+n.ksize]
+	return (*[maxAllocSize]byte)(unsafe.Pointer(&buf[n.pos]))[:n.ksize]
 }
 
 // leafPageElement represents a node on a leaf page.
@@ -110,13 +110,13 @@ type leafPageElement struct {
 // key returns a byte slice of the node key.
 func (n *leafPageElement) key() []byte {
 	buf := (*[maxAllocSize]byte)(unsafe.Pointer(n))
-	return buf[n.pos : n.pos+n.ksize]
+	return (*[maxAllocSize]byte)(unsafe.Pointer(&buf[n.pos]))[:n.ksize]
 }
 
 // value returns a byte slice of the node value.
 func (n *leafPageElement) value() []byte {
 	buf := (*[maxAllocSize]byte)(unsafe.Pointer(n))
-	return buf[n.pos+n.ksize : n.pos+n.ksize+n.vsize]
+	return (*[maxAllocSize]byte)(unsafe.Pointer(&buf[n.pos+n.ksize]))[:n.vsize]
 }
 
 // PageInfo represents human readable information about a page.

tx.go

@@ -423,15 +423,39 @@ func (tx *Tx) write() error {
 	// Write pages to disk in order.
 	for _, p := range pages {
 		size := (int(p.overflow) + 1) * tx.db.pageSize
-		buf := (*[maxAllocSize]byte)(unsafe.Pointer(p))[:size]
 		offset := int64(p.id) * int64(tx.db.pageSize)
-		if _, err := tx.db.ops.writeAt(buf, offset); err != nil {
-			return err
-		}
 
-		// Update statistics.
-		tx.stats.Write++
+		// Write out page in "max allocation" sized chunks.
+		ptr := (*[maxAllocSize]byte)(unsafe.Pointer(p))
+		for {
+			// Limit our write to our max allocation size.
+			sz := size
+			if sz > maxAllocSize-1 {
+				sz = maxAllocSize - 1
+			}
+
+			// Write chunk to disk.
+			buf := ptr[:sz]
+			if _, err := tx.db.ops.writeAt(buf, offset); err != nil {
+				return err
+			}
+
+			// Update statistics.
+			tx.stats.Write++
+
+			// Exit inner for loop if we've written all the chunks.
+			size -= sz
+			if size == 0 {
+				break
+			}
+
+			// Otherwise move offset forward and move pointer to next chunk.
+			offset += int64(sz)
+			ptr = (*[maxAllocSize]byte)(unsafe.Pointer(&ptr[sz]))
+		}
 	}
+
+	// Ignore file sync if flag is set on DB.
 	if !tx.db.NoSync || IgnoreNoSync {
 		if err := fdatasync(tx.db); err != nil {
 			return err