Comment read.go.

fuse/read.go

@@ -5,8 +5,18 @@ import (
 	"syscall"
 )
 
+// The result of Read is an array of bytes, but for performance
+// reasons, we can also return data as a file-descriptor/offset/size
+// tuple.  If the backing store for the file system is another
+// filesystem, this reduces the amount of copying and memory in use.
+//
+// If at any point,  the raw data is needed, ReadResult.Read() will
+// load the raw data. 
 type ReadResult struct {
+	// Errno code for the read.
 	Status
+
+	// Raw bytes for the read.
 	Data []byte
 
 	// If Data is nil and Status OK, splice from the following
@@ -15,6 +25,9 @@ type ReadResult struct {
 
 	// Offset within Fd, or -1 to use current offset.
 	FdOff  int64
+
+	// Size of data to be loaded. Actual data available may be
+	// less at the EOF.
 	FdSize int
 }
 
@@ -29,6 +42,8 @@ func (r *ReadResult) Size() int {
 	return r.FdSize
 }
 
+// Reads raw bytes from file descriptor if necessary, using the passed
+// buffer as storage.
 func (r *ReadResult) Read(buf []byte) Status {
 	if r.Data != nil || !r.Ok() {
 		return r.Status