[PXEXT] Avoid queueing zero-length buffers in posix_io.c

read_user() assumes that zero-length buffers don't exist, and optimises
around this.

diff --git a/src/core/posix_io.c b/src/core/posix_io.c
index b48c1f80c8cdfa7ac6596c757e6cbbe0d57364a8..e0459bdf199edaf0ae83e3c75fbac52109c685dc 100644 (file)
--- a/src/core/posix_io.c
+++ b/src/core/posix_io.c
@@ -114,7 +114,7 @@ static void posix_file_xfer_close ( struct xfer_interface *xfer, int rc ) {
 static int
 posix_file_xfer_deliver_iob ( struct xfer_interface *xfer,
                              struct io_buffer *iobuf,
-                             struct xfer_metadata *meta __unused ) {
+                             struct xfer_metadata *meta ) {
        struct posix_file *file =
                container_of ( xfer, struct posix_file, xfer );
 
@@ -125,7 +125,12 @@ posix_file_xfer_deliver_iob ( struct xfer_interface *xfer,
        if ( file->filesize < file->pos )
                file->filesize = file->pos;
 
-       list_add_tail ( &iobuf->list, &file->data );
+       if ( iob_len ( iobuf ) ) {
+               list_add_tail ( &iobuf->list, &file->data );
+       } else {
+               free_iob ( iobuf );
+       }
+
        return 0;
 }
 
@@ -293,14 +298,15 @@ ssize_t read_user ( int fd, userptr_t buffer, off_t offset, size_t max_len ) {
                        free_iob ( iobuf );
                }
                file->pos += len;
-               if ( len )
-                       return len;
-               break;
+               assert ( len != 0 );
+               return len;
        }
 
        /* If file has completed, return (after returning all data) */
-       if ( file->rc != -EINPROGRESS )
+       if ( file->rc != -EINPROGRESS ) {
+               assert ( list_empty ( &file->data ) );
                return file->rc;
+       }
 
        /* No data ready and file still in progress; return -WOULDBLOCK */
        return -EWOULDBLOCK;