readi: Fix sign handling problems

We are permitted to write from beyond EOF, but a read from beyond EOF must
return 0

diff --git a/Kernel/inode.c b/Kernel/inode.c
index c7c3b57..d7bfabb 100644 (file)
--- a/Kernel/inode.c
+++ b/Kernel/inode.c
@@ -26,9 +26,12 @@ void readi(inoptr ino, uint8_t flag)
        case F_REG:
 
                /* See if end of file will limit read */
-
-               udata.u_count = min(udata.u_count,
+               if (ino->c_node.i_size <= udata.u_offset)
+                       udata.u_count = 0;
+                else {
+                       udata.u_count = min(udata.u_count,
                                ino->c_node.i_size - udata.u_offset);
+                }
                toread = udata.u_count;
                goto loop;