[src/trunk]: src/sys/kern Update the uio resid counts appropriately when any ...

[jdolecek <jdolecek%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/88cee7d382cf
branches:  trunk
changeset: 515594:88cee7d382cf
user:      jdolecek <jdolecek%NetBSD.org@localhost>
date:      Sat Sep 29 13:48:11 2001 +0000

description:
Update the uio resid counts appropriately when any error occurs
(not just EPIPE), so that the higher-level code would note partial
write has happened and DTRT if the write was interrupted due to
e.g. delivery of signal.

This fixes kern/14087 by Frank van der Linden.
Much thanks to Frank for extensive help with debugging this, and review
of the fix.

Note: EPIPE/SIGPIPE delivery behaviour was retained - they're delivered
even if the write was partially successful.

diffstat:

 sys/kern/sys_pipe.c |  25 ++++++++++++-------------
 1 files changed, 12 insertions(+), 13 deletions(-)

diffs (52 lines):

diff -r 19d10f9a4698 -r 88cee7d382cf sys/kern/sys_pipe.c
--- a/sys/kern/sys_pipe.c       Sat Sep 29 13:05:46 2001 +0000
+++ b/sys/kern/sys_pipe.c       Sat Sep 29 13:48:11 2001 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: sys_pipe.c,v 1.14 2001/09/25 19:01:21 jdolecek Exp $   */
+/*     $NetBSD: sys_pipe.c,v 1.15 2001/09/29 13:48:11 jdolecek Exp $   */
 
 /*
  * Copyright (c) 1996 John S. Dyson
@@ -1086,23 +1086,22 @@
                pipe_loan_free(wpipe);
        pipeunlock(wpipe);
 
-       if (error == EPIPE) {
+       if (error) {
                pipeselwakeup(wpipe, wpipe);
 
                /*
-                * If anything was read from what we offered, return success
-                * and short write. We return EOF on next write(2).
+                * If nothing was read from what we offered, return error
+                * streight on. Otherwise update uio resid first. Caller
+                * will deal with the error condition, returning short
+                * write, error, or restarting the write(2) as appropriate.
                 */
-               if (wpipe->pipe_map.cnt < bcnt) {
-                       bcnt -= wpipe->pipe_map.cnt;
-                       error = 0;
+               if (wpipe->pipe_map.cnt == bcnt) {
+   error:
+                       wakeup(wpipe);
+                       return (error);
                }
-       }
 
-       if (error) {
-   error:
-               wakeup(wpipe);
-               return (error);
+               bcnt -= wpipe->pipe_map.cnt;
        }
 
        uio->uio_resid  -= bcnt;
@@ -1114,7 +1113,7 @@
                uio->uio_iovcnt--;
        }
 
-       return (0);
+       return (error);
 }
 #endif /* !PIPE_NODIRECT */
 #endif /* NetBSD */