From: David van Moolenbroek <david@minix3.org>
Date: Wed, 28 Aug 2013 11:08:16 +0000 (+0200)
Subject: VFS: fix interruption of blocking pipe operations
X-Git-Tag: v3.3.0~604
X-Git-Url: http://zhaoyanbai.com/repos/?a=commitdiff_plain;h=1e7b45c682c73790e20ea992ff153bef5ac8f0fc;p=minix.git

VFS: fix interruption of blocking pipe operations

POSIX states that when interrupted, partially successful pipe
operations should return the partial result rather than EINTR. VFS
previously wouldn't look at the partial result, and not clear it
either, which would result in a panic upon the next pipe operation.

Change-Id: Ia1eb72b4b77394051444e63a1390d49bb315eb04
---

diff --git a/servers/vfs/pipe.c b/servers/vfs/pipe.c
index 83cc7fe66..57c2378b8 100644
--- a/servers/vfs/pipe.c
+++ b/servers/vfs/pipe.c
@@ -548,6 +548,15 @@ void unpause(void)
 
   switch (blocked_on) {
 	case FP_BLOCKED_ON_PIPE:/* process trying to read or write a pipe */
+		/* If the operation succeeded partially, return the bytes
+		 * processed so far, and clear the remembered state. Otherwise,
+		 * return EINTR as usual.
+		 */
+		if (fp->fp_cum_io_partial > 0) {
+			status = fp->fp_cum_io_partial;
+
+			fp->fp_cum_io_partial = 0;
+		}
 		break;
 
 	case FP_BLOCKED_ON_LOCK:/* process trying to set a lock with FCNTL */