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Date:      Fri, 6 Jan 2012 10:12:59 +0000 (UTC)
From:      Jaakko Heinonen <jh@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r229694 - head/sys/fs/pseudofs
Message-ID:  <201201061012.q06ACxxw082682@svn.freebsd.org>
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Author: jh
Date: Fri Jan  6 10:12:59 2012
New Revision: 229694
URL: http://svn.freebsd.org/changeset/base/229694

Log:
  r222004 changed sbuf_finish() to not clear the buffer error status. As a
  consequence sbuf_len() will return -1 for buffers which had the error
  status set prior to sbuf_finish() call. This causes a problem in
  pfs_read() which purposely uses a fixed size sbuf to discard bytes which
  are not needed to fulfill the read request.
  
  Work around the problem by using the full buffer length when
  sbuf_finish() indicates an overflow. An overflowed sbuf with fixed size
  is always full.
  
  PR:		kern/163076
  Approved by:	des
  MFC after:	2 weeks

Modified:
  head/sys/fs/pseudofs/pseudofs_vnops.c

Modified: head/sys/fs/pseudofs/pseudofs_vnops.c
==============================================================================
--- head/sys/fs/pseudofs/pseudofs_vnops.c	Fri Jan  6 09:21:40 2012	(r229693)
+++ head/sys/fs/pseudofs/pseudofs_vnops.c	Fri Jan  6 10:12:59 2012	(r229694)
@@ -630,14 +630,14 @@ pfs_read(struct vop_read_args *va)
 	if (uio->uio_offset < 0 || uio->uio_resid < 0 ||
 	    (offset = uio->uio_offset) != uio->uio_offset ||
 	    (resid = uio->uio_resid) != uio->uio_resid ||
-	    (buflen = offset + resid + 1) < offset || buflen > INT_MAX) {
+	    (buflen = offset + resid) < offset || buflen >= INT_MAX) {
 		error = EINVAL;
 		goto ret;
 	}
-	if (buflen > MAXPHYS + 1)
-		buflen = MAXPHYS + 1;
+	if (buflen > MAXPHYS)
+		buflen = MAXPHYS;
 
-	sb = sbuf_new(sb, NULL, buflen, 0);
+	sb = sbuf_new(sb, NULL, buflen + 1, 0);
 	if (sb == NULL) {
 		error = EIO;
 		goto ret;
@@ -650,8 +650,14 @@ pfs_read(struct vop_read_args *va)
 		goto ret;
 	}
 
-	sbuf_finish(sb);
-	error = uiomove_frombuf(sbuf_data(sb), sbuf_len(sb), uio);
+	/*
+	 * XXX: If the buffer overflowed, sbuf_len() will not return
+	 * the data length. Then just use the full length because an
+	 * overflowed sbuf must be full.
+	 */
+	if (sbuf_finish(sb) == 0)
+		buflen = sbuf_len(sb);
+	error = uiomove_frombuf(sbuf_data(sb), buflen, uio);
 	sbuf_delete(sb);
 ret:
 	vn_lock(vn, locked | LK_RETRY);

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