Date: Thu, 4 Mar 1999 17:10:01 -0800 (PST) From: John Plevyak <jplevyak@inktomi.com> To: freebsd-bugs@FreeBSD.org Subject: Re: kern/8011: libc_r does not have pread() or pwrite() interfaces Message-ID: <199903050110.RAA49007@freefall.freebsd.org>
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The following reply was made to PR kern/8011; it has been noted by GNATS.
From: John Plevyak <jplevyak@inktomi.com>
To: freebsd-gnats-submit@freebsd.org, info@highwind.com
Cc:
Subject: Re: kern/8011: libc_r does not have pread() or pwrite() interfaces
Date: Fri, 05 Mar 1999 01:09:12 +0000
pread and pwrite under FreeBSD 3.1+ also require patching vfs_vnops.c
because
vn_read/vn_write mess with fp->f_offset as well:
Index: sys/kern/vfs_vnops.c
===================================================================
RCS file: /usr/cvsroot/src/sys/kern/vfs_vnops.c,v
retrieving revision 1.62
diff -c -r1.62 vfs_vnops.c
*** vfs_vnops.c 1999/01/20 14:49:11 1.62
--- vfs_vnops.c 1999/03/04 16:09:40
***************
*** 284,296 ****
VOP_LEASE(vp, p, cred, LEASE_READ);
vn_lock(vp, LK_SHARED | LK_NOPAUSE | LK_RETRY, p);
! if (uio->uio_offset == -1)
! uio->uio_offset = fp->f_offset;
! count = uio->uio_resid;
flag = 0;
if (fp->f_flag & FNONBLOCK)
flag |= IO_NDELAY;
/*
* Sequential read heuristic.
* If we have been doing sequential input,
--- 284,306 ----
VOP_LEASE(vp, p, cred, LEASE_READ);
vn_lock(vp, LK_SHARED | LK_NOPAUSE | LK_RETRY, p);
!
flag = 0;
if (fp->f_flag & FNONBLOCK)
flag |= IO_NDELAY;
+ if (uio->uio_offset != -1) {
+ flag = 0;
+ if (fp->f_flag & FNONBLOCK)
+ flag |= IO_NDELAY;
+ error = VOP_READ(vp, uio, flag, cred);
+ VOP_UNLOCK(vp, 0, p);
+ return error;
+ }
+
+ uio->uio_offset = fp->f_offset;
+ count = uio->uio_resid;
+
/*
* Sequential read heuristic.
* If we have been doing sequential input,
***************
*** 347,352 ****
--- 357,367 ----
ioflag |= IO_SYNC;
VOP_LEASE(vp, p, cred, LEASE_WRITE);
vn_lock(vp, LK_EXCLUSIVE | LK_RETRY, p);
+ if (uio->uio_offset != -1) {
+ error = VOP_WRITE(vp, uio, ioflag, cred);
+ VOP_UNLOCK(vp, 0, p);
+ return error;
+ }
uio->uio_offset = fp->f_offset;
count = uio->uio_resid;
error = VOP_WRITE(vp, uio, ioflag, cred);
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