Author: jhb
Date: Wed Mar 3 16:18:04 2010
New Revision: 204638
URL: http://svn.freebsd.org/changeset/base/204638
Log:
Allow lseek(SEEK_END) to work on disk devices by using the DIOCGMEDIASIZE
to determine the media size.
Submitted by: nox
MFC after: 1 week
Modified:
head/sys/kern/vfs_syscalls.c
Modified: head/sys/kern/vfs_syscalls.c
==============================================================================
--- head/sys/kern/vfs_syscalls.c Wed Mar 3 16:06:43 2010
(r204637)
+++ head/sys/kern/vfs_syscalls.c Wed Mar 3 16:18:04 2010
(r204638)
@@ -45,6 +45,7 @@ __FBSDID("$FreeBSD$");
#include <sys/systm.h>
#include <sys/bio.h>
#include <sys/buf.h>
+#include <sys/disk.h>
#include <sys/sysent.h>
#include <sys/malloc.h>
#include <sys/mount.h>
@@ -1920,7 +1921,7 @@ lseek(td, uap)
struct file *fp;
struct vnode *vp;
struct vattr vattr;
- off_t offset;
+ off_t offset, size;
int error, noneg;
int vfslocked;
@@ -1951,6 +1952,15 @@ lseek(td, uap)
VOP_UNLOCK(vp, 0);
if (error)
break;
+
+ /*
+ * If the file references a disk device, then fetch
+ * the media size and use that to determine the ending
+ * offset.
+ */
+ if (vattr.va_size == 0 && vp->v_type == VCHR &&
+ fo_ioctl(fp, DIOCGMEDIASIZE, &size, cred, td) == 0)
+ vattr.va_size = size;
if (noneg &&
(vattr.va_size > OFF_MAX ||
(offset > 0 && vattr.va_size > OFF_MAX - offset))) {
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