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Allow lseek(SEEK_END) to work on disk devices by using the DIOCGMEDIASIZE

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to determine the media size.

Submitted by:	nox
MFC after:	1 week
This commit is contained in:
John Baldwin 2010-03-03 16:18:04 +00:00
parent 967e82cae0
commit ab99e589dd
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=204638
1 changed files with 11 additions and 1 deletions
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12
sys/kern/vfs_syscalls.c
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@ -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))) {