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Date: Sun, 19 Aug 2001 05:08:38 +0400
From: "Andrey A. Chernov" <ache@nagual.pp.ru>
To: Bruce Evans <bde@zeta.org.au>
Cc: arch@FreeBSD.ORG, current@FreeBSD.ORG
Subject: Re: CFR: lseek() POSIXed patch
Message-ID: <20010819050838.A86450@nagual.pp.ru>
References: <20010815125248.A2588@nagual.pp.ru> <20010815190108.J19482-100000@besplex.bde.org>
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Updated variant:

--- vfs_syscalls.c.old	Sat Aug 11 02:14:18 2001
+++ vfs_syscalls.c	Sun Aug 19 05:01:32 2001
@@ -1614,29 +1614,44 @@
 	register struct filedesc *fdp = p->p_fd;
 	register struct file *fp;
 	struct vattr vattr;
-	int error;
+	struct vnode *vp;
+	off_t offset;
+	int error, noneg;
 
 	if ((u_int)SCARG(uap, fd) >= fdp->fd_nfiles ||
 	    (fp = fdp->fd_ofiles[SCARG(uap, fd)]) == NULL)
 		return (EBADF);
 	if (fp->f_type != DTYPE_VNODE)
 		return (ESPIPE);
+	vp = (struct vnode *)fp->f_data;
+	noneg = (vp->v_type != VCHR);
+	offset = SCARG(uap, offset);
 	switch (SCARG(uap, whence)) {
 	case L_INCR:
-		fp->f_offset += SCARG(uap, offset);
+		if (noneg &&
+		    ((offset > 0 && fp->f_offset > OFF_MAX - offset) ||
+		     (offset < 0 && fp->f_offset < OFF_MIN - offset)))
+			return (EOVERFLOW);
+		offset += fp->f_offset;
 		break;
 	case L_XTND:
-		error=VOP_GETATTR((struct vnode *)fp->f_data, &vattr, cred, p);
+		error = VOP_GETATTR(vp, &vattr, cred, p);
 		if (error)
 			return (error);
-		fp->f_offset = SCARG(uap, offset) + vattr.va_size;
+		if (noneg &&
+		    ((offset > 0 && vattr.va_size > OFF_MAX - offset) ||
+		     (offset < 0 && vattr.va_size < OFF_MIN - offset)))
+			return (EOVERFLOW);
+		offset += vattr.va_size;
 		break;
 	case L_SET:
-		fp->f_offset = SCARG(uap, offset);
 		break;
 	default:
 		return (EINVAL);
 	}
+	if (noneg && offset < 0)
+		return (EINVAL);
+	fp->f_offset = offset;
 	*(off_t *)(p->p_retval) = fp->f_offset;
 	return (0);
 }

-- 
Andrey A. Chernov
http://ache.pp.ru/

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