Module Name: src
Committed By: manu
Date: Thu Jan 31 02:27:06 UTC 2019
Modified Files:
src/sys/kern: vfs_syscalls.c
Log Message:
Do not resolve fdat for openat(2) if path is absolute
Opengroup says "The openat() function shall be equivalent to the open()
function except in the case where path specifies a relative path", but
says nothing about fdat usage when path is absolute;
https://pubs.opengroup.org/onlinepubs/9699919799/functions/open.html
We used to always reslove fdat, leading to error if it was invalid (e.g.: -1).
That caused portability problem with other systems that
just ignore it. See discussion in a pull request to work around that
problem with MariaDB: https://github.com/MariaDB/server/pull/838
We fix the problem by ignoring fdat when path is absolute.
To generate a diff of this commit:
cvs rdiff -u -r1.520 -r1.521 src/sys/kern/vfs_syscalls.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/kern/vfs_syscalls.c
diff -u src/sys/kern/vfs_syscalls.c:1.520 src/sys/kern/vfs_syscalls.c:1.521
--- src/sys/kern/vfs_syscalls.c:1.520 Tue Jan 29 09:28:50 2019
+++ src/sys/kern/vfs_syscalls.c Thu Jan 31 02:27:06 2019
@@ -1,4 +1,4 @@
-/* $NetBSD: vfs_syscalls.c,v 1.520 2019/01/29 09:28:50 pgoyette Exp $ */
+/* $NetBSD: vfs_syscalls.c,v 1.521 2019/01/31 02:27:06 manu Exp $ */
/*-
* Copyright (c) 2008, 2009 The NetBSD Foundation, Inc.
@@ -70,7 +70,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: vfs_syscalls.c,v 1.520 2019/01/29 09:28:50 pgoyette Exp $");
+__KERNEL_RCSID(0, "$NetBSD: vfs_syscalls.c,v 1.521 2019/01/31 02:27:06 manu Exp $");
#ifdef _KERNEL_OPT
#include "opt_fileassoc.h"
@@ -1631,6 +1631,7 @@ do_sys_openat(lwp_t *l, int fdat, const
file_t *dfp = NULL;
struct vnode *dvp = NULL;
struct pathbuf *pb;
+ const char *pathstring = NULL;
int error;
if (path == NULL) {
@@ -1643,7 +1644,14 @@ do_sys_openat(lwp_t *l, int fdat, const
return error;
}
- if (fdat != AT_FDCWD) {
+ pathstring = pathbuf_stringcopy_get(pb);
+
+ /*
+ * fdat is ignored if:
+ * 1) if fdat is AT_FDCWD, which means use current directory as base.
+ * 2) if path is absolute, then fdat is useless.
+ */
+ if (fdat != AT_FDCWD && pathstring[0] != '/') {
/* fd_getvnode() will use the descriptor for us */
if ((error = fd_getvnode(fdat, &dfp)) != 0)
goto out;
@@ -1656,6 +1664,7 @@ do_sys_openat(lwp_t *l, int fdat, const
if (dfp != NULL)
fd_putfile(fdat);
out:
+ pathbuf_stringcopy_put(pb, pathstring);
pathbuf_destroy(pb);
return error;
}
