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[PATCH 2/6] New internal function __access_noerrno
- From: Siddhesh Poyarekar <siddhesh at sourceware dot org>
- To: libc-alpha at sourceware dot org
- Date: Mon, 24 Oct 2016 20:12:44 +0530
- Subject: [PATCH 2/6] New internal function __access_noerrno
- Authentication-results: sourceware.org; auth=none
- References: <1477320168-23397-1-git-send-email-siddhesh@sourceware.org>
Implement an internal version of __access called __access_noerrno that
avoids setting errno. This is useful to check accessibility of files
very early on in process startup i.e. before TLS setup. This allows
tunables to replace MALLOC_CHECK_ safely (i.e. check existence of
/etc/suid-debug to enable/disable MALLOC_CHECK) and at the same time
initialize very early so that it can override IFUNCs.
* include/unistd.h [IS_IN (rtld) || !defined SHARED]: Declare
__access_noerrno.
* io/Makefile (routines): Add access_noerrno.
* io/access.c (__ACCESS)[!__ACCESS]: Define as __access.
(__access): Rename to __ACCESS.
[!NOERRNO]: Retain default __access logic.
* io/access_noerrno.c: New file.
* sysdeps/mach/hurd/access.c (__ACCESS)[!__ACCESS]: Define as
__access.
(__HURD_FAIL): New macro.
(__access): Rename to __ACCESS. Use __HURD_FAIL instead of
__hurd_fail.
[!NOERRNO]: Set weak alias to access.
* sysdeps/nacl/access.c (__ACCESS)[!__ACCESS]: Define as
__access.
(DO_NACL_CALL): New macro.
(__access): Rename to __ACCESS. Use DO_NACL_CALL instead of
NACL_CALL.
[!NOERRNO]: Set weak alias to access.
* sysdeps/nacl/nacl-interfaces.h (NACL_CALL_NOERRNO): New
macro.
* sysdeps/unix/access_noerrno.c: New file.
* sysdeps/unix/sysv/linux/generic/access.c: Include sysdep.h.
(__ACCESS)[!__ACCESS]: Define as __access.
(__access): Rename to __ACCESS.
[NOERRNO]: Call faccessat syscall without setting errno.
---
include/unistd.h | 6 +++++
io/Makefile | 1 +
io/access.c | 10 ++++++++-
io/access_noerrno.c | 21 ++++++++++++++++++
sysdeps/mach/hurd/access.c | 20 +++++++++++++----
sysdeps/nacl/access.c | 16 ++++++++++++--
sysdeps/nacl/nacl-interfaces.h | 4 ++++
sysdeps/unix/access_noerrno.c | 38 ++++++++++++++++++++++++++++++++
sysdeps/unix/sysv/linux/generic/access.c | 19 +++++++++++++++-
9 files changed, 127 insertions(+), 8 deletions(-)
create mode 100644 io/access_noerrno.c
create mode 100644 sysdeps/unix/access_noerrno.c
diff --git a/include/unistd.h b/include/unistd.h
index d2802b2..6144f41 100644
--- a/include/unistd.h
+++ b/include/unistd.h
@@ -181,6 +181,12 @@ extern int __getlogin_r_loginuid (char *name, size_t namesize)
# include <dl-unistd.h>
# endif
+# if IS_IN (rtld) || !defined SHARED
+/* __access variant that does not set errno. Used in very early initialization
+ code in libc.a and ld.so. */
+extern __typeof (__access) __access_noerrno attribute_hidden;
+# endif
+
__END_DECLS
# endif
diff --git a/io/Makefile b/io/Makefile
index e5493b3..1ebb0d0 100644
--- a/io/Makefile
+++ b/io/Makefile
@@ -40,6 +40,7 @@ routines := \
mkdir mkdirat \
open open_2 open64 open64_2 openat openat_2 openat64 openat64_2 \
read write lseek lseek64 access euidaccess faccessat \
+ access_noerrno \
fcntl flock lockf lockf64 \
close dup dup2 dup3 pipe pipe2 \
creat creat64 \
diff --git a/io/access.c b/io/access.c
index 4534704..80cfa98 100644
--- a/io/access.c
+++ b/io/access.c
@@ -19,10 +19,15 @@
#include <stddef.h>
#include <unistd.h>
+#ifndef __ACCESS
+# define __ACCESS __access
+#endif
+
/* Test for access to FILE. */
int
-__access (const char *file, int type)
+__ACCESS (const char *file, int type)
{
+#ifndef NOERRNO
if (file == NULL || (type & ~(R_OK|W_OK|X_OK|F_OK)) != 0)
{
__set_errno (EINVAL);
@@ -30,8 +35,11 @@ __access (const char *file, int type)
}
__set_errno (ENOSYS);
+#endif
return -1;
}
+#ifndef NOERRNO
stub_warning (access)
weak_alias (__access, access)
+#endif
diff --git a/io/access_noerrno.c b/io/access_noerrno.c
new file mode 100644
index 0000000..4bd531f
--- /dev/null
+++ b/io/access_noerrno.c
@@ -0,0 +1,21 @@
+/* Test for access to a file but do not set errno on error.
+ Copyright (C) 2016 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library; if not, see
+ <http://www.gnu.org/licenses/>. */
+
+#define NOERRNO 1
+#define __ACCESS __access_noerrno
+#include <access.c>
diff --git a/sysdeps/mach/hurd/access.c b/sysdeps/mach/hurd/access.c
index c308340..189fefe 100644
--- a/sysdeps/mach/hurd/access.c
+++ b/sysdeps/mach/hurd/access.c
@@ -22,9 +22,19 @@
#include <hurd/lookup.h>
#include <fcntl.h>
+#ifndef __ACCESS
+# define __ACCESS __access
+#endif
+
+#ifndef NOERRNO
+# define __HURD_FAIL(e) __hurd_fail (e)
+#else
+# define __HURD_FAIL(e) (e)
+#endif
+
/* Test for access to FILE by our real user and group IDs. */
int
-__access (const char *file, int type)
+__ACCESS (const char *file, int type)
{
error_t err;
file_t rcrdir, rcwdir, io;
@@ -120,13 +130,13 @@ __access (const char *file, int type)
if (rcwdir != MACH_PORT_NULL)
__mach_port_deallocate (__mach_task_self (), rcwdir);
if (err)
- return __hurd_fail (err);
+ return __HURD_FAIL (err);
/* Find out what types of access we are allowed to this file. */
err = __file_check_access (io, &allowed);
__mach_port_deallocate (__mach_task_self (), io);
if (err)
- return __hurd_fail (err);
+ return __HURD_FAIL (err);
flags = 0;
if (type & R_OK)
@@ -138,9 +148,11 @@ __access (const char *file, int type)
if (flags & ~allowed)
/* We are not allowed all the requested types of access. */
- return __hurd_fail (EACCES);
+ return __HURD_FAIL (EACCES);
return 0;
}
+#ifndef NOERRNO
weak_alias (__access, access)
+#endif
diff --git a/sysdeps/nacl/access.c b/sysdeps/nacl/access.c
index 95a0fb7..b7339e7 100644
--- a/sysdeps/nacl/access.c
+++ b/sysdeps/nacl/access.c
@@ -19,10 +19,22 @@
#include <unistd.h>
#include <nacl-interfaces.h>
+#ifndef __ACCESS
+# define __ACCESS __access
+#endif
+
+#ifndef NOERRNO
+# define DO_NACL_CALL NACL_CALL
+#else
+# define DO_NACL_CALL NACL_CALL_NOERRNO
+#endif
+
/* Test for access to FILE. */
int
-__access (const char *file, int type)
+__ACCESS (const char *file, int type)
{
- return NACL_CALL (__nacl_irt_dev_filename.access (file, type), 0);
+ return DO_NACL_CALL (__nacl_irt_dev_filename.access (file, type), 0);
}
+#ifndef NOERRNO
weak_alias (__access, access)
+#endif
diff --git a/sysdeps/nacl/nacl-interfaces.h b/sysdeps/nacl/nacl-interfaces.h
index b7b45bb..fd8d580 100644
--- a/sysdeps/nacl/nacl-interfaces.h
+++ b/sysdeps/nacl/nacl-interfaces.h
@@ -113,4 +113,8 @@ __nacl_fail (int err)
#define NACL_CALL(err, val) \
({ int _err = (err); _err ? __nacl_fail (_err) : (val); })
+/* Don't set errno. */
+#define NACL_CALL_NOERRNO(err, val) \
+ ({ int _err = (err); _err ? _err : (val); })
+
#endif /* nacl-interfaces.h */
diff --git a/sysdeps/unix/access_noerrno.c b/sysdeps/unix/access_noerrno.c
new file mode 100644
index 0000000..1ff90a2
--- /dev/null
+++ b/sysdeps/unix/access_noerrno.c
@@ -0,0 +1,38 @@
+/* Test for access to a file but do not set errno on error.
+ Copyright (C) 2016 Free Software Foundation, Inc.
+ This file is part of the GNU C Library.
+ Contributed by Chris Metcalf <cmetcalf@tilera.com>, 2011.
+
+ The GNU C Library is free software; you can redistribute it and/or
+ modify it under the terms of the GNU Lesser General Public
+ License as published by the Free Software Foundation; either
+ version 2.1 of the License, or (at your option) any later version.
+
+ The GNU C Library is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with the GNU C Library. If not, see
+ <http://www.gnu.org/licenses/>. */
+
+#include <errno.h>
+#include <stddef.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sysdep-cancel.h>
+#include <sysdep.h>
+
+/* Test for access to FILE. */
+int
+__access_noerrno (const char *file, int type)
+{
+ INTERNAL_SYSCALL_DECL (err);
+ int res;
+ res = INTERNAL_SYSCALL (access, err, 2, file, type);
+ if (INTERNAL_SYSCALL_ERROR_P (res, err))
+ return INTERNAL_SYSCALL_ERRNO (res, err);
+ else
+ return 0;
+}
diff --git a/sysdeps/unix/sysv/linux/generic/access.c b/sysdeps/unix/sysv/linux/generic/access.c
index 586aa93..5bafc06 100644
--- a/sysdeps/unix/sysv/linux/generic/access.c
+++ b/sysdeps/unix/sysv/linux/generic/access.c
@@ -21,11 +21,28 @@
#include <unistd.h>
#include <fcntl.h>
#include <sysdep-cancel.h>
+#include <sysdep.h>
+
+#ifndef __ACCESS
+# define __ACCESS __access
+#endif
/* Test for access to FILE. */
int
-__access (const char *file, int type)
+__ACCESS (const char *file, int type)
{
+#ifndef NOERRNO
return INLINE_SYSCALL (faccessat, 3, AT_FDCWD, file, type);
+#else
+ INTERNAL_SYSCALL_DECL (err);
+ int res;
+ res = INTERNAL_SYSCALL (faccessat, err, 3, AT_FDCWD, file, type);
+ if (INTERNAL_SYSCALL_ERROR_P (res, err))
+ return INTERNAL_SYSCALL_ERRNO (res, err);
+ else
+ return 0;
+#endif
}
+#ifndef NOERRNO
weak_alias (__access, access)
+#endif
--
2.7.4