New internal function __access_noerrno

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.

Checked on x86_64.

	* hurd/hurd.h (__hurd_fail_noerrno): New function.
	* include/unistd.h [IS_IN (rtld) || !defined SHARED]: Declare
	__access_noerrno.
	* io/access.c (__access_noerrno): New function.
	* sysdeps/mach/hurd/access.c (hurd_fail_seterrno): New function.
	(hurd_fail_seterrno): Likewise.
	(access_common): Likewise.
	(__access_noerrno): Likewise.
	* sysdeps/nacl/access.c (__access_noerrno): Likewise.
	* sysdeps/unix/sysv/linux/access.c (__access_noerrno): Likewise.
	* sysdeps/nacl/nacl-interfaces.h (NACL_CALL_NOERRNO): New
	macro.

1 files changed, 15 insertions, 0 deletions

diff --git a/sysdeps/unix/sysv/linux/access.c b/sysdeps/unix/sysv/linux/access.c
index 8f003df27c..adefbcaac6 100644
--- a/sysdeps/unix/sysv/linux/access.c
+++ b/sysdeps/unix/sysv/linux/access.c
@@ -21,6 +21,21 @@
 #include <sysdep-cancel.h>
 
 int
+__access_noerrno (const char *file, int type)
+{
+  int res;
+  INTERNAL_SYSCALL_DECL (err);
+#ifdef __NR_access
+  res = INTERNAL_SYSCALL_CALL (access, err, file, type);
+#else
+  res = INTERNAL_SYSCALL_CALL (faccessat, err, AT_FDCWD, file, type);
+#endif
+  if (INTERNAL_SYSCALL_ERROR_P (res, err))
+    return INTERNAL_SYSCALL_ERRNO (res, err);
+  return 0;
+}
+
+int
 __access (const char *file, int type)
 {
 #ifdef __NR_access