Re: [PATCH] y2038: fix socket.h header inclusion

* Arnd Bergmann:

On Thu, Mar 14, 2019 at 7:41 PM Florian Weimer [off-list ref] wrote:

quoted

* Arnd Bergmann:

quoted

diff --git a/arch/alpha/include/uapi/asm/socket.h

b/arch/alpha/include/uapi/asm/socket.h
index 0d0fddb7e738..976e89b116e5 100644

--- a/arch/alpha/include/uapi/asm/socket.h
+++ b/arch/alpha/include/uapi/asm/socket.h

@@ -2,8 +2,8 @@
 #ifndef _UAPI_ASM_SOCKET_H
 #define _UAPI_ASM_SOCKET_H

+#include <linux/posix_types.h>
 #include <asm/sockios.h>
-#include <asm/bitsperlong.h>

This breaks POSIX conformance in glibc because the
<linux/posix_types.h> header is not namespace clean.  It contains the
identifiers fds_bits and val:

        unsigned long fds_bits[__FD_SETSIZE / (8 * sizeof(long))];

        int     val[2];

What is problematic about the struct members here? I had thought that
only the struct names have to be in a namespace to be usable here,
but not the members.

According POSIX, a user can do this:

#define fds_bits 1024

before including the <sys/socket.h> header file.  Similarly for val.

Since glibc pulls in <asm/socket.h> indirectly, the result is a parse
error, even though the programmer did nothing wrong (fds_bits is not
an identifier used by POSIX, nor is it in the implementation
namespace, ans <sys/socket.h> is a POSIX header).

We could use asm/posix_types.h instead of linux/posix_types.h,
would that address your concern?

It should fix the fds_bits case, I think.  But
<asm-generic/posix_types.h> still uses val, so that part of the issue
remains.