Bug#276138: sys/un.h: SUN_LEN cannot be used in abstract namespace

[Christian Häggström <chm@c00.info>]

Package: libc6-dev
Version: 2.3.2.ds1-17
Severity: minor
File: /usr/include/sys/un.h

The man-page unix(7) describes abstract namespace as follows.

   sun_family  always contains AF_UNIX.  sun_path contains the zero-termi-
   nated pathname of the socket in the file system.   If  sun_path  starts
   with  a zero byte it refers to the abstract namespace maintained by the
   Unix protocol module.  The socket's address in this namespace is  given
   by  the rest of the bytes in sun_path.  Note that names in the abstract
   namespace are not zero-terminated.

The macro SUN_LEN currently is defined as

#define SUN_LEN(ptr) ((size_t) (((struct sockaddr_un *) 0)->sun_path) + strlen ((ptr)->sun_path))

I suggest that a check should be made for a zero first byte, and in that
case return sizeof(struct sockaddr_un), as the manpage says.

If it is the programmers responsibility to check for abstract
namespace, I suggest adding a comment about that close to the
definition of SUN_LEN.

Thanks!

Debian Release: 3.1
  APT prefers unstable
  APT policy: (500, 'unstable'), (1, 'experimental')
Architecture: i386 (i686)
Kernel: Linux 2.6.8.1
Locale: LANG=sv_SE, LC_CTYPE=sv_SE

Versions of packages libc6-dev depends on:
ii  libc6                2.3.2.ds1-17        GNU C Library: Shared libraries an
ii  linux-kernel-headers 2.5.999-test7-bk-17 Linux Kernel Headers for developme

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