[glibc/zack/no-nested-includes] Don’t include string.h from sys/un.h.

[Zack Weinberg <zack@sourceware.org>]

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https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=fd0a2720650fa560321a7277500b316aec2df503

commit fd0a2720650fa560321a7277500b316aec2df503
Author: Zack Weinberg <zackw@panix.com>
Date:   Wed May 22 12:03:57 2019 -0400

    Don’t include string.h from sys/un.h.
    
    sys/un.h needs strlen in order to define SUN_LEN, but does not need
    any of the other things declared by string.h; the path of least
    resistance is to prototype strlen locally.
    
    Also, the construct being used to get the size of everything up to the
    sun_path member contains a formal dereference of a null pointer and
    therefore has undefined behavior.  Replace with __SOCKADDR_COMMON_SIZE.
    
    Some old RPC code was relying on sys/un.h to provide all of string.h.
    
    	* sys/un.h [__USE_MISC]: Don’t include string.h.
    	Include bits/types/size_t.h.  Prototype strlen locally.
    	Use __SOCKADDR_COMMON_SIZE for size of leading members of
    	struct sockaddr_un.
    
    	* nis/nis_domain_of.c, nis/yp_xdr.c, sunrpc/svc.c:
    	Include string.h.
    
    	* scripts/check-obsolete-constructs.py (HEADER_ALLOWED_INCLUDES):
    	Update.

Diff:
---
 nis/nis_domain_of.c                  | 1 +
 nis/yp_xdr.c                         | 1 +
 scripts/check-obsolete-constructs.py | 1 -
 socket/sys/un.h                      | 8 +++++---
 sunrpc/svc.c                         | 1 +
 5 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/nis/nis_domain_of.c b/nis/nis_domain_of.c
index 44c5b04..da26df3 100644
--- a/nis/nis_domain_of.c
+++ b/nis/nis_domain_of.c
@@ -17,6 +17,7 @@
    <http://www.gnu.org/licenses/>.  */
 
 #include <rpcsvc/nis.h>
+#include <string.h>
 #include <shlib-compat.h>
 
 nis_name
diff --git a/nis/yp_xdr.c b/nis/yp_xdr.c
index 3b57673..4c9f1d2 100644
--- a/nis/yp_xdr.c
+++ b/nis/yp_xdr.c
@@ -31,6 +31,7 @@
 
 #include <rpcsvc/yp.h>
 #include <rpcsvc/ypclnt.h>
+#include <string.h>
 #include <shlib-compat.h>
 
 /* The NIS v2 protocol suggests 1024 bytes as a maximum length of all fields.
diff --git a/scripts/check-obsolete-constructs.py b/scripts/check-obsolete-constructs.py
index bca0f12..d230fcf 100755
--- a/scripts/check-obsolete-constructs.py
+++ b/scripts/check-obsolete-constructs.py
@@ -539,7 +539,6 @@ HEADER_ALLOWED_INCLUDES = {
     "sys/types.h":                 [ "endian.h" ],
 
     "sys/uio.h":                   [ "sys/types.h" ],
-    "sys/un.h":                    [ "string.h" ],
 
     # POSIX networking headers
     # allowed: netdb.h -> netinet/in.h
diff --git a/socket/sys/un.h b/socket/sys/un.h
index 8c7433a..540560e 100644
--- a/socket/sys/un.h
+++ b/socket/sys/un.h
@@ -34,11 +34,13 @@ struct sockaddr_un
 
 
 #ifdef __USE_MISC
-# include <string.h>		/* For prototype of `strlen'.  */
+#include <bits/types/size_t.h>
+
+extern size_t strlen (const char *__s)
+     __THROW __attribute_pure__ __nonnull ((1));
 
 /* Evaluate to actual length of the `sockaddr_un' structure.  */
-# define SUN_LEN(ptr) ((size_t) (((struct sockaddr_un *) 0)->sun_path)	      \
-		      + strlen ((ptr)->sun_path))
+# define SUN_LEN(ptr) (__SOCKADDR_COMMON_SIZE + strlen ((ptr)->sun_path))
 #endif
 
 __END_DECLS
diff --git a/sunrpc/svc.c b/sunrpc/svc.c
index 95ecfbb..8042019 100644
--- a/sunrpc/svc.c
+++ b/sunrpc/svc.c
@@ -53,6 +53,7 @@
  */
 
 #include <errno.h>
+#include <string.h>
 #include <unistd.h>
 #include <rpc/rpc.h>
 #include <rpc/svc.h>