[PATCH 3c/6] Installed-header hygiene (BZ#20366): struct osockaddr.

[Zack Weinberg <zackw at panix dot com>]

sys/socket.h defines struct osockaddr only under __USE_MISC, whereas
protocols/talkd.h requires it unconditionally.  Rather than complicate
sys/socket.h with a __need macro or duplicate the definition, I am
introducing a new concept: tiny headers named bits/types/TYPE.h that
define TYPE and nothing else.  This can, I hope, ultimately replace
*all* the __need macros.  The guard macro for such headers will be
__TYPE_defined, just in case application or third-party library
code is looking at them.

	* socket/bits/types/struct_osockaddr.h: New header.
	* include/bits/types/struct_osockaddr.h: New wrapper.
	* socket/Makefile: Install the new header.
	* socket/sys/socket.h
	* inet/protocols/talkd.h: Refer to bits/types/struct_osockaddr.h
	for the definition of struct osockaddr.
---
 include/bits/types/struct_osockaddr.h |  1 +
 inet/protocols/talkd.h                |  1 +
 socket/Makefile                       |  3 ++-
 socket/bits/types/struct_osockaddr.h  | 12 ++++++++++++
 socket/sys/socket.h                   |  8 +-------
 5 files changed, 17 insertions(+), 8 deletions(-)
 create mode 100644 include/bits/types/struct_osockaddr.h
 create mode 100644 socket/bits/types/struct_osockaddr.h

diff --git a/include/bits/types/struct_osockaddr.h b/include/bits/types/struct_osockaddr.h
new file mode 100644
index 0000000..78f3188
--- /dev/null
+++ b/include/bits/types/struct_osockaddr.h
@@ -0,0 +1 @@
+#include "../../socket/bits/types/struct_osockaddr.h"
diff --git a/inet/protocols/talkd.h b/inet/protocols/talkd.h
index 34e2654..09bd8a9 100644
--- a/inet/protocols/talkd.h
+++ b/inet/protocols/talkd.h
@@ -53,6 +53,7 @@
 #include <sys/types.h>
 #include <sys/socket.h>
 #include <stdint.h>
+#include <bits/types/struct_osockaddr.h>
 
 /*
  * Client->server request message format.
diff --git a/socket/Makefile b/socket/Makefile
index 92450e8..6be5ec7 100644
--- a/socket/Makefile
+++ b/socket/Makefile
@@ -23,7 +23,8 @@ subdir	:= socket
 include ../Makeconfig
 
 headers	:= sys/socket.h sys/un.h bits/sockaddr.h bits/socket.h \
-	   bits/socket2.h sys/socketvar.h net/if.h
+	   bits/socket2.h bits/types/struct_osockaddr.h \
+	   sys/socketvar.h net/if.h
 
 routines := accept bind connect getpeername getsockname getsockopt	\
 	    listen recv recvfrom recvmsg send sendmsg sendto		\
diff --git a/socket/bits/types/struct_osockaddr.h b/socket/bits/types/struct_osockaddr.h
new file mode 100644
index 0000000..e0bf59d
--- /dev/null
+++ b/socket/bits/types/struct_osockaddr.h
@@ -0,0 +1,12 @@
+#ifndef __osockaddr_defined
+#define __osockaddr_defined 1
+
+/* This is the 4.3 BSD `struct sockaddr' format, which is used as wire
+   format in the grotty old 4.3 `talk' protocol.  */
+struct osockaddr
+{
+  unsigned short int sa_family;
+  unsigned char sa_data[14];
+};
+
+#endif
diff --git a/socket/sys/socket.h b/socket/sys/socket.h
index c9f0f50..5be1b91 100644
--- a/socket/sys/socket.h
+++ b/socket/sys/socket.h
@@ -38,13 +38,7 @@ __BEGIN_DECLS
 #include <bits/socket.h>
 
 #ifdef __USE_MISC
-/* This is the 4.3 BSD `struct sockaddr' format, which is used as wire
-   format in the grotty old 4.3 `talk' protocol.  */
-struct osockaddr
-  {
-    unsigned short int sa_family;
-    unsigned char sa_data[14];
-  };
+# include <bits/types/struct_osockaddr.h>
 #endif
 
 /* The following constants should be used for the second parameter of
-- 
2.9.3