Fix CMSG and ALIGN macro usage.

Previously we had to include <machine/param.h> or <sys/param.h> bogusly
due to the fact that <sys/socket.h> CMSG macros needed the ALIGN macro,
which was defined in param.h.  However, including param.h was a disaster
for namespace pollution.
This solution, as contributed by shin a while ago, fixes it elegantly
by wrapping the definitions around some namespace pollution preventer
definitions.
This patch was long overdue.
This should allow any network programmer to use <sys/socket.h> as
before.

PR:		19971, 20530
Submitted by:	Martin Kaeske <MartinKaeske@lausitz.net>
		Mark Andrews <Mark.Andrews@nominum.com>
Patch submitted by:	shin
Reviewed by:	bde

3 files changed, 76 insertions, 36 deletions

diff --git a/sys/alpha/include/param.h b/sys/alpha/include/param.h
index ae641f6..7c0f1af 100644
--- a/sys/alpha/include/param.h
+++ b/sys/alpha/include/param.h
@@ -46,15 +46,43 @@
 /*
  * Machine dependent constants for the Alpha.
  */
+
+/*
+ * Round p (pointer or byte index) up to a correctly-aligned value for all
+ * data types (int, long, ...).   The result is u_long and must be cast to
+ * any desired pointer type.
+ *
+ * ALIGNED_POINTER is a boolean macro that checks whether an address
+ * is valid to fetch data elements of type t from on this architecture.
+ * This does not reflect the optimal alignment, just the possibility
+ * (within reasonable limits). 
+ *
+ */
+#ifndef _ALIGNBYTES
+#define	_ALIGNBYTES		7
+#endif
+#ifndef _ALIGN
+#define	_ALIGN(p)		(((u_long)(p) + _ALIGNBYTES) &~ _ALIGNBYTES)
+#endif
+#ifndef _ALIGNED_POINTER
+#define _ALIGNED_POINTER(p,t)	((((u_long)(p)) & (sizeof(t)-1)) == 0)
+#endif
+
 #ifndef _MACHINE
 #define	_MACHINE	alpha
 #endif
-#ifndef MACHINE
-#define	MACHINE		"alpha"
-#endif
 #ifndef _MACHINE_ARCH
 #define	_MACHINE_ARCH	alpha
 #endif
+
+#ifndef _NO_NAMESPACE_POLLUTION
+
+#ifndef _MACHINE_PARAM_H_
+#define _MACHINE_PARAM_H_
+
+#ifndef MACHINE
+#define	MACHINE		"alpha"
+#endif
 #ifndef MACHINE_ARCH
 #define	MACHINE_ARCH	"alpha"
 #endif
@@ -76,20 +104,9 @@
 #define MAXCPU		1
 #endif
 
-/*
- * Round p (pointer or byte index) up to a correctly-aligned value for all
- * data types (int, long, ...).   The result is u_long and must be cast to
- * any desired pointer type.
- *
- * ALIGNED_POINTER is a boolean macro that checks whether an address
- * is valid to fetch data elements of type t from on this architecture.
- * This does not reflect the optimal alignment, just the possibility
- * (within reasonable limits). 
- *
- */
-#define	ALIGNBYTES		7
-#define	ALIGN(p)		(((u_long)(p) + ALIGNBYTES) &~ ALIGNBYTES)
-#define ALIGNED_POINTER(p,t)	((((u_long)(p)) & (sizeof(t)-1)) == 0)
+#define	ALIGNBYTES		_ALIGNBYTES
+#define	ALIGN(p)		_ALIGN(p)
+#define ALIGNED_POINTER(p,t)	_ALIGNED_POINTER(p,t)
 
 #define	PAGE_SIZE	(1 << ALPHA_PGSHIFT)		/* bytes/page */
 #define PAGE_SHIFT	ALPHA_PGSHIFT
@@ -157,3 +174,6 @@
 #define	alpha_ptob(x)		((unsigned long)(x) << PAGE_SHIFT)
 
 #define pgtok(x)                ((x) * (PAGE_SIZE / 1024)) 
+
+#endif /* !_MACHINE_PARAM_H_ */
+#endif /* !_NO_NAMESPACE_POLLUTION */
diff --git a/sys/i386/include/param.h b/sys/i386/include/param.h
index 0d17297..dffc648 100644
--- a/sys/i386/include/param.h
+++ b/sys/i386/include/param.h
@@ -37,21 +37,37 @@
  * $FreeBSD$
  */
 
-#ifndef _MACHINE_PARAM_H_
-#define	_MACHINE_PARAM_H_
-
 /*
  * Machine dependent constants for Intel 386.
  */
+
+/*
+ * Round p (pointer or byte index) up to a correctly-aligned value
+ * for all data types (int, long, ...).   The result is unsigned int
+ * and must be cast to any desired pointer type.
+ */
+#ifndef _ALIGNBYTES
+#define _ALIGNBYTES	(sizeof(int) - 1)
+#endif
+#ifndef _ALIGN
+#define _ALIGN(p)	(((unsigned)(p) + _ALIGNBYTES) & ~_ALIGNBYTES)
+#endif
+
 #ifndef _MACHINE
 #define	_MACHINE	i386
 #endif
-#ifndef MACHINE
-#define MACHINE		"i386"
-#endif
 #ifndef _MACHINE_ARCH
 #define	_MACHINE_ARCH	i386
 #endif
+
+#ifndef _NO_NAMESPACE_POLLUTION
+
+#ifndef _MACHINE_PARAM_H_
+#define	_MACHINE_PARAM_H_
+
+#ifndef MACHINE
+#define MACHINE		"i386"
+#endif
 #ifndef MACHINE_ARCH
 #define	MACHINE_ARCH	"i386"
 #endif
@@ -70,13 +86,8 @@
 #define MAXCPU		1
 #endif /* SMP */
 
-/*
- * Round p (pointer or byte index) up to a correctly-aligned value
- * for all data types (int, long, ...).   The result is unsigned int
- * and must be cast to any desired pointer type.
- */
-#define ALIGNBYTES	(sizeof(int) - 1)
-#define ALIGN(p)	(((unsigned)(p) + ALIGNBYTES) & ~ALIGNBYTES)
+#define ALIGNBYTES	_ALIGNBYTES
+#define ALIGN(p)	_ALIGN(p)
 
 #define PAGE_SHIFT	12		/* LOG2(PAGE_SIZE) */
 #define PAGE_SIZE	(1<<PAGE_SHIFT)	/* bytes/page */
@@ -155,3 +166,4 @@
 #define	pgtok(x)		((x) * (PAGE_SIZE / 1024))
 
 #endif /* !_MACHINE_PARAM_H_ */
+#endif /* !_NO_NAMESPACE_POLLUTION */
diff --git a/sys/sys/socket.h b/sys/sys/socket.h
index 548f4f0..2d76eeb 100644
--- a/sys/sys/socket.h
+++ b/sys/sys/socket.h
@@ -37,6 +37,14 @@
 #ifndef _SYS_SOCKET_H_
 #define	_SYS_SOCKET_H_
 
+#ifdef _NO_NAMESPACE_POLLUTION
+#include <machine/param.h>
+#else
+#define _NO_NAMESPACE_POLLUTION
+#include <machine/param.h>
+#undef _NO_NAMESPACE_POLLUTION
+#endif
+
 /*
  * Definitions related to sockets: types, address families, options.
  */
@@ -358,22 +366,22 @@ struct cmsgcred {
 
 /* given pointer to struct cmsghdr, return pointer to data */
 #define	CMSG_DATA(cmsg)		((u_char *)(cmsg) + \
-				 ALIGN(sizeof(struct cmsghdr)))
+				 _ALIGN(sizeof(struct cmsghdr)))
 
 /* given pointer to struct cmsghdr, return pointer to next cmsghdr */
 #define	CMSG_NXTHDR(mhdr, cmsg)	\
-	(((caddr_t)(cmsg) + ALIGN((cmsg)->cmsg_len) + \
-	  ALIGN(sizeof(struct cmsghdr)) > \
+	(((caddr_t)(cmsg) + _ALIGN((cmsg)->cmsg_len) + \
+	  _ALIGN(sizeof(struct cmsghdr)) > \
 	    (caddr_t)(mhdr)->msg_control + (mhdr)->msg_controllen) ? \
 	    (struct cmsghdr *)NULL : \
-	    (struct cmsghdr *)((caddr_t)(cmsg) + ALIGN((cmsg)->cmsg_len)))
+	    (struct cmsghdr *)((caddr_t)(cmsg) + _ALIGN((cmsg)->cmsg_len)))
 
 #define	CMSG_FIRSTHDR(mhdr)	((struct cmsghdr *)(mhdr)->msg_control)
 
 /* RFC 2292 additions */
 	
-#define	CMSG_SPACE(l)		(ALIGN(sizeof(struct cmsghdr)) + ALIGN(l))
-#define	CMSG_LEN(l)		(ALIGN(sizeof(struct cmsghdr)) + (l))
+#define	CMSG_SPACE(l)		(_ALIGN(sizeof(struct cmsghdr)) + _ALIGN(l))
+#define	CMSG_LEN(l)		(_ALIGN(sizeof(struct cmsghdr)) + (l))
 
 /* "Socket"-level control message types: */
 #define	SCM_RIGHTS	0x01		/* access rights (array of int) */