From d630a05f40fa67600be81eb1dab77bef8903c03d Mon Sep 17 00:00:00 2001
From: Doug Ambrisko <ambrisko@FreeBSD.org>
Date: Fri, 2 Dec 2005 00:50:30 +0000
Subject: [PATCH] Add support to easily build FreeBSD unpacked in a chroot of
 another FreeBSD machine.  To do this add the man 1 uname changes to
 __xuname.c so we can override the settings it reports.  Add OSVERSION
 override to getosreldate.  Finally which Makefile.inc1 to use uname -m
 instead of  sysctl -n hw.machine_arch to get the arch. type.

With these change you can put a complete FreeBSD OS image into a
chroot set:
	UNAME_s=FreeBSD
	UNAME_r=4.7-RELEASE
	UNAME_v="FreeBSD $UNAME_r #1: Fri Jul 22 20:32:52 PDT 2005 fake@fake:/usr/obj/usr/src/sys/FAKE"
	UNAME_m=i386
	UNAME_p=i386
	OSVERSION=470000
on an amd64 or i386 and it just work including building ports and using
pkg_add -r etc.  The caveat for this example is that these patches
have to be applied to FreeBSD 4.7 and the uname(1) changes need to
be merged.  This also addresses issue with libtool.

This is usefull for when a build machine has been trashed for an
old release and we want to do a build on a new machine that FreeBSD
4.7 won't run on ...
---
 Makefile.inc1               | 2 +-
 lib/libc/gen/__xuname.c     | 8 ++++++++
 lib/libc/gen/getosreldate.c | 5 +++++
 3 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/Makefile.inc1 b/Makefile.inc1
index 8f140a6ff6d..6a93be9aa8f 100644
--- a/Makefile.inc1
+++ b/Makefile.inc1
@@ -122,7 +122,7 @@ _CPUTYPE!=	MAKEFLAGS= CPUTYPE=${_TARGET_CPUTYPE} ${MAKE} \
 .error CPUTYPE global should be set with ?=.
 .endif
 .if make(buildworld)
-BUILD_ARCH!=	sysctl -n hw.machine_arch
+BUILD_ARCH!=	uname -m
 .if ${MACHINE_ARCH} != ${BUILD_ARCH}
 .error To cross-build, set TARGET_ARCH.
 .endif
diff --git a/lib/libc/gen/__xuname.c b/lib/libc/gen/__xuname.c
index 4d1be8c04f1..c7965743675 100644
--- a/lib/libc/gen/__xuname.c
+++ b/lib/libc/gen/__xuname.c
@@ -71,6 +71,8 @@ __xuname(int namesize, void *namebuf)
 			rval = -1;
 	}
 	name->sysname[sizeof(name->sysname) - 1] = '\0';
+	if ((p = getenv("UNAME_s")))
+		strncpy(name->sysname, p, sizeof(name->sysname));
 
 	mib[0] = CTL_KERN;
 	mib[1] = KERN_HOSTNAME;
@@ -95,6 +97,8 @@ __xuname(int namesize, void *namebuf)
 			rval = -1;
 	}
 	name->release[sizeof(name->release) - 1] = '\0';
+	if ((p = getenv("UNAME_r")))
+		strncpy(name->release, p, sizeof(name->release));
 
 	/* The version may have newlines in it, turn them into spaces. */
 	mib[0] = CTL_KERN;
@@ -116,6 +120,8 @@ __xuname(int namesize, void *namebuf)
 				*p = '\0';
 		}
 	}
+	if ((p = getenv("UNAME_v")))
+		strncpy(name->version, p, sizeof(name->version));
 
 	mib[0] = CTL_HW;
 	mib[1] = HW_MACHINE;
@@ -128,5 +134,7 @@ __xuname(int namesize, void *namebuf)
 			rval = -1;
 	}
 	name->machine[sizeof(name->machine) - 1] = '\0';
+	if ((p = getenv("UNAME_m")))
+		strncpy(name->machine, p, sizeof(name->machine));
 	return (rval);
 }
diff --git a/lib/libc/gen/getosreldate.c b/lib/libc/gen/getosreldate.c
index 22c400d1c73..03a00c1b6a8 100644
--- a/lib/libc/gen/getosreldate.c
+++ b/lib/libc/gen/getosreldate.c
@@ -39,6 +39,7 @@ __FBSDID("$FreeBSD$");
 
 #include <sys/param.h>
 #include <sys/sysctl.h>
+#include <stdlib.h>
 
 #include <osreldate.h>
 
@@ -49,10 +50,14 @@ getosreldate(void)
 	size_t size;
 	int value;
 
+	char *temp;
+
 	mib[0] = CTL_KERN;
 	mib[1] = KERN_OSRELDATE;
 	size = sizeof value;
 	if (sysctl(mib, 2, &value, &size, NULL, 0) == -1)
 		return (-1);
+	if ((temp = getenv("OSVERSION")))
+		value = atoi(temp);
 	return (value);
 }