insane.bbclass: add host-user-contaminated test

- Add a test which checks for any paths outside of /home which are owned by
  the user running bitbake.
- Add the test to WARN_QA by default.

This test has been in meta-mentor for some time, and in our ERROR_QA for our
builds, and has caught a number of issues for us.

(From OE-Core rev: 1854dc60a4c7e97f0d6d26208fd42bf0dc1bfa7f)

Signed-off-by: Christopher Larson <chris_larson@mentor.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/classes/insane.bbclass

@@ -32,14 +32,14 @@ WARN_QA ?= "ldflags useless-rpaths rpaths staticdev libdir xorg-driver-abi \
             installed-vs-shipped compile-host-path install-host-path \
             pn-overrides infodir build-deps file-rdeps \
             unknown-configure-option symlink-to-sysroot multilib \
-            invalid-pkgconfig \
+            invalid-pkgconfig host-user-contaminated \
             "
 ERROR_QA ?= "dev-so debug-deps dev-deps debug-files arch pkgconfig la \
             perms dep-cmp pkgvarcheck perm-config perm-line perm-link \
             split-strip packages-list pkgv-undefined var-undefined \
             version-going-backwards expanded-d invalid-chars \
             "
-FAKEROOT_QA = ""
+FAKEROOT_QA = "host-user-contaminated"
 FAKEROOT_QA[doc] = "QA tests which need to run under fakeroot. If any \
 enabled tests are listed here, the do_package_qa task will run under fakeroot."
 
@@ -969,6 +969,39 @@ def package_qa_check_encoding(keys, encode, d):
         if not sane:
             break
 
+HOST_USER_UID := "${@os.getuid()}"
+HOST_USER_GID := "${@os.getgid()}"
+
+QAPATHTEST[host-user-contaminated] = "package_qa_check_host_user"
+def package_qa_check_host_user(path, name, d, elf, messages):
+    """Check for paths outside of /home which are owned by the user running bitbake."""
+
+    if not os.path.lexists(path):
+        return
+
+    dest = d.getVar('PKGDEST', True)
+    home = os.path.join(dest, 'home')
+    if path == home or path.startswith(home + os.sep):
+        return
+
+    try:
+        stat = os.lstat(path)
+    except OSError as exc:
+        import errno
+        if exc.errno != errno.ENOENT:
+            raise
+    else:
+        check_uid = int(d.getVar('HOST_USER_UID', True))
+        if stat.st_uid == check_uid:
+            messages["host-user-contaminated"] = "%s is owned by uid %d, which is the same as the user running bitbake. This may be due to host contamination" % (path, check_uid)
+            return False
+
+        check_gid = int(d.getVar('HOST_USER_GID', True))
+        if stat.st_gid == check_gid:
+            messages["host-user-contaminated"] = "%s is owned by gid %d, which is the same as the user running bitbake. This may be due to host contamination" % (path, check_gid)
+            return False
+    return True
+
 # The PACKAGE FUNC to scan each package
 python do_package_qa () {
     import subprocess