[OE-core] [PATCH V2 3/3] populate_sdk_ext: consider custom configuration in local.conf

[Chen Qi]

Copy the contents of local.conf under TOPDIR into the final generated
local.conf. In this way, custom settings are also made into the final
local.conf like IMAGE_INSTALL, DISTRO_FEATURES, VIRTUAL-RUNTIME_xxx, etc.

Before this change, installing extensible SDK would usually report failure
when preparing the build system if the user has custom configuration for
DISTRO_FEATURES in local.conf. Also, items in IMAGE_INSTALL_append in local.conf
also don't get built correctly.

This patch solves the above problem by making use of the bb.utils.edit_metadata.

In addition, we check to avoid any setting that might lead to host path
bleeding into SDK's configuration. Basically, variables with values starting
with '/' are removed. A whitelist mechanism is introduced so that users could
specify variables that should not be ignored. The name of the whitelist is
SDK_LOCAL_CONF_WHITELIST.

[YOCTO #7616]

Signed-off-by: Chen Qi <Qi.Chen at windriver.com>
---
 meta/classes/populate_sdk_ext.bbclass | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/meta/classes/populate_sdk_ext.bbclass b/meta/classes/populate_sdk_ext.bbclass
index 2fc4c11..08130d4 100644
--- a/meta/classes/populate_sdk_ext.bbclass
+++ b/meta/classes/populate_sdk_ext.bbclass
@@ -16,6 +16,7 @@ SDK_RDEPENDS_append_task-populate-sdk-ext = " ${SDK_TARGETS}"
 SDK_RELOCATE_AFTER_INSTALL_task-populate-sdk-ext = "0"
 
 SDK_META_CONF_WHITELIST ?= "MACHINE DISTRO PACKAGE_CLASSES"
+SDK_LOCAL_CONF_WHITELIST ?= ""
 
 SDK_TARGETS ?= "${PN}"
 OE_INIT_ENV_SCRIPT ?= "oe-init-build-env"
@@ -108,12 +109,28 @@ python copy_buildsystem () {
         f.write('    "\n')
 
     # Create local.conf
+    local_conf_whitelist = d.getVar('SDK_LOCAL_CONF_WHITELIST', True).split()
+    def handle_var(varname, origvalue, op, newlines):
+        if origvalue.strip().startswith('/') and not varname in local_conf_whitelist:
+            newlines.append('# Removed original setting of %s\n' % varname)
+            return None, op, 0, True
+        else:
+            return origvalue, op, 0, True
+    varlist = ['[^#=+ ]*']
+    builddir = d.getVar('TOPDIR', True)
+    with open(builddir + '/conf/local.conf', 'r') as f:
+        oldlines = f.readlines()
+    (updated, newlines) = bb.utils.edit_metadata(oldlines, varlist, handle_var)
+
     with open(baseoutpath + '/conf/local.conf', 'w') as f:
         f.write('# WARNING: this configuration has been automatically generated and in\n')
         f.write('# most cases should not be edited. If you need more flexibility than\n')
         f.write('# this configuration provides, it is strongly suggested that you set\n')
         f.write('# up a proper instance of the full build system and use that instead.\n\n')
 
+        for line in newlines:
+            f.write(line)
+
         f.write('INHERIT += "%s"\n\n' % 'uninative')
         f.write('CONF_VERSION = "%s"\n\n' % d.getVar('CONF_VERSION'))
 
-- 
1.9.1