bitbake: fetch2/wget: ensure all variables are set when calling urllib

Instead of just exporting the proxy variables when calling into urllib,
use bb.utils.environment() to export all of the known variables that are
needed for proper connectivity.

Specifically, this ensures that SSL_CERT_FILE is set, so that libssl can
find the certificates in buildtools environments

(Bitbake rev: 116637b0e9aabae7f680b102dbf3577b8a58f049)

Signed-off-by: Ross Burton <ross.burton@arm.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/fetch2/wget.py

@@ -282,19 +282,40 @@ class Wget(FetchMethod):
                 newreq = urllib.request.HTTPRedirectHandler.redirect_request(self, req, fp, code, msg, headers, newurl)
                 newreq.get_method = req.get_method
                 return newreq
-        exported_proxies = export_proxies(d)
 
-        handlers = [FixedHTTPRedirectHandler, HTTPMethodFallback]
-        if exported_proxies:
-            handlers.append(urllib.request.ProxyHandler())
-        handlers.append(CacheHTTPHandler())
-        # Since Python 2.7.9 ssl cert validation is enabled by default
-        # see PEP-0476, this causes verification errors on some https servers
-        # so disable by default.
-        import ssl
-        if hasattr(ssl, '_create_unverified_context'):
-            handlers.append(urllib.request.HTTPSHandler(context=ssl._create_unverified_context()))
-        opener = urllib.request.build_opener(*handlers)
+        # We need to update the environment here as both the proxy and HTTPS
+        # handlers need variables set. The proxy needs http_proxy and friends to
+        # be set, and HTTPSHandler ends up calling into openssl to load the
+        # certificates. In buildtools configurations this will be looking at the
+        # wrong place for certificates by default: we set SSL_CERT_FILE to the
+        # right location in the buildtools environment script but as BitBake
+        # prunes prunes the environment this is lost. When binaries are executed
+        # runfetchcmd ensures these values are in the environment, but this is
+        # pure Python so we need to update the environment.
+        #
+        # Avoid tramping the environment too much by using bb.utils.environment
+        # to scope the changes to the build_opener request, which is when the
+        # environment lookups happen.
+        newenv = {}
+        for name in bb.fetch2.FETCH_EXPORT_VARS:
+            value = d.getVar(name)
+            if not value:
+                origenv = d.getVar("BB_ORIGENV")
+                if origenv:
+                    value = origenv.getVar(name)
+            if value:
+                newenv[name] = value
+
+        with bb.utils.environment(**newenv):
+            import ssl
+
+            context = ssl._create_unverified_context()
+            handlers = [FixedHTTPRedirectHandler,
+                        HTTPMethodFallback,
+                        urllib.request.ProxyHandler(),
+                        CacheHTTPHandler(),
+                        urllib.request.HTTPSHandler(context=context)]
+            opener = urllib.request.build_opener(*handlers)
 
         try:
             uri = ud.url.split(";")[0]