RFC - Various bug fixes for android_os_SELinux.cpp

[Richard Haines]

I've been attempting to test some networking and had problems with
SELinux.getPeerContext when no context set using java.net.Socket - the app
aborts. This patch fixes the two problems in getPeerCon. I've also patched
the other get... methods/functions to set the initial pointer to null and
give the error.

Does this seem reasonable.

Richard
--- a/android_os_SELinux.cpp	2013-05-21 19:00:37.589485000 +0100
+++ b/android_os_SELinux.cpp	2013-05-21 19:45:40.208768298 +0100
@@ -102,16 +102,18 @@
         return NULL;
     }
 
-    security_context_t tmp;
+    security_context_t tmp = NULL;
     int ret = getpeercon(fd, &tmp);
     Unique_SecurityContext context(tmp);
 
     ScopedLocalRef<jstring> contextStr(env, NULL);
     if (ret != -1) {
         contextStr.reset(env->NewStringUTF(context.get()));
+    } else {
+        ALOGE("getPeerCon error: %s (errno %d)", strerror(errno), errno);
     }
 
-    ALOGV("getPeerCon(%d) => %s", fd, contextStr.get());
+    ALOGV("getPeerCon(%d) => %s", fd, context.get());
     return contextStr.release();
 }
 
@@ -198,13 +200,15 @@
         return NULL;
     }
 
-    security_context_t tmp;
+    security_context_t tmp = NULL;
     int ret = getfilecon(path.c_str(), &tmp);
     Unique_SecurityContext context(tmp);
 
     ScopedLocalRef<jstring> securityString(env, NULL);
     if (ret != -1) {
         securityString.reset(env->NewStringUTF(context.get()));
+    } else {
+        ALOGE("getFileCon error: %s (errno %d)", strerror(errno), errno);
     }
 
     ALOGV("getFileCon(%s) => %s", path.c_str(), context.get());
@@ -224,13 +228,15 @@
         return NULL;
     }
 
-    security_context_t tmp;
+    security_context_t tmp = NULL;
     int ret = getcon(&tmp);
     Unique_SecurityContext context(tmp);
 
     ScopedLocalRef<jstring> securityString(env, NULL);
     if (ret != -1) {
         securityString.reset(env->NewStringUTF(context.get()));
+    } else {
+        ALOGE("getCon error: %s (errno %d)", strerror(errno), errno);
     }
 
     ALOGV("getCon() => %s", context.get());
@@ -251,13 +257,15 @@
         return NULL;
     }
 
-    security_context_t tmp;
+    security_context_t tmp = NULL;
     int ret = getpidcon(static_cast<pid_t>(pid), &tmp);
     Unique_SecurityContext context(tmp);
 
     ScopedLocalRef<jstring> securityString(env, NULL);
     if (ret != -1) {
         securityString.reset(env->NewStringUTF(context.get()));
+    } else {
+        ALOGE("getPidCon error: %s (errno %d)", strerror(errno), errno);
     }
 
     ALOGV("getPidCon(%d) => %s", pid, context.get());