Restrict pmsg use to eng builds.

bug 30375418

Change-Id: I50c6c74a2373593495cf6a3b94b31f9a865c950c

liblog/pmsg_writer.c

@@ -31,6 +31,8 @@
 #include <private/android_filesystem_config.h>
 #include <private/android_logger.h>
 
+#include <sys/system_properties.h>
+
 #include "config_write.h"
 #include "log_portability.h"
 #include "logger.h"
@@ -51,8 +53,25 @@ LIBLOG_HIDDEN struct android_log_transport_write pmsgLoggerWrite = {
     .write = pmsgWrite,
 };
 
+static bool pmsgShouldUse = false;
+
+// Only use pmsg on eng builds
+static bool pmsgIsEng() {
+    char buf[PROP_VALUE_MAX];
+
+    if (__system_property_get("ro.build.type", buf) == 0) {
+        return false;
+    }
+
+    if (!strncmp(buf, "eng", sizeof("eng"))) {
+        return true;
+    }
+    return false;
+}
+
 static int pmsgOpen()
 {
+    pmsgShouldUse = pmsgIsEng();
     if (pmsgLoggerWrite.context.fd < 0) {
         pmsgLoggerWrite.context.fd = TEMP_FAILURE_RETRY(open("/dev/pmsg0", O_WRONLY | O_CLOEXEC));
     }
@@ -75,7 +94,7 @@ static int pmsgAvailable(log_id_t logId)
     }
     if ((logId != LOG_ID_SECURITY) &&
             (logId != LOG_ID_EVENTS) &&
-            !__android_log_is_debuggable()) {
+            (!pmsgShouldUse || !__android_log_is_debuggable())) {
         return -EINVAL;
     }
     if (pmsgLoggerWrite.context.fd < 0) {
@@ -105,7 +124,7 @@ static int pmsgWrite(log_id_t logId, struct timespec *ts,
     size_t i, payloadSize;
     ssize_t ret;
 
-    if ((logId == LOG_ID_EVENTS) && !__android_log_is_debuggable()) {
+    if ((logId == LOG_ID_EVENTS) && (!pmsgShouldUse || !__android_log_is_debuggable())) {
         if (vec[0].iov_len < 4) {
             return -EINVAL;
         }