diff --git a/liblog/Android.mk b/liblog/Android.mk
index c18dc48..4fe20db 100644
--- a/liblog/Android.mk
+++ b/liblog/Android.mk
@@ -22,6 +22,10 @@
 liblog_sources := logd_write_kern.c
 endif
 
+ifneq ($(filter userdebug eng,$(TARGET_BUILD_VARIANT)),)
+liblog_cflags := -DUSERDEBUG_BUILD=1
+endif
+
 # some files must not be compiled when building against Mingw
 # they correspond to features not used by our host development tools
 # which are also hard or even impossible to port to native Win32
@@ -80,11 +84,13 @@
 include $(CLEAR_VARS)
 LOCAL_MODULE := liblog
 LOCAL_SRC_FILES := $(liblog_target_sources)
+LOCAL_CFLAGS := $(liblog_cflags)
 include $(BUILD_STATIC_LIBRARY)
 
 include $(CLEAR_VARS)
 LOCAL_MODULE := liblog
 LOCAL_WHOLE_STATIC_LIBRARIES := liblog
+LOCAL_CFLAGS := $(liblog_cflags)
 include $(BUILD_SHARED_LIBRARY)
 
 include $(call first-makefiles-under,$(LOCAL_PATH))
diff --git a/liblog/log_read.c b/liblog/log_read.c
index 6f6fe5f..e4acac2 100644
--- a/liblog/log_read.c
+++ b/liblog/log_read.c
@@ -296,11 +296,8 @@
     return ret;
 }
 
-int android_logger_clear(struct logger *logger)
+static int check_log_success(char *buf, ssize_t ret)
 {
-    char buf[512];
-
-    ssize_t ret = send_log_msg(logger, "clear %d", buf, sizeof(buf));
     if (ret < 0) {
         return ret;
     }
@@ -312,8 +309,16 @@
     return 0;
 }
 
+int android_logger_clear(struct logger *logger)
+{
+    char buf[512];
+
+    return check_log_success(buf,
+        send_log_msg(logger, "clear %d", buf, sizeof(buf)));
+}
+
 /* returns the total size of the log's ring buffer */
-int android_logger_get_log_size(struct logger *logger)
+long android_logger_get_log_size(struct logger *logger)
 {
     char buf[512];
 
@@ -326,14 +331,28 @@
         return -1;
     }
 
-    return atoi(buf);
+    return atol(buf);
 }
 
+#ifdef USERDEBUG_BUILD
+
+int android_logger_set_log_size(struct logger *logger, unsigned long size)
+{
+    char buf[512];
+
+    snprintf(buf, sizeof(buf), "setLogSize %d %lu",
+        logger ? logger->id : (unsigned) -1, size);
+
+    return check_log_success(buf, send_log_msg(NULL, NULL, buf, sizeof(buf)));
+}
+
+#endif /* USERDEBUG_BUILD */
+
 /*
  * returns the readable size of the log's ring buffer (that is, amount of the
  * log consumed)
  */
-int android_logger_get_log_readable_size(struct logger *logger)
+long android_logger_get_log_readable_size(struct logger *logger)
 {
     char buf[512];
 
@@ -346,7 +365,7 @@
         return -1;
     }
 
-    return atoi(buf);
+    return atol(buf);
 }
 
 /*
@@ -383,6 +402,32 @@
     return send_log_msg(NULL, NULL, buf, len);
 }
 
+#ifdef USERDEBUG_BUILD
+
+ssize_t android_logger_get_prune_list(struct logger_list *logger_list UNUSED,
+                                      char *buf, size_t len)
+{
+    return send_log_msg(NULL, "getPruneList", buf, len);
+}
+
+int android_logger_set_prune_list(struct logger_list *logger_list UNUSED,
+                                  char *buf, size_t len)
+{
+    const char cmd[] = "setPruneList ";
+    const size_t cmdlen = sizeof(cmd) - 1;
+
+    if (strlen(buf) > (len - cmdlen)) {
+        return -ENOMEM; /* KISS */
+    }
+    memmove(buf + cmdlen, buf, len - cmdlen);
+    buf[len - 1] = '\0';
+    memcpy(buf, cmd, cmdlen);
+
+    return check_log_success(buf, send_log_msg(NULL, NULL, buf, len));
+}
+
+#endif /* USERDEBUG_BUILD */
+
 struct logger_list *android_logger_list_alloc(int mode,
                                               unsigned int tail,
                                               pid_t pid)
diff --git a/liblog/log_read_kern.c b/liblog/log_read_kern.c
index 59a7a0b..483b6b6 100644
--- a/liblog/log_read_kern.c
+++ b/liblog/log_read_kern.c
@@ -227,16 +227,26 @@
 }
 
 /* returns the total size of the log's ring buffer */
-int android_logger_get_log_size(struct logger *logger)
+long android_logger_get_log_size(struct logger *logger)
 {
     return logger_ioctl(logger, LOGGER_GET_LOG_BUF_SIZE, O_RDWR);
 }
 
+#ifdef USERDEBUG_BUILD
+
+int android_logger_set_log_size(struct logger *logger UNUSED,
+                                unsigned long size UNUSED)
+{
+    return -ENOTSUP;
+}
+
+#endif /* USERDEBUG_BUILD */
+
 /*
  * returns the readable size of the log's ring buffer (that is, amount of the
  * log consumed)
  */
-int android_logger_get_log_readable_size(struct logger *logger)
+long android_logger_get_log_readable_size(struct logger *logger)
 {
     return logger_ioctl(logger, LOGGER_GET_LOG_LEN, O_RDONLY);
 }
@@ -253,15 +263,34 @@
 /*
  * returns statistics
  */
+static const char unsupported[] = "18\nNot Supported\n\f";
 
 ssize_t android_logger_get_statistics(struct logger_list *logger_list UNUSED,
                                       char *buf, size_t len)
 {
-    static const char unsupported[] = "18\nNot Supported\n\f";
     strncpy(buf, unsupported, len);
     return -ENOTSUP;
 }
 
+#ifdef USERDEBUG_BUILD
+
+ssize_t android_logger_get_prune_list(struct logger_list *logger_list UNUSED,
+                                      char *buf, size_t len)
+{
+    strncpy(buf, unsupported, len);
+    return -ENOTSUP;
+}
+
+int android_logger_set_prune_list(struct logger_list *logger_list UNUSED,
+                                  char *buf, size_t len)
+{
+    static const char unsupported_error[] = "Unsupported";
+    strncpy(buf, unsupported, len);
+    return -ENOTSUP;
+}
+
+#endif /* USERDEBUG_BUILD */
+
 struct logger_list *android_logger_list_alloc(int mode,
                                               unsigned int tail,
                                               pid_t pid)