upload android base code part6

android/system/core/libcutils/klog.cpp

@@ -0,0 +1,69 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <cutils/android_get_control_file.h>
+#include <cutils/klog.h>
+
+static int klog_level = KLOG_INFO_LEVEL;
+
+void klog_set_level(int level) {
+    klog_level = level;
+}
+
+static int __open_klog(void) {
+    static const char kmsg_device[] = "/dev/kmsg";
+
+    int ret = android_get_control_file(kmsg_device);
+    if (ret >= 0) return ret;
+    return TEMP_FAILURE_RETRY(open(kmsg_device, O_WRONLY | O_CLOEXEC));
+}
+
+#define LOG_BUF_MAX 512
+
+void klog_writev(int level, const struct iovec* iov, int iov_count) {
+    if (level > klog_level) return;
+
+    static int klog_fd = __open_klog();
+    if (klog_fd == -1) return;
+    TEMP_FAILURE_RETRY(writev(klog_fd, iov, iov_count));
+}
+
+void klog_write(int level, const char* fmt, ...) {
+    if (level > klog_level) return;
+
+    char buf[LOG_BUF_MAX];
+    va_list ap;
+    va_start(ap, fmt);
+    vsnprintf(buf, sizeof(buf), fmt, ap);
+    va_end(ap);
+
+    buf[LOG_BUF_MAX - 1] = 0;
+
+    struct iovec iov[1];
+    iov[0].iov_base = buf;
+    iov[0].iov_len = strlen(buf);
+    klog_writev(level, iov, 1);
+}