1 files changed, 115 insertions, 0 deletions

diff --git a/rotate_logs.cpp b/rotate_logs.cpp
new file mode 100644
index 000000000..fc220215e
--- /dev/null
+++ b/rotate_logs.cpp
@@ -0,0 +1,115 @@
+/*
+ * Copyright (C) 2016 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 "rotate_logs.h"
+
+#include <stdio.h>
+#include <string.h>
+#include <sys/types.h>
+
+#include <string>
+
+#include <android-base/file.h>
+#include <android-base/logging.h>
+#include <android-base/parseint.h>
+#include <android-base/stringprintf.h>
+#include <private/android_logger.h> /* private pmsg functions */
+
+static const std::string LAST_KMSG_FILTER = "recovery/last_kmsg";
+static const std::string LAST_LOG_FILTER = "recovery/last_log";
+
+ssize_t logbasename(
+        log_id_t /* logId */,
+        char /* prio */,
+        const char *filename,
+        const char * /* buf */, size_t len,
+        void *arg) {
+    bool* doRotate  = static_cast<bool*>(arg);
+    if (LAST_KMSG_FILTER.find(filename) != std::string::npos ||
+            LAST_LOG_FILTER.find(filename) != std::string::npos) {
+        *doRotate = true;
+    }
+    return len;
+}
+
+ssize_t logrotate(
+        log_id_t logId,
+        char prio,
+        const char *filename,
+        const char *buf, size_t len,
+        void *arg) {
+    bool* doRotate  = static_cast<bool*>(arg);
+    if (!*doRotate) {
+        return __android_log_pmsg_file_write(logId, prio, filename, buf, len);
+    }
+
+    std::string name(filename);
+    size_t dot = name.find_last_of('.');
+    std::string sub = name.substr(0, dot);
+
+    if (LAST_KMSG_FILTER.find(sub) == std::string::npos &&
+            LAST_LOG_FILTER.find(sub) == std::string::npos) {
+        return __android_log_pmsg_file_write(logId, prio, filename, buf, len);
+    }
+
+    // filename rotation
+    if (dot == std::string::npos) {
+        name += ".1";
+    } else {
+        std::string number = name.substr(dot + 1);
+        if (!isdigit(number[0])) {
+            name += ".1";
+        } else {
+            size_t i;
+            if (!android::base::ParseUint(number, &i)) {
+                LOG(ERROR) << "failed to parse uint in " << number;
+                return -1;
+            }
+            name = sub + "." + std::to_string(i + 1);
+        }
+    }
+
+    return __android_log_pmsg_file_write(logId, prio, name.c_str(), buf, len);
+}
+
+// Rename last_log -> last_log.1 -> last_log.2 -> ... -> last_log.$max.
+// Similarly rename last_kmsg -> last_kmsg.1 -> ... -> last_kmsg.$max.
+// Overwrite any existing last_log.$max and last_kmsg.$max.
+void rotate_logs(const char* last_log_file, const char* last_kmsg_file) {
+    // Logs should only be rotated once.
+    static bool rotated = false;
+    if (rotated) {
+        return;
+    }
+    rotated = true;
+
+    for (int i = KEEP_LOG_COUNT - 1; i >= 0; --i) {
+        std::string old_log = android::base::StringPrintf("%s", last_log_file);
+        if (i > 0) {
+          old_log += "." + std::to_string(i);
+        }
+        std::string new_log = android::base::StringPrintf("%s.%d", last_log_file, i+1);
+        // Ignore errors if old_log doesn't exist.
+        rename(old_log.c_str(), new_log.c_str());
+
+        std::string old_kmsg = android::base::StringPrintf("%s", last_kmsg_file);
+        if (i > 0) {
+          old_kmsg += "." + std::to_string(i);
+        }
+        std::string new_kmsg = android::base::StringPrintf("%s.%d", last_kmsg_file, i+1);
+        rename(old_kmsg.c_str(), new_kmsg.c_str());
+    }
+}