diff --git a/Android.mk b/Android.mk
index 2a3438f..4a7afb7 100644
--- a/Android.mk
+++ b/Android.mk
@@ -46,6 +46,7 @@
     install.cpp \
     recovery.cpp \
     roots.cpp \
+    rotate_logs.cpp \
     screen_ui.cpp \
     ui.cpp \
     verifier.cpp \
@@ -119,7 +120,9 @@
 # recovery-persist (system partition dynamic executable run after /data mounts)
 # ===============================
 include $(CLEAR_VARS)
-LOCAL_SRC_FILES := recovery-persist.cpp
+LOCAL_SRC_FILES := \
+    recovery-persist.cpp \
+    rotate_logs.cpp
 LOCAL_MODULE := recovery-persist
 LOCAL_SHARED_LIBRARIES := liblog libbase
 LOCAL_CFLAGS := -Werror
@@ -129,9 +132,11 @@
 # recovery-refresh (system partition dynamic executable run at init)
 # ===============================
 include $(CLEAR_VARS)
-LOCAL_SRC_FILES := recovery-refresh.cpp
+LOCAL_SRC_FILES := \
+    recovery-refresh.cpp \
+    rotate_logs.cpp
 LOCAL_MODULE := recovery-refresh
-LOCAL_SHARED_LIBRARIES := liblog
+LOCAL_SHARED_LIBRARIES := liblog libbase
 LOCAL_CFLAGS := -Werror
 LOCAL_INIT_RC := recovery-refresh.rc
 include $(BUILD_EXECUTABLE)
diff --git a/common.h b/common.h
index a948fb1..319af3d 100644
--- a/common.h
+++ b/common.h
@@ -17,15 +17,22 @@
 #ifndef RECOVERY_COMMON_H
 #define RECOVERY_COMMON_H
 
-#include <stdbool.h>
 #include <stdio.h>
 #include <stdarg.h>
 
 #define STRINGIFY(x) #x
 #define EXPAND(x) STRINGIFY(x)
 
+class RecoveryUI;
+
+extern RecoveryUI* ui;
 extern bool modified_flash;
-typedef struct fstab_rec Volume;
+
+// The current stage, e.g. "1/2".
+extern const char* stage;
+
+// The reason argument provided in "--reason=".
+extern const char* reason;
 
 // fopen a file, mounting volumes and making parent dirs as necessary.
 FILE* fopen_path(const char *path, const char *mode);
diff --git a/install.cpp b/install.cpp
index 0f9088a..3871271 100644
--- a/install.cpp
+++ b/install.cpp
@@ -43,8 +43,6 @@
 #include "ui.h"
 #include "verifier.h"
 
-extern RecoveryUI* ui;
-
 #define ASSUMED_UPDATE_BINARY_NAME  "META-INF/com/google/android/update-binary"
 #define PUBLIC_KEYS_FILE "/res/keys"
 static constexpr const char* METADATA_PATH = "META-INF/com/android/metadata";
diff --git a/install.h b/install.h
index 7f66a51..1ec01e8 100644
--- a/install.h
+++ b/install.h
@@ -20,10 +20,9 @@
 #include <string>
 #include <ziparchive/zip_archive.h>
 
-#include "common.h"
-
 enum { INSTALL_SUCCESS, INSTALL_ERROR, INSTALL_CORRUPT, INSTALL_NONE, INSTALL_SKIPPED,
         INSTALL_RETRY };
+
 // Install the package specified by root_path.  If INSTALL_SUCCESS is
 // returned and *wipe_cache is true on exit, caller should wipe the
 // cache partition.
diff --git a/print_sha1.h b/print_sha1.h
index c7c1f36..1f85895 100644
--- a/print_sha1.h
+++ b/print_sha1.h
@@ -20,7 +20,7 @@
 #include <stdint.h>
 #include <string>
 
-#include "openssl/sha.h"
+#include <openssl/sha.h>
 
 static std::string print_sha1(const uint8_t* sha1, size_t len) {
     const char* hex = "0123456789abcdef";
@@ -41,7 +41,7 @@
 }
 
 static std::string print_hex(const uint8_t* bytes, size_t len) {
-  return print_sha1(bytes, len);
+    return print_sha1(bytes, len);
 }
 
 #endif  // RECOVERY_PRINT_SHA1_H
diff --git a/recovery-persist.cpp b/recovery-persist.cpp
index b0ec141..d706cca 100644
--- a/recovery-persist.cpp
+++ b/recovery-persist.cpp
@@ -30,7 +30,6 @@
 //    --force-persist  ignore /cache mount, always rotate in the contents.
 //
 
-#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -40,17 +39,16 @@
 
 #include <android-base/file.h>
 #include <android-base/logging.h>
-
 #include <private/android_logger.h> /* private pmsg functions */
 
+#include "rotate_logs.h"
+
 static const char *LAST_LOG_FILE = "/data/misc/recovery/last_log";
 static const char *LAST_PMSG_FILE = "/sys/fs/pstore/pmsg-ramoops-0";
 static const char *LAST_KMSG_FILE = "/data/misc/recovery/last_kmsg";
 static const char *LAST_CONSOLE_FILE = "/sys/fs/pstore/console-ramoops-0";
 static const char *ALT_LAST_CONSOLE_FILE = "/sys/fs/pstore/console-ramoops";
 
-static const int KEEP_LOG_COUNT = 10;
-
 // close a file, log an error if the error indicator is set
 static void check_and_fclose(FILE *fp, const char *name) {
     fflush(fp);
@@ -80,39 +78,6 @@
 
 static bool rotated = false;
 
-// 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.
-static void rotate_logs(int max) {
-    // Logs should only be rotated once.
-
-    if (rotated) {
-        return;
-    }
-    rotated = true;
-
-    for (int i = max-1; i >= 0; --i) {
-        std::string old_log(LAST_LOG_FILE);
-        if (i > 0) {
-          old_log += "." + std::to_string(i);
-        }
-        std::string new_log(LAST_LOG_FILE);
-        new_log += "." + std::to_string(i+1);
-
-        // Ignore errors if old_log doesn't exist.
-        rename(old_log.c_str(), new_log.c_str());
-
-        std::string old_kmsg(LAST_KMSG_FILE);
-        if (i > 0) {
-          old_kmsg += "." + std::to_string(i);
-        }
-        std::string new_kmsg(LAST_KMSG_FILE);
-        new_kmsg += "." + std::to_string(i+1);
-
-        rename(old_kmsg.c_str(), new_kmsg.c_str());
-    }
-}
-
 ssize_t logsave(
         log_id_t /* logId */,
         char /* prio */,
@@ -138,7 +103,8 @@
     // already-rotated files? Algorithm thus far is KISS: one file,
     // one rotation allowed.
 
-    rotate_logs(KEEP_LOG_COUNT);
+    rotate_logs(LAST_LOG_FILE, LAST_KMSG_FILE);
+    rotated = true;
 
     return android::base::WriteStringToFile(buffer, destination.c_str());
 }
diff --git a/recovery-refresh.cpp b/recovery-refresh.cpp
index b2ab52f..14565d3 100644
--- a/recovery-refresh.cpp
+++ b/recovery-refresh.cpp
@@ -14,8 +14,6 @@
  * limitations under the License.
  */
 
-#define LOG_TAG "recovery-refresh"
-
 //
 // Strictly to deal with reboot into system after OTA, then
 // reboot while in system before boot complete landing us back
@@ -40,64 +38,11 @@
 //
 
 #include <string.h>
-
 #include <string>
 
-#include <android/log.h> /* Android Log Priority Tags */
 #include <private/android_logger.h> /* private pmsg functions */
 
-static const char LAST_KMSG_FILE[] = "recovery/last_kmsg";
-static const char LAST_LOG_FILE[] = "recovery/last_log";
-
-static ssize_t logbasename(
-        log_id_t /* logId */,
-        char /* prio */,
-        const char *filename,
-        const char * /* buf */, size_t len,
-        void *arg) {
-    if (strstr(LAST_KMSG_FILE, filename) ||
-            strstr(LAST_LOG_FILE, filename)) {
-        bool *doRotate = reinterpret_cast<bool *>(arg);
-        *doRotate = true;
-    }
-    return len;
-}
-
-static ssize_t logrotate(
-        log_id_t logId,
-        char prio,
-        const char *filename,
-        const char *buf, size_t len,
-        void *arg) {
-    bool *doRotate = reinterpret_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 (!strstr(LAST_KMSG_FILE, sub.c_str()) &&
-                !strstr(LAST_LOG_FILE, sub.c_str())) {
-        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.data()[0])) {
-            name += ".1";
-        } else {
-            auto i = std::stoull(number);
-            name = sub + "." + std::to_string(i + 1);
-        }
-    }
-
-    return __android_log_pmsg_file_write(logId, prio, name.c_str(), buf, len);
-}
+#include "rotate_logs.h"
 
 int main(int argc, char **argv) {
     static const char filter[] = "recovery/";
@@ -105,7 +50,6 @@
     static const char rotate_flag[] = "--rotate";
     ssize_t ret;
     bool doRotate = false;
-
     // Take last pmsg contents and rewrite it to the current pmsg session.
     if ((argc <= 1) || !argv[1] ||
             (((doRotate = strcmp(argv[1], rotate_flag))) &&
diff --git a/recovery.cpp b/recovery.cpp
index 4d1ad1d..02d460e 100644
--- a/recovery.cpp
+++ b/recovery.cpp
@@ -66,10 +66,9 @@
 #include "minui/minui.h"
 #include "otautil/DirUtil.h"
 #include "roots.h"
-#include "ui.h"
+#include "rotate_logs.h"
 #include "screen_ui.h"
-
-struct selabel_handle *sehandle;
+#include "ui.h"
 
 static const struct option OPTIONS[] = {
   { "update_package", required_argument, NULL, 'u' },
@@ -110,7 +109,6 @@
 static const char *TEMPORARY_INSTALL_FILE = "/tmp/last_install";
 static const char *LAST_KMSG_FILE = "/cache/recovery/last_kmsg";
 static const char *LAST_LOG_FILE = "/cache/recovery/last_log";
-static const int KEEP_LOG_COUNT = 10;
 // We will try to apply the update package 5 times at most in case of an I/O error.
 static const int EIO_RETRY_COUNT = 4;
 static const int BATTERY_READ_TIMEOUT_IN_SEC = 10;
@@ -119,15 +117,18 @@
 // So we should check battery with a slightly lower limitation.
 static const int BATTERY_OK_PERCENTAGE = 20;
 static const int BATTERY_WITH_CHARGER_OK_PERCENTAGE = 15;
-constexpr const char* RECOVERY_WIPE = "/etc/recovery.wipe";
+static constexpr const char* RECOVERY_WIPE = "/etc/recovery.wipe";
+static constexpr const char* DEFAULT_LOCALE = "en_US";
 
-RecoveryUI* ui = NULL;
-static const char* locale = "en_US";
-char* stage = NULL;
-char* reason = NULL;
-bool modified_flash = false;
+static std::string locale;
 static bool has_cache = false;
 
+RecoveryUI* ui = nullptr;
+bool modified_flash = false;
+const char* stage = nullptr;
+const char* reason = nullptr;
+struct selabel_handle* sehandle;
+
 /*
  * The recovery tool communicates with the main system through /cache files.
  *   /cache/recovery/command - INPUT - command line for tool, one arg per line
@@ -206,6 +207,9 @@
 // close a file, log an error if the error indicator is set
 static void check_and_fclose(FILE *fp, const char *name) {
     fflush(fp);
+    if (fsync(fileno(fp)) == -1) {
+        PLOG(ERROR) << "Failed to fsync " << name;
+    }
     if (ferror(fp)) {
         PLOG(ERROR) << "Error in " << name;
     }
@@ -447,37 +451,6 @@
     }
 }
 
-// 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.
-static void rotate_logs(int max) {
-    // Logs should only be rotated once.
-    static bool rotated = false;
-    if (rotated) {
-        return;
-    }
-    rotated = true;
-    ensure_path_mounted(LAST_LOG_FILE);
-    ensure_path_mounted(LAST_KMSG_FILE);
-
-    for (int i = max-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());
-    }
-}
-
 static void copy_logs() {
     // We only rotate and record the log of the current session if there are
     // actual attempts to modify the flash, such as wipes, installs from BCB
@@ -496,7 +469,9 @@
         return;
     }
 
-    rotate_logs(KEEP_LOG_COUNT);
+    ensure_path_mounted(LAST_LOG_FILE);
+    ensure_path_mounted(LAST_KMSG_FILE);
+    rotate_logs(LAST_LOG_FILE, LAST_KMSG_FILE);
 
     // Copy logs to cache so the system can find out what happened.
     copy_log_file(TEMPORARY_LOG_FILE, LOG_FILE, true);
@@ -515,24 +490,18 @@
 // clear the recovery command and prepare to boot a (hopefully working) system,
 // copy our log file to cache as well (for the system to read). This function is
 // idempotent: call it as many times as you like.
-static void
-finish_recovery() {
+static void finish_recovery() {
     // Save the locale to cache, so if recovery is next started up
     // without a --locale argument (eg, directly from the bootloader)
     // it will use the last-known locale.
-    if (locale != NULL) {
-        size_t len = strlen(locale);
-        __pmsg_write(LOCALE_FILE, locale, len);
-        if (has_cache) {
-            LOG(INFO) << "Saving locale \"" << locale << "\"";
-            FILE* fp = fopen_path(LOCALE_FILE, "w");
-            if (fp != NULL) {
-                fwrite(locale, 1, len, fp);
-                fflush(fp);
-                fsync(fileno(fp));
-                check_and_fclose(fp, LOCALE_FILE);
-            }
+    if (!locale.empty() && has_cache) {
+        LOG(INFO) << "Saving locale \"" << locale << "\"";
+
+        FILE* fp = fopen_path(LOCALE_FILE, "w");
+        if (!android::base::WriteStringToFd(locale, fileno(fp))) {
+            PLOG(ERROR) << "Failed to save locale to " << LOCALE_FILE;
         }
+        check_and_fclose(fp, LOCALE_FILE);
     }
 
     copy_logs();
@@ -1282,40 +1251,32 @@
     printf("%s=%s\n", key, name);
 }
 
-static void
-load_locale_from_cache() {
-    FILE* fp = fopen_path(LOCALE_FILE, "r");
-    char buffer[80];
-    if (fp != NULL) {
-        fgets(buffer, sizeof(buffer), fp);
-        int j = 0;
-        unsigned int i;
-        for (i = 0; i < sizeof(buffer) && buffer[i]; ++i) {
-            if (!isspace(buffer[i])) {
-                buffer[j++] = buffer[i];
-            }
-        }
-        buffer[j] = 0;
-        locale = strdup(buffer);
-        check_and_fclose(fp, LOCALE_FILE);
+static std::string load_locale_from_cache() {
+    if (ensure_path_mounted(LOCALE_FILE) != 0) {
+        LOG(ERROR) << "Can't mount " << LOCALE_FILE;
+        return "";
     }
+
+    std::string content;
+    if (!android::base::ReadFileToString(LOCALE_FILE, &content)) {
+        PLOG(ERROR) << "Can't read " << LOCALE_FILE;
+        return "";
+    }
+
+    return android::base::Trim(content);
 }
 
-static RecoveryUI* gCurrentUI = NULL;
-
-void
-ui_print(const char* format, ...) {
-    char buffer[256];
-
+void ui_print(const char* format, ...) {
+    std::string buffer;
     va_list ap;
     va_start(ap, format);
-    vsnprintf(buffer, sizeof(buffer), format, ap);
+    android::base::StringAppendV(&buffer, format, ap);
     va_end(ap);
 
-    if (gCurrentUI != NULL) {
-        gCurrentUI->Print("%s", buffer);
+    if (ui != nullptr) {
+        ui->Print("%s", buffer.c_str());
     } else {
-        fputs(buffer, stdout);
+        fputs(buffer.c_str(), stdout);
     }
 }
 
@@ -1324,8 +1285,8 @@
 void UiLogger(android::base::LogId id, android::base::LogSeverity severity,
                const char* tag, const char* file, unsigned int line,
                const char* message) {
-    if (severity >= android::base::ERROR && gCurrentUI != NULL) {
-        gCurrentUI->Print("E:%s\n", message);
+    if (severity >= android::base::ERROR && ui != nullptr) {
+        ui->Print("E:%s\n", message);
     } else {
         fprintf(stdout, "%c:%s\n", log_characters[severity], message);
     }
@@ -1421,63 +1382,13 @@
     };
     std::string log_content = android::base::Join(log_buffer, "\n");
     if (!android::base::WriteStringToFile(log_content, TEMPORARY_INSTALL_FILE)) {
-      PLOG(ERROR) << "failed to write " << TEMPORARY_INSTALL_FILE;
+        PLOG(ERROR) << "failed to write " << TEMPORARY_INSTALL_FILE;
     }
 
     // Also write the info into last_log.
     LOG(INFO) << log_content;
 }
 
-static ssize_t logbasename(
-        log_id_t /* logId */,
-        char /* prio */,
-        const char *filename,
-        const char * /* buf */, size_t len,
-        void *arg) {
-    if (strstr(LAST_KMSG_FILE, filename) ||
-            strstr(LAST_LOG_FILE, filename)) {
-        bool *doRotate = reinterpret_cast<bool *>(arg);
-        *doRotate = true;
-    }
-    return len;
-}
-
-static ssize_t logrotate(
-        log_id_t logId,
-        char prio,
-        const char *filename,
-        const char *buf, size_t len,
-        void *arg) {
-    bool *doRotate = reinterpret_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 (!strstr(LAST_KMSG_FILE, sub.c_str()) &&
-                !strstr(LAST_LOG_FILE, sub.c_str())) {
-        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.data()[0])) {
-            name += ".1";
-        } else {
-            auto i = std::stoull(number);
-            name = sub + "." + std::to_string(i + 1);
-        }
-    }
-
-    return __android_log_pmsg_file_write(logId, prio, name.c_str(), buf, len);
-}
-
 int main(int argc, char **argv) {
     // We don't have logcat yet under recovery; so we'll print error on screen and
     // log to stdout (which is redirected to recovery.log) as we used to do.
@@ -1487,6 +1398,7 @@
     static const char filter[] = "recovery/";
     // Do we need to rotate?
     bool doRotate = false;
+
     __android_log_pmsg_file_read(
         LOG_ID_SYSTEM, ANDROID_LOG_INFO, filter,
         logbasename, &doRotate);
@@ -1573,18 +1485,24 @@
         }
     }
 
-    if (locale == nullptr && has_cache) {
-        load_locale_from_cache();
+    if (locale.empty()) {
+        if (has_cache) {
+            locale = load_locale_from_cache();
+        }
+
+        if (locale.empty()) {
+            locale = DEFAULT_LOCALE;
+        }
     }
-    printf("locale is [%s]\n", locale);
+
+    printf("locale is [%s]\n", locale.c_str());
     printf("stage is [%s]\n", stage);
     printf("reason is [%s]\n", reason);
 
     Device* device = make_device();
     ui = device->GetUI();
-    gCurrentUI = ui;
 
-    ui->SetLocale(locale);
+    ui->SetLocale(locale.c_str());
     ui->Init();
     // Set background string to "installing security update" for security update,
     // otherwise set it to "installing system update".
@@ -1599,7 +1517,7 @@
     if (show_text) ui->ShowText(true);
 
     struct selinux_opt seopts[] = {
-      { SELABEL_OPT_PATH, "/file_contexts" }
+        { SELABEL_OPT_PATH, "/file_contexts" }
     };
 
     sehandle = selabel_open(SELABEL_CTX_FILE, seopts, 1);
@@ -1771,7 +1689,7 @@
             break;
     }
     while (true) {
-      pause();
+        pause();
     }
     // Should be unreachable.
     return EXIT_SUCCESS;
diff --git a/roots.h b/roots.h
index a14b7d9..542f03b 100644
--- a/roots.h
+++ b/roots.h
@@ -17,7 +17,7 @@
 #ifndef RECOVERY_ROOTS_H_
 #define RECOVERY_ROOTS_H_
 
-#include "common.h"
+typedef struct fstab_rec Volume;
 
 // Load and parse volume data from /etc/recovery.fstab.
 void load_volume_table();
diff --git a/rotate_logs.cpp b/rotate_logs.cpp
new file mode 100644
index 0000000..fc22021
--- /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());
+    }
+}
diff --git a/rotate_logs.h b/rotate_logs.h
new file mode 100644
index 0000000..809c213
--- /dev/null
+++ b/rotate_logs.h
@@ -0,0 +1,44 @@
+/*
+ * 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.
+ */
+
+#ifndef _ROTATE_LOGS_H
+#define _ROTATE_LOGS_H
+
+#include <string>
+
+#include <private/android_logger.h> /* private pmsg functions */
+
+constexpr int KEEP_LOG_COUNT = 10;
+
+ssize_t logbasename(log_id_t /* logId */,
+        char /* prio */,
+        const char *filename,
+        const char * /* buf */, size_t len,
+        void *arg);
+
+ssize_t logrotate(
+        log_id_t logId,
+        char prio,
+        const char *filename,
+        const char *buf, size_t len,
+        void *arg);
+
+// 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);
+
+#endif //_ROTATE_LOG_H
diff --git a/verifier.cpp b/verifier.cpp
index 82cdd3b..44098f7 100644
--- a/verifier.cpp
+++ b/verifier.cpp
@@ -14,9 +14,11 @@
  * limitations under the License.
  */
 
+#include "verifier.h"
+
 #include <errno.h>
-#include <malloc.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
 
 #include <algorithm>
@@ -31,9 +33,6 @@
 #include "common.h"
 #include "print_sha1.h"
 #include "ui.h"
-#include "verifier.h"
-
-extern RecoveryUI* ui;
 
 static constexpr size_t MiB = 1024 * 1024;