From 682c34bbc32f3a9f007dd949282651ed35d4f6e3 Mon Sep 17 00:00:00 2001
From: Tao Bao <tbao@google.com>
Date: Tue, 7 Apr 2015 17:16:35 -0700
Subject: Rotate logs only when there are actual operations

Currently it rotates the log files every time it boots into the recovery
mode. We lose useful logs after ten times. This CL changes the rotation
condition so that it will rotate only if it performs some actual
operations that modify the flash (installs, wipes, sideloads and etc).

Bug: 19695622
Change-Id: Ie708ad955ef31aa500b6590c65faa72391705940
---
 adb_install.cpp |  2 ++
 common.h        |  1 +
 install.cpp     |  2 ++
 recovery.cpp    | 37 ++++++++++++++++++++++++++++---------
 4 files changed, 33 insertions(+), 9 deletions(-)

diff --git a/adb_install.cpp b/adb_install.cpp
index 6d6dbb165..ed15938e2 100644
--- a/adb_install.cpp
+++ b/adb_install.cpp
@@ -74,6 +74,8 @@ maybe_restart_adbd() {
 
 int
 apply_from_adb(RecoveryUI* ui_, bool* wipe_cache, const char* install_file) {
+    modified_flash = true;
+
     ui = ui_;
 
     stop_adbd();
diff --git a/common.h b/common.h
index 4f1c099df..b818ceb84 100644
--- a/common.h
+++ b/common.h
@@ -40,6 +40,7 @@ extern "C" {
 #define STRINGIFY(x) #x
 #define EXPAND(x) STRINGIFY(x)
 
+extern bool modified_flash;
 typedef struct fstab_rec Volume;
 
 // fopen a file, mounting volumes and making parent dirs as necessary.
diff --git a/install.cpp b/install.cpp
index 63b1d38c3..662f81c76 100644
--- a/install.cpp
+++ b/install.cpp
@@ -256,6 +256,8 @@ int
 install_package(const char* path, bool* wipe_cache, const char* install_file,
                 bool needs_mount)
 {
+    modified_flash = true;
+
     FILE* install_log = fopen_path(install_file, "w");
     if (install_log) {
         fputs(path, install_log);
diff --git a/recovery.cpp b/recovery.cpp
index 0ba4d1e27..2f8654a84 100644
--- a/recovery.cpp
+++ b/recovery.cpp
@@ -92,6 +92,7 @@ char* locale = NULL;
 char recovery_version[PROPERTY_VALUE_MAX+1];
 char* stage = NULL;
 char* reason = NULL;
+bool modified_flash = false;
 
 /*
  * The recovery tool communicates with the main system through /cache files.
@@ -337,13 +338,18 @@ copy_log_file(const char* source, const char* destination, int append) {
 
 // Rename last_log -> last_log.1 -> last_log.2 -> ... -> last_log.$max
 // Overwrites any existing last_log.$max.
-static void
-rotate_last_logs(int max) {
+static void rotate_last_logs(int max) {
+    // Logs should only be rotated once.
+    static bool rotated = false;
+    if (rotated) {
+        return;
+    }
+    rotated = true;
+    ensure_path_mounted(LAST_LOG_FILE);
+
     char oldfn[256];
     char newfn[256];
-
-    int i;
-    for (i = max-1; i >= 0; --i) {
+    for (int i = max-1; i >= 0; --i) {
         snprintf(oldfn, sizeof(oldfn), (i==0) ? LAST_LOG_FILE : (LAST_LOG_FILE ".%d"), i);
         snprintf(newfn, sizeof(newfn), LAST_LOG_FILE ".%d", i+1);
         // ignore errors
@@ -351,8 +357,17 @@ rotate_last_logs(int max) {
     }
 }
 
-static void
-copy_logs() {
+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
+    // or menu selections. This is to avoid unnecessary rotation (and
+    // possible deletion) of log files, if it does not do anything loggable.
+    if (!modified_flash) {
+        return;
+    }
+
+    rotate_last_logs(KEEP_LOG_COUNT);
+
     // Copy logs to cache so the system can find out what happened.
     copy_log_file(TEMPORARY_LOG_FILE, LOG_FILE, true);
     copy_log_file(TEMPORARY_LOG_FILE, LAST_LOG_FILE, false);
@@ -692,6 +707,8 @@ static bool wipe_data(int should_confirm, Device* device) {
         return false;
     }
 
+    modified_flash = true;
+
     ui->Print("\n-- Wiping data...\n");
     if (device->WipeData() == 0 && erase_volume("/data") == 0 && erase_volume("/cache") == 0) {
         ui->Print("Data wipe complete.\n");
@@ -708,6 +725,8 @@ static bool wipe_cache(bool should_confirm, Device* device) {
         return false;
     }
 
+    modified_flash = true;
+
     ui->Print("\n-- Wiping cache...\n");
     if (erase_volume("/cache") == 0) {
         ui->Print("Cache wipe complete.\n");
@@ -816,6 +835,8 @@ static void choose_recovery_file(Device* device) {
 }
 
 static int apply_from_sdcard(Device* device, bool* wipe_cache) {
+    modified_flash = true;
+
     if (ensure_path_mounted(SDCARD_ROOT) != 0) {
         ui->Print("\n-- Couldn't mount %s.\n", SDCARD_ROOT);
         return INSTALL_ERROR;
@@ -990,8 +1011,6 @@ main(int argc, char **argv) {
     printf("Starting recovery (pid %d) on %s", getpid(), ctime(&start));
 
     load_volume_table();
-    ensure_path_mounted(LAST_LOG_FILE);
-    rotate_last_logs(KEEP_LOG_COUNT);
     get_args(&argc, &argv);
 
     const char *send_intent = NULL;
-- 
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