[core] Dump fd if log file deleted (#1337)

core/src/main/cpp/daemon/logcat.cpp

@@ -5,7 +5,6 @@
 #include <array>
 #include <cinttypes>
 #include "logcat.h"
-#include <string_view>
 #include <sys/system_properties.h>
 
 using namespace std::string_view_literals;
@@ -88,14 +87,16 @@ size_t Logcat::PrintLogLine(const AndroidLogEntry &entry, FILE *out) {
     }
     localtime_r(&now, &tm);
     strftime(time_buff.data(), time_buff.size(), "%Y-%m-%dT%H:%M:%S", &tm);
-    // implicitly convert to size_t and intentionally trigger overflow when failed
-    // to generate a new fd
-    return fprintf(out, "[ %s.%03ld %8d:%6d:%6d %c/%-15.*s ] %.*s\n",
+    int len = fprintf(out, "[ %s.%03ld %8d:%6d:%6d %c/%-15.*s ] %.*s\n",
                       time_buff.data(),
                       nsec / MS_PER_NSEC,
                       entry.uid, entry.pid, entry.tid,
                       kLogChar[entry.priority], static_cast<int>(entry.tagLen),
                       entry.tag, static_cast<int>(message_len), message);
+    fflush(out);
+    // trigger overflow when failed to generate a new fd
+    if (len <= 0) len = kMaxLogSize;
+    return static_cast<size_t>(len);
 }
 
 void Logcat::RefreshFd(bool is_verbose) {
@@ -104,15 +105,19 @@ void Logcat::RefreshFd(bool is_verbose) {
     if (is_verbose) {
         verbose_print_count_ = 0;
         fprintf(verbose_file_.get(), end, verbose_file_part_);
+        fflush(verbose_file_.get());
         verbose_file_ = UniqueFile(env_->CallIntMethod(thiz_, refresh_fd_method_, JNI_TRUE), "a");
         verbose_file_part_++;
         fprintf(verbose_file_.get(), start, verbose_file_part_);
+        fflush(verbose_file_.get());
     } else {
         modules_print_count_ = 0;
         fprintf(modules_file_.get(), end, modules_file_part_);
+        fflush(modules_file_.get());
         modules_file_ = UniqueFile(env_->CallIntMethod(thiz_, refresh_fd_method_, JNI_FALSE), "a");
         modules_file_part_++;
         fprintf(modules_file_.get(), start, modules_file_part_);
+        fflush(modules_file_.get());
     }
 }
 
@@ -199,9 +204,6 @@ void Logcat::Run() {
 
             ProcessBuffer(&msg);
 
-            fflush(verbose_file_.get());
-            fflush(modules_file_.get());
-
             if (verbose_print_count_ >= kMaxLogSize) [[unlikely]] RefreshFd(true);
             if (modules_print_count_ >= kMaxLogSize) [[unlikely]] RefreshFd(false);
         }

core/src/main/cpp/daemon/logcat.h

@@ -5,7 +5,7 @@
 
 #include <android/log.h>
 
-#define NS_PER_SEC 1000000000ULL
+#define NS_PER_SEC 1000000000L
 #define MS_PER_NSEC 1000000
 #define LOGGER_ENTRY_MAX_LEN (5 * 1024)
 

core/src/main/java/org/lsposed/lspd/service/ConfigFileManager.java

@@ -28,6 +28,7 @@ import java.nio.channels.FileChannel;
 import java.nio.channels.FileLock;
 import java.nio.file.FileVisitResult;
 import java.nio.file.Files;
+import java.nio.file.LinkOption;
 import java.nio.file.OpenOption;
 import java.nio.file.Path;
 import java.nio.file.Paths;
@@ -65,12 +66,19 @@ public class ConfigFileManager {
             Files.createDirectories(basePath);
             SELinux.setFileContext(basePath.toString(), "u:object_r:system_file:s0");
             Files.createDirectories(configDirPath);
-            Files.createDirectories(logDirPath);
+            createLogDirPath();
         } catch (IOException e) {
             Log.e(TAG, Log.getStackTraceString(e));
         }
     }
 
+    private static void createLogDirPath() throws IOException {
+        if (!Files.isDirectory(logDirPath, LinkOption.NOFOLLOW_LINKS)) {
+            Files.deleteIfExists(logDirPath);
+        }
+        Files.createDirectories(logDirPath);
+    }
+
     public static Resources getResources() {
         loadRes();
         return res;
@@ -153,12 +161,12 @@ public class ConfigFileManager {
     }
 
     static File getNewVerboseLogPath() throws IOException {
-        Files.createDirectories(logDirPath);
+        createLogDirPath();
         return logDirPath.resolve(getNewLogFileName("verbose")).toFile();
     }
 
     static File getNewModulesLogPath() throws IOException {
-        Files.createDirectories(logDirPath);
+        createLogDirPath();
         return logDirPath.resolve(getNewLogFileName("modules")).toFile();
     }
 

core/src/main/java/org/lsposed/lspd/service/LSPManagerService.java

@@ -591,6 +591,7 @@ public class LSPManagerService extends ILSPManagerService.Stub {
 
     @Override
     public ParcelFileDescriptor getModulesLog() {
+        workerHandler.post(() -> ServiceManager.getLogcatService().checkLogFile());
         return ConfigManager.getInstance().getModulesLog();
     }
 

core/src/main/java/org/lsposed/lspd/service/LogcatService.java

@@ -9,6 +9,10 @@ import org.lsposed.lspd.BuildConfig;
 
 import java.io.File;
 import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.LinkOption;
+import java.nio.file.Path;
+import java.nio.file.Paths;
 
 public class LogcatService implements Runnable {
     private static final String TAG = "LSPosedLogcat";
@@ -16,8 +20,8 @@ public class LogcatService implements Runnable {
             ParcelFileDescriptor.MODE_CREATE |
             ParcelFileDescriptor.MODE_TRUNCATE |
             ParcelFileDescriptor.MODE_APPEND;
-    private File modulesLog = null;
-    private File verboseLog = null;
+    private Path modulesLog = null;
+    private Path verboseLog = null;
     private Thread thread = null;
 
     @SuppressLint("UnsafeDynamicallyLoadedCode")
@@ -43,21 +47,47 @@ public class LogcatService implements Runnable {
     @SuppressWarnings("unused")
     private int refreshFd(boolean isVerboseLog) {
         try {
-            File log = isVerboseLog ? ConfigFileManager.getNewVerboseLogPath() : ConfigFileManager.getNewModulesLogPath();
-            Log.i(TAG, "New " + (isVerboseLog ? "verbose" : "modules") + " log file: " + log);
+            File log;
+            if (isVerboseLog) {
+                checkFdFile(verboseLog);
+                log = ConfigFileManager.getNewVerboseLogPath();
+            } else {
+                checkFdFile(modulesLog);
+                log = ConfigFileManager.getNewModulesLogPath();
+            }
+            Log.i(TAG, "New log file: " + log);
             int fd = ParcelFileDescriptor.open(log, mode).detachFd();
-            var fdFile = new File("/proc/self/fd/" + fd);
+            var fdFile = Paths.get("/proc/self/fd", String.valueOf(fd));
             if (isVerboseLog) verboseLog = fdFile;
             else modulesLog = fdFile;
             return fd;
         } catch (IOException e) {
             if (isVerboseLog) verboseLog = null;
             else modulesLog = null;
-            Log.w(TAG, "someone chattr +i ?", e);
+            Log.w(TAG, "refreshFd", e);
             return -1;
         }
     }
 
+    private static void checkFdFile(Path fdFile) {
+        if (fdFile == null) return;
+        try {
+            var file = Files.readSymbolicLink(fdFile);
+            if (!Files.exists(file)) {
+                var parent = file.getParent();
+                if (!Files.isDirectory(parent, LinkOption.NOFOLLOW_LINKS)) {
+                    Files.deleteIfExists(parent);
+                }
+                Files.createDirectories(parent);
+                var name = file.getFileName().toString();
+                var originName = name.substring(0, name.lastIndexOf(' '));
+                Files.copy(fdFile, parent.resolve(originName));
+            }
+        } catch (IOException e) {
+            Log.w(TAG, "checkFd " + fdFile, e);
+        }
+    }
+
     public boolean isRunning() {
         return thread != null && thread.isAlive();
     }
@@ -91,10 +121,23 @@ public class LogcatService implements Runnable {
     }
 
     public File getVerboseLog() {
-        return verboseLog;
+        return verboseLog.toFile();
     }
 
     public File getModulesLog() {
-        return modulesLog;
+        return modulesLog.toFile();
+    }
+
+    public void checkLogFile() {
+        try {
+            modulesLog.toRealPath();
+        } catch (IOException e) {
+            refresh(false);
+        }
+        try {
+            verboseLog.toRealPath();
+        } catch (IOException e) {
+            refresh(true);
+        }
     }
 }