Rotate files while the service is running.

If AppRotateOnline is set, set up a pipe between the application's
stdout/stderr and a new thread which reads all input and writes to the
configured output file(s).

If a file breaches the configured AppRotateBytes threshold while the
service is running, close and rotate the file then resume logging to
a new file.

This behaviour is not the default due to the potential for things to go
wrong.  We have to juggle file handles and might hit a read or write
error which causes logging to fail thus losing all output until the
service is restarted, etc etc.

Thanks Doug Watson.

README.txt

@@ -314,6 +314,15 @@ Rotation is independent of the CreateFile() parameters used to open the files.
 They will be rotated regardless of whether NSSM would otherwise have appended
 or replaced them.
 
+NSSM can also rotate files which hit the configured size threshold while the
+service is running.  To enable this feature, set AppRotateOnline to a non-zero
+value.
+
+Note that online rotation requires NSSM to intercept the application's I/O
+and create the output files on its behalf.  This is more complex and
+error-prone than simply redirecting the I/O streams before launching the
+application.  Therefore online rotation is not enabled by default.
+
 
 Environment variables
 ---------------------

gui.cpp

@@ -152,9 +152,11 @@ int nssm_gui(int resource, nssm_service_t *service) {
     if (service->stdout_disposition == CREATE_ALWAYS) SendDlgItemMessage(tablist[NSSM_TAB_ROTATION], IDC_TRUNCATE, BM_SETCHECK, BST_CHECKED, 0);
     if (service->rotate_files) {
       SendDlgItemMessage(tablist[NSSM_TAB_ROTATION], IDC_ROTATE, BM_SETCHECK, BST_CHECKED, 0);
+      EnableWindow(GetDlgItem(tablist[NSSM_TAB_ROTATION], IDC_ROTATE_ONLINE), 1);
       EnableWindow(GetDlgItem(tablist[NSSM_TAB_ROTATION], IDC_ROTATE_SECONDS), 1);
       EnableWindow(GetDlgItem(tablist[NSSM_TAB_ROTATION], IDC_ROTATE_BYTES_LOW), 1);
     }
+    if (service->rotate_stdout_online || service->rotate_stderr_online) SendDlgItemMessage(tablist[NSSM_TAB_ROTATION], IDC_ROTATE_ONLINE, BM_SETCHECK, BST_CHECKED, 0);
     SetDlgItemInt(tablist[NSSM_TAB_ROTATION], IDC_ROTATE_SECONDS, service->rotate_seconds, 0);
     if (! service->rotate_bytes_high) SetDlgItemInt(tablist[NSSM_TAB_ROTATION], IDC_ROTATE_BYTES_LOW, service->rotate_bytes_low, 0);
 
@@ -252,6 +254,7 @@ static inline void set_affinity_enabled(unsigned char enabled) {
 }
 
 static inline void set_rotation_enabled(unsigned char enabled) {
+  EnableWindow(GetDlgItem(tablist[NSSM_TAB_ROTATION], IDC_ROTATE_ONLINE), enabled);
   EnableWindow(GetDlgItem(tablist[NSSM_TAB_ROTATION], IDC_ROTATE_SECONDS), enabled);
   EnableWindow(GetDlgItem(tablist[NSSM_TAB_ROTATION], IDC_ROTATE_BYTES_LOW), enabled);
 }
@@ -505,6 +508,7 @@ int configure(HWND window, nssm_service_t *service, nssm_service_t *orig_service
   /* Get rotation stuff. */
   if (SendDlgItemMessage(tablist[NSSM_TAB_ROTATION], IDC_ROTATE, BM_GETCHECK, 0, 0) & BST_CHECKED) {
     service->rotate_files = true;
+    if (SendDlgItemMessage(tablist[NSSM_TAB_ROTATION], IDC_ROTATE_ONLINE, BM_GETCHECK, 0, 0) & BST_CHECKED) service->rotate_stdout_online = service->rotate_stderr_online = true;
     check_number(tablist[NSSM_TAB_ROTATION], IDC_ROTATE_SECONDS, &service->rotate_seconds);
     check_number(tablist[NSSM_TAB_ROTATION], IDC_ROTATE_BYTES_LOW, &service->rotate_bytes_low);
   }
@@ -1027,6 +1031,7 @@ INT_PTR CALLBACK nssm_dlg(HWND window, UINT message, WPARAM w, LPARAM l) {
       ShowWindow(tablist[NSSM_TAB_ROTATION], SW_HIDE);
 
       /* Set defaults. */
+      SendDlgItemMessage(tablist[NSSM_TAB_ROTATION], IDC_ROTATE_ONLINE, BM_SETCHECK, BST_UNCHECKED, 0);
       SetDlgItemInt(tablist[NSSM_TAB_ROTATION], IDC_ROTATE_SECONDS, 0, 0);
       SetDlgItemInt(tablist[NSSM_TAB_ROTATION], IDC_ROTATE_BYTES_LOW, 0, 0);
       set_rotation_enabled(0);

io.cpp

@@ -1,5 +1,19 @@
 #include "nssm.h"
 
+static HANDLE create_logging_thread(logger_t *logger) {
+  HANDLE thread_handle = CreateThread(NULL, 0, log_and_rotate, (void *) logger, 0, logger->tid_ptr);
+  if (! thread_handle) log_event(EVENTLOG_ERROR_TYPE, NSSM_EVENT_CREATETHREAD_FAILED, error_string(GetLastError()), 0);
+  return thread_handle;
+}
+
+static inline void write_bom(logger_t *logger) {
+  wchar_t bom = L'\ufeff';
+  unsigned long out;
+  if (! WriteFile(logger->write_handle, (void *) &bom, sizeof(bom), &out, 0)) {
+    log_event(EVENTLOG_WARNING_TYPE, NSSM_EVENT_SOMEBODY_SET_UP_US_THE_BOM, logger->service_name, logger->path, error_string(GetLastError()), 0);
+  }
+}
+
 /* Get path, share mode, creation disposition and flags for a stream. */
 int get_createfile_parameters(HKEY key, TCHAR *prefix, TCHAR *path, unsigned long *sharing, unsigned long default_sharing, unsigned long *disposition, unsigned long default_disposition, unsigned long *flags, unsigned long default_flags) {
   TCHAR value[NSSM_STDIO_LENGTH];
@@ -93,6 +107,22 @@ HANDLE append_to_file(TCHAR *path, unsigned long sharing, SECURITY_ATTRIBUTES *a
   return CreateFile(path, FILE_WRITE_DATA, sharing, attributes, disposition, flags, 0);
 }
 
+static void rotated_filename(TCHAR *path, TCHAR *rotated, unsigned long rotated_len, SYSTEMTIME *st) {
+  if (! st) {
+    SYSTEMTIME now;
+    st = &now;
+    GetSystemTime(st);
+  }
+
+  TCHAR buffer[MAX_PATH];
+  memmove(buffer, path, sizeof(buffer));
+  TCHAR *ext = PathFindExtension(buffer);
+  TCHAR extension[MAX_PATH];
+  _sntprintf_s(extension, _countof(extension), _TRUNCATE, _T("-%04u%02u%02uT%02u%02u%02u.%03u%s"), st->wYear, st->wMonth, st->wDay, st->wHour, st->wMinute, st->wSecond, st->wMilliseconds, ext);
+  *ext = _T('\0');
+  _sntprintf_s(rotated, rotated_len, _TRUNCATE, _T("%s%s"), buffer, extension);
+}
+
 void rotate_file(TCHAR *service_name, TCHAR *path, unsigned long seconds, unsigned long low, unsigned long high) {
   unsigned long error;
 
@@ -146,14 +176,8 @@ void rotate_file(TCHAR *service_name, TCHAR *path, unsigned long seconds, unsign
   /* Get new filename. */
   FileTimeToSystemTime(&info.ftLastWriteTime, &st);
 
-  TCHAR buffer[MAX_PATH];
-  memmove(buffer, path, sizeof(buffer));
-  TCHAR *ext = PathFindExtension(buffer);
-  TCHAR extension[MAX_PATH];
-  _sntprintf_s(extension, _countof(extension), _TRUNCATE, _T("-%04u%02u%02uT%02u%02u%02u.%03u%s"), st.wYear, st.wMonth, st.wDay, st.wHour, st.wMinute, st.wSecond, st.wMilliseconds, ext);
-  *ext = _T('\0');
   TCHAR rotated[MAX_PATH];
-  _sntprintf_s(rotated, _countof(rotated), _TRUNCATE, _T("%s%s"), buffer, extension);
+  rotated_filename(path, rotated, _countof(rotated), &st);
 
   /* Rotate. */
   if (MoveFile(path, rotated)) return;
@@ -186,6 +210,10 @@ int get_output_handles(nssm_service_t *service, HKEY key, STARTUPINFO *si) {
     set_flags = true;
   }
 
+  ULARGE_INTEGER size;
+  size.LowPart = service->rotate_bytes_low;
+  size.HighPart = service->rotate_bytes_high;
+
   /* stdout */
   if (get_createfile_parameters(key, NSSM_REG_STDOUT, service->stdout_path, &service->stdout_sharing, NSSM_STDOUT_SHARING, &service->stdout_disposition, NSSM_STDOUT_DISPOSITION, &service->stdout_flags, NSSM_STDOUT_FLAGS)) {
     service->stdout_sharing = service->stdout_disposition = service->stdout_flags = 0;
@@ -194,8 +222,58 @@ int get_output_handles(nssm_service_t *service, HKEY key, STARTUPINFO *si) {
   }
   if (si && service->stdout_path[0]) {
     if (service->rotate_files) rotate_file(service->name, service->stdout_path, service->rotate_seconds, service->rotate_bytes_low, service->rotate_bytes_high);
-    si->hStdOutput = append_to_file(service->stdout_path, service->stdout_sharing, &attributes, service->stdout_disposition, service->stdout_flags);
-    if (! si->hStdOutput) return 4;
+    HANDLE stdout_handle = append_to_file(service->stdout_path, service->stdout_sharing, 0, service->stdout_disposition, service->stdout_flags);
+    if (! stdout_handle) {
+      log_event(EVENTLOG_ERROR_TYPE, NSSM_EVENT_CREATEFILE_FAILED, service->stdout_path, error_string(GetLastError()), 0);
+      return 4;
+    }
+
+    /* Try online rotation only if a size threshold is set. */
+    logger_t *stdout_logger = 0;
+    if (service->rotate_files && service->rotate_stdout_online && size.QuadPart) {
+      stdout_logger = (logger_t *) HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(logger_t));
+      if (stdout_logger) {
+        /* Pipe between application's stdout and our logging handle. */
+        if (CreatePipe(&service->stdout_pipe, &si->hStdOutput, &attributes, 0)) {
+          stdout_logger->service_name = service->name;
+          stdout_logger->path = service->stdout_path;
+          stdout_logger->sharing = service->stdout_sharing;
+          stdout_logger->disposition = service->stdout_disposition;
+          stdout_logger->flags = service->stdout_flags;
+          stdout_logger->read_handle = service->stdout_pipe;
+          stdout_logger->write_handle = stdout_handle;
+          stdout_logger->size = (__int64) size.QuadPart;
+          stdout_logger->tid_ptr = &service->stdout_tid;
+
+          /* Logging thread. */
+          service->stdout_thread = create_logging_thread(stdout_logger);
+          if (! service->stdout_thread) {
+            log_event(EVENTLOG_ERROR_TYPE, NSSM_EVENT_CREATEPIPE_FAILED, service->name, service->stdout_path, error_string(GetLastError()));
+            CloseHandle(service->stdout_pipe);
+            CloseHandle(si->hStdOutput);
+            service->stdout_tid = 0;
+          }
+        }
+        else service->stdout_tid = 0;
+      }
+      else {
+        log_event(EVENTLOG_ERROR_TYPE, NSSM_EVENT_OUT_OF_MEMORY, _T("stdout_logger"), _T("get_output_handles()"), 0);
+        service->stdout_tid = 0;
+      }
+
+      /* Fall through to try direct I/O. */
+      if (! service->stdout_tid) log_event(EVENTLOG_ERROR_TYPE, NSSM_EVENT_CREATEPIPE_FAILED, service->name, service->stdout_path, error_string(GetLastError()));
+    }
+
+    if (! service->stdout_tid) {
+      if (stdout_logger) HeapFree(GetProcessHeap(), 0, stdout_logger);
+      if (! DuplicateHandle(GetCurrentProcess(), stdout_handle, GetCurrentProcess(), &si->hStdOutput, 0, true, DUPLICATE_CLOSE_SOURCE | DUPLICATE_SAME_ACCESS)) {
+        log_event(EVENTLOG_ERROR_TYPE, NSSM_EVENT_DUPLICATEHANDLE_FAILED, NSSM_REG_STDOUT, error_string(GetLastError()), 0);
+        return 4;
+      }
+      service->rotate_stdout_online = false;
+    }
+
     set_flags = true;
   }
 
@@ -211,6 +289,7 @@ int get_output_handles(nssm_service_t *service, HKEY key, STARTUPINFO *si) {
       service->stderr_sharing = service->stdout_sharing;
       service->stderr_disposition = service->stdout_disposition;
       service->stderr_flags = service->stdout_flags;
+      service->rotate_stderr_online = false;
 
       if (si) {
         /* Two handles to the same file will create a race. */
@@ -222,13 +301,59 @@ int get_output_handles(nssm_service_t *service, HKEY key, STARTUPINFO *si) {
     }
     else if (si) {
       if (service->rotate_files) rotate_file(service->name, service->stderr_path, service->rotate_seconds, service->rotate_bytes_low, service->rotate_bytes_high);
-      si->hStdError = append_to_file(service->stderr_path, service->stdout_sharing, &attributes, service->stdout_disposition, service->stdout_flags);
-      if (! si->hStdError) {
+      HANDLE stderr_handle = append_to_file(service->stderr_path, service->stdout_sharing, 0, service->stdout_disposition, service->stdout_flags);
+      if (! stderr_handle) {
         log_event(EVENTLOG_ERROR_TYPE, NSSM_EVENT_CREATEFILE_FAILED, service->stderr_path, error_string(GetLastError()), 0);
         return 7;
       }
-      SetEndOfFile(si->hStdError);
+
+      /* Try online rotation only if a size threshold is set. */
+      logger_t *stderr_logger = 0;
+      if (service->rotate_files && service->rotate_stderr_online && size.QuadPart) {
+        stderr_logger = (logger_t *) HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, sizeof(logger_t));
+        if (stderr_logger) {
+          /* Pipe between application's stderr and our logging handle. */
+          if (CreatePipe(&service->stderr_pipe, &si->hStdError, &attributes, 0)) {
+            stderr_logger->service_name = service->name;
+            stderr_logger->path = service->stderr_path;
+            stderr_logger->sharing = service->stderr_sharing;
+            stderr_logger->disposition = service->stderr_disposition;
+            stderr_logger->flags = service->stderr_flags;
+            stderr_logger->read_handle = service->stderr_pipe;
+            stderr_logger->write_handle = stderr_handle;
+            stderr_logger->size = (__int64) size.QuadPart;
+            stderr_logger->tid_ptr = &service->stderr_tid;
+
+            /* Logging thread. */
+            service->stderr_thread = create_logging_thread(stderr_logger);
+            if (! service->stderr_thread) {
+              log_event(EVENTLOG_ERROR_TYPE, NSSM_EVENT_CREATEPIPE_FAILED, service->name, service->stderr_path, error_string(GetLastError()));
+              CloseHandle(service->stderr_pipe);
+              CloseHandle(si->hStdError);
+              service->stderr_tid = 0;
+            }
+          }
+          else service->stderr_tid = 0;
+        }
+        else {
+          log_event(EVENTLOG_ERROR_TYPE, NSSM_EVENT_OUT_OF_MEMORY, _T("stderr_logger"), _T("get_output_handles()"), 0);
+          service->stderr_tid = 0;
+        }
+
+        /* Fall through to try direct I/O. */
+        if (! service->stderr_tid) log_event(EVENTLOG_ERROR_TYPE, NSSM_EVENT_CREATEPIPE_FAILED, service->name, service->stderr_path, error_string(GetLastError()));
+      }
+
+      if (! service->stderr_tid) {
+        if (stderr_logger) HeapFree(GetProcessHeap(), 0, stderr_logger);
+        if (! DuplicateHandle(GetCurrentProcess(), stderr_handle, GetCurrentProcess(), &si->hStdError, 0, true, DUPLICATE_CLOSE_SOURCE | DUPLICATE_SAME_ACCESS)) {
+          log_event(EVENTLOG_ERROR_TYPE, NSSM_EVENT_DUPLICATEHANDLE_FAILED, NSSM_REG_STDERR, error_string(GetLastError()), 0);
+          return 7;
+        }
+        service->rotate_stderr_online = false;
+      }
     }
+
     set_flags = true;
   }
 
@@ -243,8 +368,111 @@ int get_output_handles(nssm_service_t *service, HKEY key, STARTUPINFO *si) {
   return 0;
 }
 
-void close_output_handles(STARTUPINFO *si) {
+void close_output_handles(STARTUPINFO *si, bool close_stdout, bool close_stderr) {
   if (si->hStdInput) CloseHandle(si->hStdInput);
-  if (si->hStdOutput) CloseHandle(si->hStdOutput);
-  if (si->hStdError) CloseHandle(si->hStdError);
+  if (si->hStdOutput && close_stdout) CloseHandle(si->hStdOutput);
+  if (si->hStdError && close_stderr) CloseHandle(si->hStdError);
+}
+
+void close_output_handles(STARTUPINFO *si) {
+  return close_output_handles(si, true, true);
+}
+
+/* Wrapper to be called in a new thread for logging. */
+unsigned long WINAPI log_and_rotate(void *arg) {
+  logger_t *logger = (logger_t *) arg;
+  if (! logger) return 1;
+
+  __int64 size;
+  BY_HANDLE_FILE_INFORMATION info;
+
+  /* Find initial file size. */
+  if (! GetFileInformationByHandle(logger->write_handle, &info)) logger->size = 0LL;
+  else {
+    ULARGE_INTEGER l;
+    l.HighPart = info.nFileSizeHigh;
+    l.LowPart = info.nFileSizeLow;
+    size = l.QuadPart;
+  }
+
+  char buffer[80];
+  void *address;
+  unsigned long in, out;
+  while (true) {
+    /* Read data from the pipe. */
+    address = &buffer;
+    if (! ReadFile(logger->read_handle, address, sizeof(buffer), &in, 0)) {
+      log_event(EVENTLOG_ERROR_TYPE, NSSM_EVENT_READFILE_FAILED, logger->service_name, logger->path, error_string(GetLastError()), 0);
+      return 2;
+    }
+
+    if (size + (__int64) in >= logger->size) {
+      /* Look for newline. */
+      unsigned long i;
+      for (i = 0; i < in; i++) {
+        if (buffer[i] == '\n') {
+          unsigned char unicode = IsTextUnicode(address, sizeof(buffer), 0);
+          if (unicode) i += sizeof(wchar_t);
+          else i += sizeof(char);
+
+          /* Write up to the newline. */
+          if (! WriteFile(logger->write_handle, address, i, &out, 0)) {
+            log_event(EVENTLOG_ERROR_TYPE, NSSM_EVENT_WRITEFILE_FAILED, logger->service_name, logger->path, error_string(GetLastError()), 0);
+            return 3;
+          }
+
+          /* Rotate. */
+          TCHAR rotated[MAX_PATH];
+          rotated_filename(logger->path, rotated, _countof(rotated), 0);
+
+          /*
+            Ideally we'd try the rename first then close the handle but
+            MoveFile() will fail if the handle is still open so we must
+            risk losing everything.
+          */
+          CloseHandle(logger->write_handle);
+          if (! MoveFile(logger->path, rotated)) {
+            unsigned long error = GetLastError();
+            if (error != ERROR_FILE_NOT_FOUND) {
+              log_event(EVENTLOG_ERROR_TYPE, NSSM_EVENT_ROTATE_FILE_FAILED, logger->service_name, logger->path, _T("MoveFile()"), rotated, error_string(error), 0);
+              /* We can at least try to re-open the existing file. */
+              logger->disposition = OPEN_ALWAYS;
+            }
+          }
+
+          /* Reopen. */
+          logger->write_handle = append_to_file(logger->path, logger->sharing, 0, logger->disposition, logger->flags);
+          if (! logger->write_handle) {
+            log_event(EVENTLOG_ERROR_TYPE, NSSM_EVENT_CREATEFILE_FAILED, logger->path, error_string(GetLastError()), 0);
+            /* Oh dear.  Now we can't log anything further. */
+            return 4;
+          }
+
+          /* Unicode files need a new BOM. */
+          if (unicode) write_bom(logger);
+
+          /* Resume writing after the newline. */
+          size = 0LL;
+          address = (void *) ((char *) address + i);
+          in -= i;
+
+          break;
+        }
+      }
+    }
+    else if (! size) {
+      /* Write a BOM to the new file. */
+      if (IsTextUnicode(address, sizeof(buffer), 0)) write_bom(logger);
+    }
+
+    /* Write the data. */
+    if (! WriteFile(logger->write_handle, address, in, &out, 0)) {
+      log_event(EVENTLOG_ERROR_TYPE, NSSM_EVENT_WRITEFILE_FAILED, logger->service_name, logger->path, error_string(GetLastError()), 0);
+      return 3;
+    }
+
+    size += (__int64) out;
+  }
+
+  return 0;
 }

io.h

@@ -11,12 +11,26 @@
 #define NSSM_STDERR_DISPOSITION OPEN_ALWAYS
 #define NSSM_STDERR_FLAGS FILE_ATTRIBUTE_NORMAL
 
+typedef struct {
+  TCHAR *service_name;
+  TCHAR *path;
+  unsigned long sharing;
+  unsigned long disposition;
+  unsigned long flags;
+  HANDLE read_handle;
+  HANDLE write_handle;
+  __int64 size;
+  unsigned long *tid_ptr;
+} logger_t;
+
 int get_createfile_parameters(HKEY, TCHAR *, TCHAR *, unsigned long *, unsigned long, unsigned long *, unsigned long, unsigned long *, unsigned long);
 int set_createfile_parameter(HKEY, TCHAR *, TCHAR *, unsigned long);
 int delete_createfile_parameter(HKEY, TCHAR *, TCHAR *);
 HANDLE append_to_file(TCHAR *, unsigned long, SECURITY_ATTRIBUTES *, unsigned long, unsigned long);
 void rotate_file(TCHAR *, TCHAR *, unsigned long, unsigned long, unsigned long);
 int get_output_handles(nssm_service_t *, HKEY, STARTUPINFO *);
+void close_output_handles(STARTUPINFO *, bool, bool);
 void close_output_handles(STARTUPINFO *);
+unsigned long WINAPI log_and_rotate(void *);
 
 #endif

registry.cpp

@@ -111,6 +111,8 @@ int create_parameters(nssm_service_t *service, bool editing) {
   }
   if (service->rotate_files) set_number(key, NSSM_REG_ROTATE, 1);
   else if (editing) RegDeleteValue(key, NSSM_REG_ROTATE);
+  if (service->rotate_stdout_online) set_number(key, NSSM_REG_ROTATE_ONLINE, 1);
+  else if (editing) RegDeleteValue(key, NSSM_REG_ROTATE_ONLINE);
   if (service->rotate_seconds) set_number(key, NSSM_REG_ROTATE_SECONDS, service->rotate_seconds);
   else if (editing) RegDeleteValue(key, NSSM_REG_ROTATE_SECONDS);
   if (service->rotate_bytes_low) set_number(key, NSSM_REG_ROTATE_BYTES_LOW, service->rotate_bytes_low);
@@ -573,6 +575,11 @@ int get_parameters(nssm_service_t *service, STARTUPINFO *si) {
     else service->rotate_files = false;
   }
   else service->rotate_files = false;
+  if (get_number(key, NSSM_REG_ROTATE_ONLINE, &rotate_files, false) == 1) {
+    if (rotate_files) service->rotate_stdout_online = service->rotate_stderr_online = true;
+    else service->rotate_stdout_online = service->rotate_stderr_online = false;
+  }
+  else service->rotate_stdout_online = service->rotate_stderr_online = false;
   if (get_number(key, NSSM_REG_ROTATE_SECONDS, &service->rotate_seconds, false) != 1) service->rotate_seconds = 0;
   if (get_number(key, NSSM_REG_ROTATE_BYTES_LOW, &service->rotate_bytes_low, false) != 1) service->rotate_bytes_low = 0;
   if (get_number(key, NSSM_REG_ROTATE_BYTES_HIGH, &service->rotate_bytes_high, false) != 1) service->rotate_bytes_high = 0;

registry.h

@@ -21,6 +21,7 @@
 #define NSSM_REG_STDIO_DISPOSITION _T("CreationDisposition")
 #define NSSM_REG_STDIO_FLAGS _T("FlagsAndAttributes")
 #define NSSM_REG_ROTATE _T("AppRotateFiles")
+#define NSSM_REG_ROTATE_ONLINE _T("AppRotateOnline")
 #define NSSM_REG_ROTATE_SECONDS _T("AppRotateSeconds")
 #define NSSM_REG_ROTATE_BYTES_LOW _T("AppRotateBytes")
 #define NSSM_REG_ROTATE_BYTES_HIGH _T("AppRotateBytesHigh")

resource.h

@@ -46,20 +46,21 @@
 #define IDC_ENVIRONMENT_REPLACE         1027
 #define IDC_TRUNCATE                    1028
 #define IDC_ROTATE                      1029
-#define IDC_ROTATE_SECONDS              1030
-#define IDC_ROTATE_BYTES_LOW            1031
-#define IDC_DISPLAYNAME                 1032
-#define IDC_DESCRIPTION                 1033
-#define IDC_STARTUP                     1034
-#define IDC_LOCALSYSTEM                 1035
-#define IDC_INTERACT                    1036
-#define IDC_ACCOUNT                     1037
-#define IDC_USERNAME                    1038
-#define IDC_PASSWORD1                   1039
-#define IDC_PASSWORD2                   1040
-#define IDC_PRIORITY                    1041
-#define IDC_AFFINITY_ALL                1042
-#define IDC_AFFINITY                    1043
+#define IDC_ROTATE_ONLINE               1030
+#define IDC_ROTATE_SECONDS              1031
+#define IDC_ROTATE_BYTES_LOW            1032
+#define IDC_DISPLAYNAME                 1033
+#define IDC_DESCRIPTION                 1034
+#define IDC_STARTUP                     1035
+#define IDC_LOCALSYSTEM                 1036
+#define IDC_INTERACT                    1037
+#define IDC_ACCOUNT                     1038
+#define IDC_USERNAME                    1039
+#define IDC_PASSWORD1                   1040
+#define IDC_PASSWORD2                   1041
+#define IDC_PRIORITY                    1042
+#define IDC_AFFINITY_ALL                1043
+#define IDC_AFFINITY                    1044
 
 // Next default values for new objects
 // 
@@ -67,7 +68,7 @@
 #ifndef APSTUDIO_READONLY_SYMBOLS
 #define _APS_NEXT_RESOURCE_VALUE        115
 #define _APS_NEXT_COMMAND_VALUE         40001
-#define _APS_NEXT_CONTROL_VALUE         1044
+#define _APS_NEXT_CONTROL_VALUE         1045
 #define _APS_NEXT_SYMED_VALUE           101
 #endif
 #endif

service.cpp

@@ -1431,7 +1431,7 @@ int start_service(nssm_service_t *service) {
 
   if (get_process_creation_time(service->process_handle, &service->creation_time)) ZeroMemory(&service->creation_time, sizeof(service->creation_time));
 
-  close_output_handles(&si);
+  close_output_handles(&si, ! service->rotate_stdout_online, ! service->rotate_stderr_online);
 
   if (service->affinity) {
     /*

service.h

@@ -57,11 +57,19 @@ typedef struct {
   unsigned long stdout_sharing;
   unsigned long stdout_disposition;
   unsigned long stdout_flags;
+  HANDLE stdout_pipe;
+  HANDLE stdout_thread;
+  unsigned long stdout_tid;
   TCHAR stderr_path[MAX_PATH];
   unsigned long stderr_sharing;
   unsigned long stderr_disposition;
   unsigned long stderr_flags;
+  HANDLE stderr_pipe;
+  HANDLE stderr_thread;
+  unsigned long stderr_tid;
   bool rotate_files;
+  bool rotate_stdout_online;
+  bool rotate_stderr_online;
   unsigned long rotate_seconds;
   unsigned long rotate_bytes_low;
   unsigned long rotate_bytes_high;

settings.cpp

@@ -830,6 +830,7 @@ settings_t settings[] = {
   { NSSM_REG_KILL_THREADS_GRACE_PERIOD, REG_DWORD, (void *) NSSM_KILL_THREADS_GRACE_PERIOD, false, 0, setting_set_number, setting_get_number },
   { NSSM_REG_THROTTLE, REG_DWORD, (void *) NSSM_RESET_THROTTLE_RESTART, false, 0, setting_set_number, setting_get_number },
   { NSSM_REG_ROTATE, REG_DWORD, 0, false, 0, setting_set_number, setting_get_number },
+  { NSSM_REG_ROTATE_ONLINE, REG_DWORD, 0, false, 0, setting_set_number, setting_get_number },
   { NSSM_REG_ROTATE_SECONDS, REG_DWORD, 0, false, 0, setting_set_number, setting_get_number },
   { NSSM_REG_ROTATE_BYTES_LOW, REG_DWORD, 0, false, 0, setting_set_number, setting_get_number },
   { NSSM_REG_ROTATE_BYTES_HIGH, REG_DWORD, 0, false, 0, setting_set_number, setting_get_number },