From a560c0f7cd8f5c02e35e309926530b07442542d8 Mon Sep 17 00:00:00 2001
From: Scott Lahteine <github@thinkyhead.com>
Date: Thu, 15 Mar 2018 22:20:12 -0500
Subject: [PATCH] Add C parameter to M27 to get the current filename

In answer to #10001

Add an option to retrieve the currently open file name (long filename if possible).
---
 Marlin/Marlin_main.cpp | 20 +++++++++++++++-----
 Marlin/cardreader.cpp  | 26 ++++++++++++++++++++++++++
 Marlin/cardreader.h    |  1 +
 3 files changed, 42 insertions(+), 5 deletions(-)

diff --git a/Marlin/Marlin_main.cpp b/Marlin/Marlin_main.cpp
index 5ca60e2db..7080d7583 100644
--- a/Marlin/Marlin_main.cpp
+++ b/Marlin/Marlin_main.cpp
@@ -89,7 +89,9 @@
  * M24  - Start/resume SD print. (Requires SDSUPPORT)
  * M25  - Pause SD print. (Requires SDSUPPORT)
  * M26  - Set SD position in bytes: "M26 S12345". (Requires SDSUPPORT)
- * M27  - Report SD print status. (Requires SDSUPPORT) Or, with 'S<seconds>' set the SD status auto-report interval. (Requires AUTO_REPORT_SD_STATUS)
+ * M27  - Report SD print status. (Requires SDSUPPORT)
+ *        OR, with 'S<seconds>' set the SD status auto-report interval. (Requires AUTO_REPORT_SD_STATUS)
+ *        OR, with 'C' get the current filename.
  * M28  - Start SD write: "M28 /path/file.gco". (Requires SDSUPPORT)
  * M29  - Stop SD write. (Requires SDSUPPORT)
  * M30  - Delete file from SD: "M30 /path/file.gco"
@@ -6882,15 +6884,23 @@ inline void gcode_M17() {
   }
 
   /**
-   * M27: Get SD Card status or set the SD status auto-report interval.
+   * M27: Get SD Card status
+   *      OR, with 'S<seconds>' set the SD status auto-report interval. (Requires AUTO_REPORT_SD_STATUS)
+   *      OR, with 'C' get the current filename.
    */
   inline void gcode_M27() {
+    if (parser.seen('C')) {
+      SERIAL_ECHOPGM("Current file: ");
+      card.printFilename();
+    }
+
     #if ENABLED(AUTO_REPORT_SD_STATUS)
-      if (parser.seenval('S'))
+      else if (parser.seenval('S'))
         card.set_auto_report_interval(parser.value_byte());
-      else
     #endif
-        card.getStatus();
+
+    else
+      card.getStatus();
   }
 
   /**
diff --git a/Marlin/cardreader.cpp b/Marlin/cardreader.cpp
index 3b1fe36f9..8f8b6eba6 100644
--- a/Marlin/cardreader.cpp
+++ b/Marlin/cardreader.cpp
@@ -230,6 +230,28 @@ void CardReader::ls() {
 
 #endif // LONG_FILENAME_HOST_SUPPORT
 
+/**
+ * Echo the DOS 8.3 filename (and long filename, if any)
+ */
+void CardReader::printFilename() {
+  if (file.isOpen()) {
+    char lfilename[FILENAME_LENGTH];
+    file.getFilename(lfilename);
+    SERIAL_ECHO(lfilename);
+    #if ENABLED(LONG_FILENAME_HOST_SUPPORT)
+      getfilename(0, lfilename);
+      if (longFilename[0]) {
+        SERIAL_ECHO(' ');
+        SERIAL_ECHO(longFilename);
+      }
+    #endif
+  }
+  else
+    SERIAL_ECHOPGM("(no file)");
+
+  SERIAL_EOL();
+}
+
 void CardReader::initsd() {
   cardOK = false;
   if (root.isOpen()) root.close();
@@ -428,8 +450,12 @@ void CardReader::openFile(char* name, const bool read, const bool subcall/*=fals
       SERIAL_PROTOCOLPAIR(MSG_SD_FILE_OPENED, fname);
       SERIAL_PROTOCOLLNPAIR(MSG_SD_SIZE, filesize);
       SERIAL_PROTOCOLLNPGM(MSG_SD_FILE_SELECTED);
+
       getfilename(0, fname);
       lcd_setstatus(longFilename[0] ? longFilename : fname);
+      //if (longFilename[0]) {
+      //  SERIAL_PROTOCOLPAIR(MSG_SD_FILE_LONG_NAME, longFilename);
+      //}
     }
     else {
       SERIAL_PROTOCOLPAIR(MSG_SD_OPEN_FILE_FAIL, fname);
diff --git a/Marlin/cardreader.h b/Marlin/cardreader.h
index d0d3ae06f..d9c068e4d 100644
--- a/Marlin/cardreader.h
+++ b/Marlin/cardreader.h
@@ -61,6 +61,7 @@ public:
   );
   void getStatus();
   void printingHasFinished();
+  void printFilename();
 
   #if ENABLED(LONG_FILENAME_HOST_SUPPORT)
     void printLongPath(char *path);