From 975c626dc392b298b68924278b42414ddb56fa31 Mon Sep 17 00:00:00 2001
From: zdenop <zdenop@gmail.com>
Date: Mon, 11 Nov 2019 08:58:03 +0100
Subject: [PATCH] Fail if no valid lstmf file was written (fix issue #2741)

Signed-off-by: Stefan Weil <sw@weilnetz.de>

# Conflicts:
#	src/ccmain/linerec.cpp
---
 src/api/baseapi.cpp         |  4 +++-
 src/ccmain/linerec.cpp      | 21 ++++++++++++---------
 src/ccmain/tesseractclass.h |  3 ++-
 3 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/src/api/baseapi.cpp b/src/api/baseapi.cpp
index 90c6a1c91..9f79dd327 100644
--- a/src/api/baseapi.cpp
+++ b/src/api/baseapi.cpp
@@ -858,7 +858,9 @@ int TessBaseAPI::Recognize(ETEXT_DESC* monitor) {
   }
 
   if (tesseract_->tessedit_train_line_recognizer) {
-    tesseract_->TrainLineRecognizer(*input_file_, *output_file_, block_list_);
+    if (!tesseract_->TrainLineRecognizer(*input_file_, *output_file_, block_list_)) {
+      return -1;
+    }
     tesseract_->CorrectClassifyWords(page_res_);
     return 0;
   }
diff --git a/src/ccmain/linerec.cpp b/src/ccmain/linerec.cpp
index 6f1c77714..fa6217c9b 100644
--- a/src/ccmain/linerec.cpp
+++ b/src/ccmain/linerec.cpp
@@ -40,16 +40,17 @@ const float kWorstDictCertainty = -25.0f;
 // Generates training data for training a line recognizer, eg LSTM.
 // Breaks the page into lines, according to the boxes, and writes them to a
 // serialized DocumentData based on output_basename.
-void Tesseract::TrainLineRecognizer(const STRING& input_imagename,
+// Return true if successful, false if an error occurred.
+bool Tesseract::TrainLineRecognizer(const STRING& input_imagename,
                                     const STRING& output_basename,
                                     BLOCK_LIST *block_list) {
   STRING lstmf_name = output_basename + ".lstmf";
   DocumentData images(lstmf_name);
   if (applybox_page > 0) {
     // Load existing document for the previous pages.
-    if (!images.LoadDocument(lstmf_name.string(), 0, 0, nullptr)) {
-      tprintf("Failed to read training data from %s!\n", lstmf_name.string());
-      return;
+    if (!images.LoadDocument(lstmf_name.c_str(), 0, 0, nullptr)) {
+      tprintf("Failed to read training data from %s!\n", lstmf_name.c_str());
+      return false;
     }
   }
   GenericVector<TBOX> boxes;
@@ -58,18 +59,20 @@ void Tesseract::TrainLineRecognizer(const STRING& input_imagename,
   if (!ReadAllBoxes(applybox_page, false, input_imagename, &boxes, &texts, nullptr,
                     nullptr) ||
       boxes.empty()) {
-    tprintf("Failed to read boxes from %s\n", input_imagename.string());
-    return;
+    tprintf("Failed to read boxes from %s\n", input_imagename.c_str());
+    return false;
   }
   TrainFromBoxes(boxes, texts, block_list, &images);
   if (images.NumPages() <= 0) {
     tprintf("Failed to read pages from %s\n", input_imagename.c_str());
-    return;
+    return false;
   }
   images.Shuffle();
-  if (!images.SaveDocument(lstmf_name.string(), nullptr)) {
-    tprintf("Failed to write training data to %s!\n", lstmf_name.string());
+  if (!images.SaveDocument(lstmf_name.c_str(), nullptr)) {
+    tprintf("Failed to write training data to %s!\n", lstmf_name.c_str());
+    return false;
   }
+  return true;
 }
 
 // Generates training data for training a line recognizer, eg LSTM.
diff --git a/src/ccmain/tesseractclass.h b/src/ccmain/tesseractclass.h
index a9fc5d094..b2abcf4c1 100644
--- a/src/ccmain/tesseractclass.h
+++ b/src/ccmain/tesseractclass.h
@@ -336,7 +336,8 @@ class Tesseract : public Wordrec {
   // Generates training data for training a line recognizer, eg LSTM.
   // Breaks the page into lines, according to the boxes, and writes them to a
   // serialized DocumentData based on output_basename.
-  void TrainLineRecognizer(const STRING& input_imagename,
+  // Return true if successful, false if an error occurred.
+  bool TrainLineRecognizer(const STRING& input_imagename,
                            const STRING& output_basename,
                            BLOCK_LIST* block_list);
   // Generates training data for training a line recognizer, eg LSTM.