add: debug xml-parsing errors

When a file cannot be loaded because of a mis-formatted XML-tag,
a message is sent to stderr, where to find the error in the file.
Additionally that part of the XML-file will be written to stderr.

inc/helpers.cpp

@@ -28,6 +28,7 @@
 #include <random>       // for random values of uuid
 #include <cmath>        // for sqrt, atan2, isnan(), ...
 #include <iomanip>      // for IO-Operations
+#include <fstream>      // for file-reading
 #include <sstream>      // for String-Streams
 #include <regex>        // for "double"-Check
 
@@ -247,3 +248,91 @@ void CheckForDoubleString(std::string& sArg){
 // ###   END: does the string contain a double- or int-value   ###
 // ###############################################################
 //
+
+
+
+
+//
+// ###############################################################
+// ###            determine the terminal-geometry              ###
+// ###############################################################
+//
+void get_terminal_size(size_t& width, size_t& height) {
+// Quelle:
+// https://stackoverflow.com/questions/23369503/get-size-of-terminal-window-rows-columns
+#if defined(_WIN32)
+    CONSOLE_SCREEN_BUFFER_INFO csbi;
+    GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE), &csbi);
+    width = (size_t)(csbi.srWindow.Right-csbi.srWindow.Left+1);
+    height = (size_t)(csbi.srWindow.Bottom-csbi.srWindow.Top+1);
+#elif defined(__linux__) || defined(__APPLE__)
+    struct winsize w;
+    ioctl(fileno(stdout), TIOCGWINSZ, &w);
+    width = (size_t)(w.ws_col);
+    height = (size_t)(w.ws_row);
+#endif // Windows/Linux
+}
+// ---
+size_t get_terminal_height(void) {
+// abgeleitet von: get_terminal_size
+#if defined(_WIN32)
+    CONSOLE_SCREEN_BUFFER_INFO csbi;
+    GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE), &csbi);
+    return (size_t)(csbi.srWindow.Bottom-csbi.srWindow.Top+1);
+#elif defined(__linux__) || defined(__APPLE__)
+    struct winsize w;
+    ioctl(fileno(stdout), TIOCGWINSZ, &w);
+    return (size_t)(w.ws_row);
+#endif // Windows/Linux
+}
+// ---
+size_t get_terminal_width(void) {
+// abgeleitet von: get_terminal_size
+#if defined(_WIN32)
+    CONSOLE_SCREEN_BUFFER_INFO csbi;
+    GetConsoleScreenBufferInfo(GetStdHandle(STD_OUTPUT_HANDLE), &csbi);
+    return (size_t)(csbi.srWindow.Right-csbi.srWindow.Left+1);
+#elif defined(__linux__) || defined(__APPLE__)
+    struct winsize w;
+    ioctl(fileno(stdout), TIOCGWINSZ, &w);
+    return (size_t)(w.ws_col);
+#endif // Windows/Linux
+}
+//
+// ###############################################################
+// ###          END: determine the terminal-geometry           ###
+// ###############################################################
+//
+
+
+
+//
+// ###############################################################
+// ###             read a piece from a text-file               ###
+// ###############################################################
+//
+// returns a string of "length" characters around "position"
+// the existence of "file" MUST be checked before!!!
+std::string ReadPieceOfFile(const std::string file, size_t pos, const size_t length) {
+    std::ifstream strm;
+    strm.open ( file );
+    strm.seekg (0, strm.end);
+    if (pos < (length/2)) {
+        pos = 0;
+    } else if (pos > ((size_t)strm.tellg() - (length/2) )) {
+        pos = (size_t)strm.tellg() - length;
+    } else {
+        pos -= (length/2);
+    }
+    strm.seekg (pos);
+    std::string buffer(length, '\0');
+    strm.read(&buffer[0], length);
+    if (buffer.length() > length) { buffer.resize(length); }
+    strm.close();
+    return buffer;
+}
+//
+// ###############################################################
+// ###          END: read a piece from a text-file             ###
+// ###############################################################
+//

inc/helpers.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022-2024 plc-user
+ * Copyright (c) 2022-2025 plc-user
  *
  * Permission is hereby granted, free of charge, to any person
  * obtaining a copy of this software and associated documentation
@@ -29,6 +29,15 @@
 #include <iostream>     // for IO-Operations
 #include <cstdint>      // int8_t, ...
 
+// für die Terminal-Größe:
+#if defined(_WIN32)
+#define WIN32_LEAN_AND_MEAN
+#define VC_EXTRALEAN
+#include <windows.h>
+#elif defined(__linux__) || defined(__APPLE__)
+#include <sys/ioctl.h>
+#endif // Windows/Linux
+
 #define _DEBUG_ 0
 
 
@@ -62,6 +71,20 @@ std::string TextToEntity(const std::string& s);
 void CheckForDoubleString(std::string& s);
 
 
+//
+// --- determine the geometry of the terminal ----------------------------------
+//
+void get_terminal_size(size_t&, size_t&);
+size_t get_terminal_height(void);
+size_t get_terminal_width(void);
+
+
+//
+// --- returns a string of "length" characters around "position" ---------------
+//
+std::string ReadPieceOfFile(const std::string file, size_t pos, const size_t length);
+
+
 //
 // Funktionen, die vorher auch schon da waren
 //

main.cpp

@@ -37,10 +37,7 @@
 // +----------------------------------------------------------+
 //
 
-// own headers:
-#include "inc/pugixml/pugixml.hpp"
-#include "inc/helpers.h"
-#include "inc/elements.h"
+// own header(s):
 #include "main.h"
 
 
@@ -85,7 +82,10 @@ int main(int argc, char **argv)
     }
     // check the result of "doc.load"-Function
     if (!result){
-        std::cerr << "file \"" << ElementFile << "\" could not be loaded: " << result.description() << std::endl;
+        std::cerr << "File \"" << ElementFile << "\" could not be loaded: " << result.description() << std::endl;
+        std::cerr << "Check file up to byte-offset: " << result.offset << " -- content partly shown here:\n";
+        // try to read the corrupt part and output to stderr
+        std::cerr << "(...)" << ReadPieceOfFile(ElementFile, result.offset, (get_terminal_width()-10)) << "(...)\n\n";
         return -1;
     } else {
         if (_DEBUG_) std::cerr << "Element-File loaded successfully.\n";

main.h

@@ -34,12 +34,16 @@
 #include <getopt.h>     // for Commandline-Parameters
 #include <filesystem>   // for exe-filename
 #include <list>         // for list of UUIDs
+// project-includes
+#include "inc/pugixml/pugixml.hpp"
+#include "inc/helpers.h"
+#include "inc/elements.h"
 
 // =============================================================================
 // global variables
 // =============================================================================
 
-const std::string sVersion = "v0.5.1";
+const std::string sVersion = "v0.5.2";
 
 // the element-file to process:
 static std::string ElementFile       = "";