Applied latest comment from danmar.

Author: damorinCan

lib/checkio.cpp

@@ -415,7 +415,13 @@ void CheckIO::seekOnAppendedFileError(const Token *tok)
 void CheckIO::ftellFileError(const Token *tok)
 {
     reportError(tok, Severity::portability,
-                "ftellTextModeFile", "According to Microsoft, the value returned by ftell may not reflect the physical byte offset for streams opened in text mode, because text mode causes carriage return-line feed translation. See also 7.21.9.4 in C11 standard.", CWE474, Certainty::normal);
+                "ftellTextModeFile", "The ftell function obtains the current value of the file position indicator"
+                " for the stream pointed to by stream. For a binary stream, the value is the number of characters"
+                " from the beginning of the file. For a text stream, its file position indicator contains unspecified"
+                " information, usable by the fseek function for returning the file position indicator for the stream"
+                " to its position at the time of the ftell call; the difference between two such return values is"
+                " not necessarily a meaningful measure of the number of characters written or read. See 7.21.9.4"
+                " in C11 standard.", CWE474, Certainty::normal);
 }
 
 void CheckIO::incompatibleFileOpenError(const Token *tok, const std::string &filename)

lib/checkio.h

@@ -1,6 +1,6 @@
 /* -*- C++ -*-
  * Cppcheck - A tool for static C/C++ code analysis
- * Copyright (C) 2007-2026 Cppcheck team.
+ * Copyright (C) 2007-2025 Cppcheck team.
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by

man/checkers/ftellTextModeFile.md

@@ -1,6 +1,6 @@
 # ftellModeTextFile 
 
-**Message**: According to Microsoft, the value returned by ftell may not reflect the physical byte offset for streams opened in text mode, because text mode causes carriage return-line feed translation. See also 7.21.9.4 in C11 standard.<br/>
+**Message**: The ftell function obtains the current value of the file position indicator for the stream pointed to by stream. For a binary stream, the value is the number of characters from the beginning of the file. For a text stream, its file position indicator contains unspecified information, usable by the fseek function for returning the file position indicator for the stream to its position at the time of the ftell call; the difference between two such return values is not necessarily a meaningful measure of the number of characters written or read. See a7.21.9.4 in C11 standard.<br/>
 **Category**: Portability<br/>
 **Severity**: Style<br/>
 **Language**: C/C++
@@ -26,8 +26,13 @@ Before:
      FILE *f = fopen("Example.txt", "rt");
      if (f)
      {
-        fseek(f, 0, SEEK_END);
-        printf( "Offset %d\n", ftell(f);
+        int position;
+        struct stat st;
+
+        position = fseek(f, 0, SEEK_END);
+        fstat(f, &st);
+        printf( "Position  %d\n", ftell(f);
+        printf( "File size %d\n, st.st_size);
         fclose(f);
      }
 

test/testio.cpp

@@ -711,12 +711,13 @@ class TestIO : public TestFixture {
               "     FILE *f = fopen(\"\", \"rt\");\n"
               "     if (f)\n"
               "     {\n"
+              "         extern long position;\n"
               "         fseek(f, 0, SEEK_END);\n"
-              "         (void)ftell(f);\n"
+              "         position = ftell(f);\n"
               "         fclose(f);\n"
               "     }\n"
               "}\n", dinit(CheckOptions, $.portability = true));
-        ASSERT_EQUALS("[test.cpp:6:16]: (portability) According to Microsoft, the value returned by ftell may not reflect the physical byte offset for streams opened in text mode, because text mode causes carriage return-line feed translation. See also 7.21.9.4 in C11 standard. [ftellTextModeFile]\n", errout_str());
+        ASSERT_EQUALS("[test.cpp:7:21]: (portability) The ftell function obtains the current value of the file position indicator for the stream pointed to by stream. For a binary stream, the value is the number of characters from the beginning of the file. For a text stream, its file position indicator contains unspecified information, usable by the fseek function for returning the file position indicator for the stream to its position at the time of the ftell call; the difference between two such return values is not necessarily a meaningful measure of the number of characters written or read. See 7.21.9.4 in C11 standard. [ftellTextModeFile]\n", errout_str());
     }