new check; file can not be opened for read and write access at the same time on different streams (misra rule 22.3)

lib/checkio.cpp

@@ -106,6 +106,7 @@ struct Filepointer {
     nonneg int op_indent;
     enum class AppendMode { UNKNOWN_AM, APPEND, APPEND_EX };
     AppendMode append_mode;
+    std::string filename;
     explicit Filepointer(OpenMode mode_ = OpenMode::UNKNOWN_OM)
         : mode(mode_), mode_indent(0), lastOperation(Operation::NONE), op_indent(0), append_mode(AppendMode::UNKNOWN_AM) {
     }
@@ -174,6 +175,7 @@ void CheckIO::checkFileUsage()
             } else if (Token::Match(tok, "%name% (") && tok->previous() && (!tok->previous()->isName() || Token::Match(tok->previous(), "return|throw"))) {
                 std::string mode;
                 const Token* fileTok = nullptr;
+                const Token* fileNameTok = nullptr;
                 Filepointer::Operation operation = Filepointer::Operation::NONE;
 
                 if ((tok->str() == "fopen" || tok->str() == "freopen" || tok->str() == "tmpfile" ||
@@ -187,6 +189,8 @@ void CheckIO::checkFileUsage()
                         mode = "wb+";
                     fileTok = tok->tokAt(-2);
                     operation = Filepointer::Operation::OPEN;
+                    if (Token::Match(tok, "fopen ( %str% ,"))
+                        fileNameTok = tok->tokAt(2);
                 } else if (windows && Token::Match(tok, "fopen_s|freopen_s|_wfopen_s|_wfreopen_s ( & %name%")) {
                     const Token* modeTok = tok->tokAt(2)->nextArgument()->nextArgument();
                     if (modeTok && modeTok->tokType() == Token::eString)
@@ -266,10 +270,21 @@ void CheckIO::checkFileUsage()
                 if (filepointers.find(fileTok->varId()) == filepointers.end()) { // function call indicates: Its a File
                     filepointers.insert(std::make_pair(fileTok->varId(), Filepointer(OpenMode::UNKNOWN_OM)));
                 }
+
                 Filepointer& f = filepointers[fileTok->varId()];
 
                 switch (operation) {
                 case Filepointer::Operation::OPEN:
+                    if (fileNameTok) {
+                        for (std::map<int, Filepointer>::const_iterator it = filepointers.cbegin(); it != filepointers.cend(); ++it) {
+                            const Filepointer &fptr = it->second;
+                            if (fptr.filename == fileNameTok->str() && (fptr.mode == OpenMode::RW_MODE || fptr.mode == OpenMode::WRITE_MODE))
+                                incompatibleFileOpenError(tok, fileNameTok->str());
+                        }
+
+                        f.filename = fileNameTok->str();
+                    }
+
                     f.mode = getMode(mode);
                     if (mode.find('a') != std::string::npos) {
                         if (f.mode == OpenMode::RW_MODE)
@@ -370,6 +385,12 @@ void CheckIO::seekOnAppendedFileError(const Token *tok)
                 "seekOnAppendedFile", "Repositioning operation performed on a file opened in append mode has no effect.", CWE398, Certainty::normal);
 }
 
+void CheckIO::incompatibleFileOpenError(const Token *tok, const std::string &filename)
+{
+    reportError(tok, Severity::warning,
+                "incompatibleFileOpen", "The file '" + filename + "' is opened for read and write access at the same time on different streams", CWE664, Certainty::normal);
+}
+
 
 //---------------------------------------------------------------------------
 // scanf without field width limits can crash with huge input data

lib/checkio.h

@@ -114,6 +114,7 @@ private:
     void writeReadOnlyFileError(const Token *tok);
     void useClosedFileError(const Token *tok);
     void seekOnAppendedFileError(const Token *tok);
+    void incompatibleFileOpenError(const Token *tok, const std::string &filename);
     void invalidScanfError(const Token *tok);
     void wrongPrintfScanfArgumentsError(const Token* tok,
                                         const std::string &functionName,
@@ -145,6 +146,7 @@ private:
         c.writeReadOnlyFileError(nullptr);
         c.useClosedFileError(nullptr);
         c.seekOnAppendedFileError(nullptr);
+        c.incompatibleFileOpenError(nullptr, "tmp");
         c.invalidScanfError(nullptr);
         c.wrongPrintfScanfArgumentsError(nullptr, "printf",3,2);
         c.invalidScanfArgTypeError_s(nullptr,  1, "s", nullptr);
@@ -174,6 +176,7 @@ private:
                "- File input/output without positioning results in undefined behaviour\n"
                "- Read to a file that has only been opened for writing (or vice versa)\n"
                "- Repositioning operation on a file opened in append mode\n"
+               "- The same file can't be open for read and write at the same time on different streams\n"
                "- Using fflush() on an input stream\n"
                "- Invalid usage of output stream. For example: 'std::cout << std::cout;'\n"
                "- Wrong number of arguments given to 'printf' or 'scanf;'\n";

test/testio.cpp

@@ -45,6 +45,7 @@ private:
         TEST_CASE(fileIOwithoutPositioning);
         TEST_CASE(seekOnAppendedFile);
         TEST_CASE(fflushOnInputStream);
+        TEST_CASE(incompatibleFileOpen);
 
         TEST_CASE(testScanf1); // Scanf without field limiters
         TEST_CASE(testScanf2);
@@ -715,7 +716,13 @@ private:
         ASSERT_EQUALS("", errout.str());
     }
 
-
+    void incompatibleFileOpen() {
+        check("void foo() {\n"
+              "    FILE *f1 = fopen(\"tmp\", \"wt\");\n"
+              "    FILE *f2 = fopen(\"tmp\", \"rt\");\n"
+              "}");
+        ASSERT_EQUALS("[test.cpp:3]: (warning) The file '\"tmp\"' is opened for read and write access at the same time on different streams\n", errout.str());
+    }
 
 
     void testScanf1() {