Question

In the following code if I comment out the call to “GetCurrentDirectory” everything works fine, but if I don’t then the code breaks after it, no child windows show up, but the program don’t crash. The compiler doesn’t give any error.

 char *iniFilePath;
 int lenWritten = GetCurrentDirectory( MAX_PATH, iniFilePath );
 if( lenWritten )
 {
     lstrcat( iniFilePath, iniFileName.c_str() );
     char *buffer;
     GetPrivateProfileString( iniServerSectionName.c_str(), serverIp.c_str(), "", buffer, MAX_PATH, iniFilePath );// server ip
     MessageBox( 0, buffer, 0, 0 );
 }
 else
 {
     MessageBox( 0,0,0,0 );
 }

Answer 1

iniFilePath is an unintialised pointer which GetCurrentDirectory() is attempting to write to, causing undefined behaviour. GetCurrentDirectory() does not allocate a buffer for the caller: it must be provided.

Change to:

char iniFilePath[MAX_PATH]; // or similar.

Instead of using lstrcat(), which has Warning Do not use message on its reference page, construct the path use a std::string instead to avoid potential buffer overruns:

const std::string full_file_path(std::string(iniFilePath) + "/" + iniFileName);

Note similar issue with buffer, as pointed out by Wimmel.