When compiling on newer versions of gcc (in particular, Ubuntu/Linaro, gcc 4.4.4) with -Wall, I receive the following warning when including G4RunManager: /home/mgmarino/software/geant4/include/geant4/G4RunManager.hh: In member function ‘void G4RunManager::SetRandomNumberStoreDir(const G4String&)’: /home/mgmarino/software/geant4/include/geant4/G4RunManager.hh:358: warning: ignoring return value of ‘int system(const char*)’, declared with attribute warn_unused_result The relevant code: 346 inline void SetRandomNumberStoreDir(const G4String& dir) 347 { 348 G4String dirStr = dir; 349 if( dirStr(dirStr.length()-1) != '/' ) dirStr += "/"; 350 #ifndef WIN32 351 G4String shellCmd = "mkdir -p "; 352 #else 353 std::replace(dirStr.begin(), dirStr.end(),'/','\\'); 354 G4String shellCmd = "mkdir "; 355 #endif 356 shellCmd += dirStr; 357 randomNumberStatusDir = dirStr; 358 system(shellCmd); 359 } This warning is in principle valid on all systems. When the directory is set, it is passed to a forked shell via the system command. However, the return of the system command is not checked to ensure that the forking and the mkdir command have completed successfully. This could introduce issues when users request directories for which they do not have the correct permissions or when some other unforeseen failure occurs, as the SetRandomNumberStoreDir function assumes that the system call has succeeded. I think there are two possible solutions to this, I'm afraid neither is completely simple given portability issues: 1. Check the return value of system. This is complicated due to the fact that the return value is platform dependent and needs to be handled to determine if the error came from the forking or from the 'mkdir' call. 2. Use POSIX and Windows 'mkdir' and 'CreateDirectory' functions directly. This would be my suggested method since it avoids the system call altogether. However, the recursive generation of directories would need to be handled manually. Both solutions would also notify the user if the call has failed and output any available system error (strerror?). Only successful calls would result in randomNumberStatusDir being set.
Thank you for addressing this. We will look into the potential solution.
Thank you once again for pointing this out. We modify the line 354 to G4String shellCmd = "if not exist " + dirStr + " mkdir "; which should fix the problem. We will release this fix with the next patch.
Thanks for having a look at this. I'm afraid this fix won't take care of the warning message or check whether the call to 'system' failed. That is, the return value of 'system' (line 358) should be checked to ensure that it has in fact succeeded. It is still possible for the call to fail if the directory does not exist but the user doesn't have the correct permissions for the directory. In our code, we have the following to check, but we only run on linux and mac os x: int system_return = system(pscommand); if ( system_return == -1 || system_return > 0 ) { // ps return 0 if success, system could return -1 or 127 on POSIX systems on failure. std::cout << "Error calling ps to determine memory usage information." << std::endl; std::cout << " Return value: " << system_return << std::endl; } The difficulty is that for further os support, the return value of system is platform and os dependent: http://www.cplusplus.com/reference/clibrary/cstdlib/system/
