PIN tool doesn't write to stdout or sterr on windows

Question

I'm writing a pin tool (Windows, x64, PIN 3.18), and it starts like this:

int main(int argc, char *argv[]) {
    std::cerr << "Initializing..." << std::endl;

This is how I'm calling the tool: C:\pin\intel64\bin\pin -t C:\pin\source\tools\MyPinTool\x64\Release\MyPinTool.dll -- mspaint.exe

Nothing is ever printed to stderr. fprintf(stderr, ...) also prints nothing. stdout seems to behave in the same way. The tool itself works, and if I instead fprintf to a file, that works as well. It doesn't seem to me like I'm deviating from the docs examples.

I also searched in the docs for stuff related to output with no luck.

Why is nothing getting printed?

Answer 1

The pintool is a DLL which is injected into the target process and runs in its context. Since mspaint is a GUI program, it does not have a console to which print output could go. You have the following options:

1. Change mspaint.exe subsystem to console so that a console window is allocated on startup.
2. Call AllocConsole() in your pintool and set up stdout/stderr to go there (not sure about the details here).
3. Use an explicitly opened log file for output instead of stderr.