Win32 ReadFile hangs when reading from pipe

Question

I am creating a child process, and reading its output. My code works fine when the child process creates output (cmd /c echo Hello World), however ReadFile will

Answer 1

You could use PeekNamedPipe in a loop like this:

for (;;)
{
    DWORD bytesAvail = 0;
    if (!PeekNamedPipe(stdoutPipeRead, NULL, 0, NULL, &bytesAvail, NULL)) {
        std::cout << "Failed to call PeekNamedPipe" << std::endl;
    }
    if (bytesAvail) {
        CHAR buf[BUFSIZE];
        DWORD n;
        BOOL success = ReadFile(stdoutPipeRead, buf, BUFSIZE, &n, NULL);
        if (!success || n == 0) {
            std::cout << "Failed to call ReadFile" << std::endl;
        }
        std::cout << std::string(buf, buf + n);
    }
}