I need to send data from child processes to parent. Some of this data is HTML, plain text, etc. but it may also be necessary send image data, zip file data, etc.
As I understand it, anonymous pipes use the child process standard input and standard output. Conventionally stdin and stdout only convey textual data: would there be any problem with sending non printable characters using this mechanism?
There is no relation between anonymous pipes and stdin/out. As one process has only one stdin/out, you could create only one anonymous pipe per process that way, which sounds stupid, doesn't it? You can redirect stdin/out of a child process to the pipe, yes. But you don't have to, if the child process is able to report itself by another means (like logfile or network activity). A call to CreatePipe gives you reading and writing handles and it's up to you how you use them. Sending arbitrary binary data is indeed possible. Anonymous pipe is in no way different from named pipe in that respect.
Even if you do choose to use stdin/stdout redirection to pass the pipe handle(s) to the child process, you shouldn't have any problems provided the child process uses the Windows API to send the data rather than the C runtime library functions.
That is, WriteFile will work perfectly, but printf would not be a good idea.
You can use GetStdHandle to get the handle(s) to the pipe(s) for use with the Windows API functions.
