Re: [PATCH v2 06/14] mingw: use real pid

On Montag, 18. Januar 2010, Erik Faye-Lund wrote:

On Sat, Jan 16, 2010 at 10:12 AM, Erik Faye-Lund wrote:

quoted

On Sat, Jan 16, 2010 at 9:03 AM, Johannes Sixt [off-list ref] wrote:

quoted

On Freitag, 15. Januar 2010, Erik Faye-Lund wrote:

quoted

No. If I do, the pid becomes invalid after the process is finished,
and waitpid won't work. I couldn't find anywhere were we actually were
closing the handle, even after it was finished. So I don't think we
leak any more than we already did (for non-daemon purposes).

Previously, this handle was closed by _cwait() (it was the "pid"), so we
didn't leak it.

Oh, I see. My planned route with this (before I looked for where the
handle was closed), was to maintain some sort of list of each started
PID and their handle, and lookup in that list instead of using
OpenProcess. I guess that would solve the problem here, but it feels a
bit nasty. Not as nasty as introducing a leak, though.

What I had in mind was something along these lines:

Given that that the process ID is the user-visible (and system-wide unique) 
identifier of a process, this looks like the only reasonable way to go. Your 
implementation looks good as well.

+	/* store process handle */

	/*
	 * The process ID is the human-readable identifier of the process
	 * that we want to present in log and error messages. The handle
	 * is not useful for this purpose. But we cannot close it, either,
	 * because it is not possible to turn a process ID into a process
	 * handle after the process terminated.
	 * Keep the handle in a list for waitpid.
	 */

+	num_pinfo++;
+	pinfo = xrealloc(pinfo, sizeof(struct pid_info) * num_pinfo);
+	pinfo[num_pinfo - 1].pid = pi.dwProcessId;
+	pinfo[num_pinfo - 1].proc = pi.hProcess;
+
 	return (pid_t)pi.dwProcessId;

-- Hannes