Re: [PATCH v2] fix start_command() bug when stdin is closed

Paolo Bonzini schrieb:

There is a problem in the use of dup2+close in start_command()
when one or more of file descriptors 0/1/2 are closed.

"Karl Chen pointed out a problem..." (just to give due credit).

 int start_command(struct child_process *cmd)
 {
 	int need_in, need_out, need_err;
 	int fdin[2], fdout[2], fderr[2];
 
 	/*
+	 * Make sure that all file descriptors <= 2 are open, otherwise we
+	 * mess them up when dup'ing pipes onto stdin/stdout/stderr.  Since
+	 * we are at it, open a file descriptor on /dev/null to use it later.
+	 */
+	if (devnull_fd == -1)
+	  {
+	    devnull_fd = open("/dev/null", O_RDWR);
+	    while (devnull_fd >= 0 && devnull_fd <= 2)
+	      devnull_fd = dup(devnull_fd);
+	    if (devnull_fd == -1)
+	      die("opening /dev/null failed (%s)", strerror(errno));
+	  }

Except for the insane GNU style indentation ;-) this makes a lot of sense.

Acked-by: Johannes Sixt <redacted>

The changes to the MINGW32 section are good (they pass the test suite).
Thanks for taking care of that.

-- Hannes