Part 2 of prior commit

1 files changed, 78 insertions, 0 deletions

diff --git a/tdm/backend/daemon.c b/tdm/backend/daemon.c
new file mode 100644
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--- /dev/null
+++ b/tdm/backend/daemon.c
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+/*
+
+Copyright 1988, 1998  The Open Group
+Copyright 2000,2001,2003 Oswald Buddenhagen <ossi@kde.org>
+
+Permission to use, copy, modify, distribute, and sell this software and its
+documentation for any purpose is hereby granted without fee, provided that
+the above copyright notice appear in all copies and that both that
+copyright notice and this permission notice appear in supporting
+documentation.
+
+The above copyright notice and this permission notice shall be included
+in all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+OTHER DEALINGS IN THE SOFTWARE.
+
+Except as contained in this notice, the name of a copyright holder shall
+not be used in advertising or otherwise to promote the sale, use or
+other dealings in this Software without prior written authorization
+from the copyright holder.
+
+*/
+
+/*
+ * xdm - display manager daemon
+ * Author: Keith Packard, MIT X Consortium
+ */
+
+#include "dm.h"
+#include "dm_error.h"
+
+void
+BecomeDaemon( void )
+{
+	int pfd[2];
+
+	/*
+	 * fork so that the process goes into the background automatically. Also
+	 * has a nice side effect of having the child process get inherited by
+	 * init (pid 1).
+	 * Create a pipe and block on it, so the parent knows when the child is
+	 * done with detaching. This eliminates the possibility that the child
+	 * might get killed when the init script that's running xdm exits.
+	 */
+
+	if (pipe( pfd ))
+		pfd[0] = pfd[1] = -1; /* so what ...? */
+	switch (fork ()) {
+	case 0:
+		/* child */
+		break;
+	case -1:
+		/* error */
+		LogError( "Daemon fork failed: %m\n" );
+		break;
+
+	default:
+		/* parent */
+		close( pfd[1] );
+		read( pfd[0], &pfd[1] /* dummy */, 1 );
+		exit( 0 );
+	}
+
+	/* don't use daemon() - it doesn't buy us anything but an additional fork */
+
+	setsid();
+
+	close( pfd[0] );
+	close( pfd[1] ); /* tell parent that we're done with detaching */
+
+	chdir( "/" );
+}