discover: Fix CDROM handling

Currently, we don't handle CDROM devices well; we'll try to mount on
boot, and not detect any media changes. Also, the default rules shipping
with udev will put the CDROM tray into a locked state, blocking eject
from working.

This change adds a set of cdrom utility functions, which the udev code
can use to properly initialise cdrom devices and handle eject and media
change requests.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

1 files changed, 81 insertions, 0 deletions

diff --git a/discover/cdrom.c b/discover/cdrom.c
new file mode 100644
index 0000000..0e88301
--- /dev/null
+++ b/discover/cdrom.c
@@ -0,0 +1,81 @@
+#include <stdlib.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <limits.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <linux/cdrom.h>
+
+#include <log/log.h>
+
+#include "cdrom.h"
+
+static int cdrom_open(const char *devpath, const char *loc)
+{
+	int fd;
+
+	fd = open(devpath, O_RDONLY | O_NONBLOCK);
+	if (fd < 0)
+		pb_log("%s: can't open %s: %s\n", loc, devpath,
+				strerror(errno));
+
+	return fd;
+}
+
+void cdrom_init(const char *devpath)
+{
+	int fd, rc;
+
+	fd = cdrom_open(devpath, __func__);
+	if (fd < 0)
+		return;
+
+	/* We disable autoclose so that any attempted mount() operation doesn't
+	 * close the tray, and disable CDO_LOCK to prevent the lock status
+	 * changing on open()/close()
+	 */
+	rc = ioctl(fd, CDROM_CLEAR_OPTIONS, CDO_LOCK | CDO_AUTO_CLOSE);
+	if (rc < 0)
+		pb_debug("%s: CLEAR CDO_LOCK|CDO_AUTO_CLOSE failed: %s\n",
+				__func__, strerror(errno));
+
+	close(fd);
+}
+
+bool cdrom_media_present(const char *devpath)
+{
+	int fd, rc;
+
+	fd = cdrom_open(devpath, __func__);
+	if (fd < 0)
+		return false;
+
+	rc = ioctl(fd, CDROM_DRIVE_STATUS, CDSL_CURRENT);
+
+	close(fd);
+
+	return rc == CDS_DISC_OK;
+}
+
+void cdrom_eject(const char *devpath)
+{
+	int fd, rc;
+
+	fd = cdrom_open(devpath, __func__);
+	if (fd < 0)
+		return;
+
+	/* unlock cdrom device */
+	rc = ioctl(fd, CDROM_LOCKDOOR, 0);
+	if (rc < 0)
+		pb_log("%s: CDROM_LOCKDOOR(unlock) failed: %s\n",
+				__func__, strerror(errno));
+
+	rc = ioctl(fd, CDROMEJECT, 0);
+	if (rc < 0)
+		pb_log("%s: CDROM_EJECT failed: %s\n",
+				__func__, strerror(errno));
+	close(fd);
+}
+