From 73a564c7678e492f557d2e8ebfa9829f5df504ac Mon Sep 17 00:00:00 2001
From: Thomas Schmitt <scdbackup@gmx.net>
Date: Wed, 18 Apr 2007 10:32:23 +0000
Subject: [PATCH] Program for probing access to device files. By Ted Ts'o with
 modifications by me.

---
 libburn/trunk/test/open-cd-excl.c | 137 ++++++++++++++++++++++++++++++
 1 file changed, 137 insertions(+)
 create mode 100644 libburn/trunk/test/open-cd-excl.c

diff --git a/libburn/trunk/test/open-cd-excl.c b/libburn/trunk/test/open-cd-excl.c
new file mode 100644
index 00000000..34404e21
--- /dev/null
+++ b/libburn/trunk/test/open-cd-excl.c
@@ -0,0 +1,137 @@
+/*
+ * open-cd-excl.c --- This program tries to open a block device
+ * by various exclusive and non-exclusive gestures in order to explore
+ * their impact on running CD/DVD recordings.
+ *
+ * Copyright 2007, by Theodore Ts'o.
+ *
+ * Detail modifications 2007, by Thomas Schmitt.
+ * 
+ * %Begin-Header%
+ * This file may be redistributed under the terms of the GNU Public
+ * License.
+ * %End-Header%
+ */
+
+#define _GNU_SOURCE /* for O_LARGEFILE *//*ts A70417: or _LARGEFILE64_SOURCE */
+
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <fcntl.h>
+#include <getopt.h>
+
+const char *progname;
+
+static void usage(void)
+{
+	fprintf(stderr, "Usage: %s [-feirw] device\n", progname);
+	exit(1);
+}
+
+/* ts A70417: added parameter do_rdwr */
+static void init_flock(struct flock *fl, int do_rdwr)
+{
+	memset(fl, 0, sizeof(struct flock));
+	if (do_rdwr)
+		fl->l_type = F_WRLCK;
+	else
+		fl->l_type = F_RDLCK;
+	fl->l_whence = SEEK_SET;
+	fl->l_start = 0;
+	fl->l_len = 0;
+}
+
+int main(int argc, char **argv)
+{
+	struct flock	fl;
+	char	*device_name;
+	int	fd, c, f_opt = 0, do_rdwr = 0, end_immediately = 0;
+	int	flags = O_NONBLOCK|O_LARGEFILE;
+	
+	progname = argv[0];
+
+	/* ts A70417: added -w and -r */
+	while ((c = getopt (argc, argv, "feirw")) != EOF) {
+		switch (c) {
+		case 'e':
+			flags |= O_EXCL;
+			break;
+		case 'f':
+			f_opt++;
+			break;
+		case 'i':
+			end_immediately = 1;
+			break;
+		case 'r':
+			do_rdwr = 0;
+			break;
+		case 'w':
+			do_rdwr = 1;
+			break;
+		case '?':
+			usage();
+			exit(1);
+		}
+	}
+
+	if (optind == argc)
+		usage();
+	device_name = argv[optind++];
+
+	/* ts A70417 : made read-write adjustable independently of f_opt */
+	if (do_rdwr) {
+		flags |= O_RDWR;
+		printf("Using O_RDWR\n");
+	} else {
+		flags |= O_RDONLY;
+		printf("Using O_RDONLY\n");
+	}
+
+	if (flags & O_EXCL)
+		printf("Trying to open %s with O_EXCL ...\n", device_name);
+	fd = open(device_name, flags, 0);
+	if (fd < 0) {
+		perror("open");
+		printf("failed\n");
+		exit(1);
+	}
+	if (flags & O_EXCL)
+		printf("succeeded\n");
+		
+	if (f_opt) {
+		init_flock(&fl, do_rdwr);
+		if (fcntl(fd, F_GETLK, &fl) < 0) {
+			perror("fcntl: F_GETLK: ");
+			exit(1);
+		}
+		printf("fcntl lock apparently %sLOCKED\n", 
+		       (fl.l_type == F_UNLCK) ? "NOT " : "");
+
+		/* ts A70418: do not try to lock if it is already locked */
+		if (fl.l_type != F_UNLCK) {
+			printf("failed\n");
+			exit(1);
+		}
+
+		init_flock(&fl, do_rdwr);
+		printf("Trying to grab fcntl lock...\n");
+		if (fcntl(fd, F_SETLKW, &fl) < 0) {
+			perror("fcntl: F_SETLKW: ");
+			exit(1);
+		}
+		printf("succeeded\n");
+	}
+
+	/* ts A70417: added end_immediately */
+	printf("Holding %s open.\n", device_name);
+	if (end_immediately)
+		exit(0);
+	printf("Press ^C to exit.\n");
+	while (1) {
+		sleep(300);
+	} 
+	/* NOTREACHED */
+	return 0;
+}