1 files changed, 137 insertions, 0 deletions
diff --git a/fs/alternate.c b/fs/alternate.c
new file mode 100644
index 0000000..942f3b9
--- /dev/null
+++ b/fs/alternate.c
@@ -0,0 +1,137 @@
+/******************************************************************************
+*******************************************************************************
+**
+**    Copyright 2001 Sistina Software, Inc.
+**
+**    This is free software released under the GNU General Public License.
+**    There is no warranty for this software.  See the file COPYING for
+**    details.
+**
+*******************************************************************************
+******************************************************************************/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#define die(fmt, args...) \
+{ \
+  fprintf(stderr, "%s: ", prog_name); \
+  fprintf(stderr, fmt, ##args); \
+  exit(EXIT_FAILURE); \
+}
+
+#define do_lseek(fd, off) \
+{ \
+  if (lseek((fd), (off), SEEK_SET) != (off)) \
+    die("bad seek: %s on line %d of file %s\n", \
+        strerror(errno),__LINE__, __FILE__); \
+}
+
+#define do_read(fd, buff, len) \
+{ \
+  if (read((fd), (buff), (len)) != (len)) \
+    die("bad read: %s on line %d of file %s\n", \
+        strerror(errno), __LINE__, __FILE__); \
+}
+
+#define do_write(fd, buff, len) \
+{ \
+  if (write((fd), (buff), (len)) != (len)) \
+    die("bad write: %s on line %d of file %s\n", \
+        strerror(errno), __LINE__, __FILE__); \
+}
+
+#define BLOCK_SIZE (512)
+
+char *prog_name;
+
+unsigned int wait;
+unsigned int delay = 0;
+
+int main(int argc, char *argv[])
+{
+	int cont = 1;
+	int optchar;
+	int fd;
+	char *filename;
+	char buf[BLOCK_SIZE];
+	unsigned long long offset;
+	unsigned long long num, last_num = 0;
+	unsigned int id, clients;
+	unsigned long long skip = 0;
+	unsigned int iterations = 0;
+	unsigned int delay = 0;
+
+	prog_name = argv[0];
+
+	while (cont) {
+		optchar = getopt(argc, argv, "i:s:");
+		switch (optchar) {
+		case 'i':
+			iterations = atoi(optarg);
+			break;
+		case 's':
+			delay = atoi(optarg);
+			break;
+		case 'h':
+			die("[-i iterations] [-s usleep] filename offset id clients\n");
+		case EOF:
+			cont = 0;
+			break;
+		}
+	}
+
+	if (argc - optind < 4)
+		die("[-i iterations] [-s usleep] filename offset id clients\n");
+
+	filename = argv[optind];
+	offset = atoll(argv[optind + 1]);
+	id = atoi(argv[optind + 2]);
+	clients = atoi(argv[optind + 3]);
+
+	fd = open(filename, O_RDWR | O_CREAT, 0644);
+	if (fd < 0)
+		die("can't open file %s: %s\n", argv[1], strerror(errno));
+
+	for (;;) {
+		do_lseek(fd, offset);
+
+		do_read(fd, buf, BLOCK_SIZE);
+
+		num = atoll(buf);
+		if (num % clients == id) {
+			num++;
+			sprintf(buf, "%llu\n", num);
+			printf("%llu %llu\n", num, skip);
+
+			if (last_num && last_num + clients != num)
+				die("bad\n");
+
+			do_lseek(fd, offset);
+
+			do_write(fd, buf, BLOCK_SIZE);
+
+			if (iterations && num >= iterations)
+				break;
+
+			last_num = num;
+			skip = 0;
+		} else {
+			skip++;
+		}
+
+		if (delay)
+			usleep(delay);
+	}
+
+	close(fd);
+
+	exit(EXIT_SUCCESS);
+}
+