From d8ceb2d61d353617ea72a576566bb969b60bf0fb Mon Sep 17 00:00:00 2001
From: Mike Frysinger <vapier@gentoo.org>
Date: Sat, 4 Apr 2015 22:02:05 -0400
Subject: [PATCH] ddnuke: add random data options

---
 ddnuke.c | 100 +++++++++++++++++++++++++++++++++++++------------------
 1 file changed, 68 insertions(+), 32 deletions(-)

diff --git a/ddnuke.c b/ddnuke.c
index 94691b3..03ac789 100644
--- a/ddnuke.c
+++ b/ddnuke.c
@@ -15,17 +15,17 @@
 #include <fcntl.h>
 #include <inttypes.h>
 #include <locale.h>
+#include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
+#include <sysexits.h>
 #include <time.h>
 #include <unistd.h>
 #include <sys/ioctl.h>
 #include <sys/stat.h>
 #include <linux/fs.h>
 
-static const char zero[1024 * 1024];
-
 #define errp(msg, args...) \
 	do { \
 		printf("%s: " msg ": %m\n", program_invocation_short_name, ## args); \
@@ -66,32 +66,12 @@ static off_t get_size(int fd)
 	errp("unknown type of file");
 }
 
-int main(int argc, char *argv[])
+static void nuke(int fd, off_t offset, off_t max_size, unsigned char pattern)
 {
-	off_t offset = 0;
-	const char *file;
-
-	setlocale(LC_NUMERIC, "en_US");
-
-	switch (argc) {
-	case 3:
-		offset = atoll(argv[2]);
-	case 2:
-		file = argv[1];
-		break;
-	default:
-		puts("Usage: ddnuke <dev> [offset in bytes]");
-		return 1;
-	}
-
-	int fd = open(file, O_WRONLY);
-	if (fd == -1)
-		errp("open(%s) failed", file);
-
-	off_t max_size = get_size(fd);
-
-	if (lseek(fd, offset, SEEK_SET) != offset)
-		errp("lseek(%"PRIu64"u) failed", offset);
+	static char mem[1024 * 1024];
+	memset(mem, pattern, sizeof(mem));
+	if (pattern)
+		printf("Writing 0x%X to the output\n", pattern);
 
 	unsigned long long speed = 0;
 	struct timespec stime, etime, itime;
@@ -102,12 +82,13 @@ int main(int argc, char *argv[])
 	ssize_t ret;
 	int fsync_pos = 0;
 	while (pos < max_size) {
-		ret = write(fd, zero, sizeof(zero));
+		/* This will round up to sizeof(mem) ... */
+		ret = write(fd, mem, sizeof(mem));
 		pos += ret;
-		if (ret != sizeof(zero)) {
+		if (ret != sizeof(mem)) {
 			printf("\nread() returned %zi (wanted %zu)\n%'llu MB/s over entire run\n",
-				ret, sizeof(zero), mbps(&itime, &etime, pos));
-			return 0;
+				ret, sizeof(mem), mbps(&itime, &etime, pos));
+			return;
 		}
 
 		printf("%'llu bytes %u%% (%'llu MB/s)%20s\r", (unsigned long long)pos,
@@ -122,5 +103,60 @@ int main(int argc, char *argv[])
 	}
 
 	printf("\n");
-	return 0;
+}
+
+static void usage(int status)
+{
+	fprintf(
+		status ? stderr : stdout,
+		"Usage: ddnuke [options] <dev>\n"
+		"\n"
+		"Options:"
+		" -o <offset>   Position to start writing\n"
+		" -r            Write random garbage to the device\n"
+	);
+	exit(status);
+}
+
+int main(int argc, char *argv[])
+{
+	off_t offset = 0;
+	const char *file;
+	bool random = false;
+	int o;
+
+	setlocale(LC_NUMERIC, "en_US");
+
+	while ((o = getopt(argc, argv, "ho:r")) != -1) {
+		switch (o) {
+		case 'o':
+			offset = atoll(optarg);
+			break;
+		case 'r':
+			random = true;
+			break;
+		case 'h': usage(EX_OK);
+		default:  usage(EX_USAGE);
+		}
+	}
+	if (argc != optind + 1)
+		usage(EX_USAGE);
+	file = argv[optind];
+
+	int fd = open(file, O_WRONLY|O_CLOEXEC);
+	if (fd == -1)
+		errp("open(%s) failed", file);
+
+	off_t max_size = get_size(fd);
+
+	if (lseek(fd, offset, SEEK_SET) != offset)
+		errp("lseek(%"PRIu64"u) failed", offset);
+
+	nuke(fd, offset, max_size, 0x00);
+	if (random) {
+		nuke(fd, offset, max_size, 0xaa);
+		nuke(fd, offset, max_size, 0x55);
+	}
+
+	return EX_OK;
 }
-- 
2.39.2