From: Mike Frysinger <vapier@gentoo.org>
Date: Wed, 26 Dec 2012 19:09:37 +0000 (-0500)
Subject: faster dd helper for erasing drivers
X-Git-Url: https://git.wh0rd.org/?a=commitdiff_plain;h=d777d1fb803a4adf084869a526eda1e6f282abc0;p=home.git

faster dd helper for erasing drivers
---

diff --git a/ddnuke.c b/ddnuke.c
new file mode 100644
index 0000000..3d01d36
--- /dev/null
+++ b/ddnuke.c
@@ -0,0 +1,91 @@
+/*
+ * released into the public domain
+ * written by Mike Frysinger <vapier>
+ */
+
+#define _FILE_OFFSET_BITS 64
+#define _LARGEFILE_SOURCE
+#define _LARGEFILE64_SOURCE
+#define _GNU_SOURCE
+
+#include <fcntl.h>
+#include <inttypes.h>
+#include <locale.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+static const char zero[1024 * 1024];
+
+#define errp(msg, args...) \
+	do { \
+		printf("%s: " msg ": %m\n", argv[0], ## args); \
+		return 1; \
+	} while (0)
+
+static unsigned long long mbps(struct timespec *stime, struct timespec *etime, off_t len)
+{
+	uint64_t dtime;
+	clock_gettime(CLOCK_MONOTONIC, etime);
+	dtime = ((etime->tv_sec - stime->tv_sec) * 1000 * 1000 * 1000) +
+		(etime->tv_nsec - stime->tv_nsec);
+	*stime = *etime;
+	return 1000 * len / dtime;
+}
+
+int main(int argc, char *argv[])
+{
+	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);
+
+	if (lseek(fd, offset, SEEK_SET) != offset)
+		errp("lseek(%"PRIu64"u) failed", offset);
+
+	unsigned long long speed = 0;
+	struct timespec stime, etime, itime;
+	clock_gettime(CLOCK_MONOTONIC, &stime);
+	itime = stime;
+
+	off_t pos = 0, last_pos = 0;
+	ssize_t ret;
+	int fsync_pos = 0;
+	while (1) {
+		ret = write(fd, zero, sizeof(zero));
+		pos += ret;
+		if (ret != sizeof(zero)) {
+			printf("\ngot back %zi (wanted %zu)\n%'llu MB/s over entire run\n",
+				ret, sizeof(zero), mbps(&itime, &etime, pos));
+			return 0;
+		}
+
+		printf("%'llu bytes (%'llu MB/s)%20s\r", (unsigned long long)pos, speed, "");
+
+		if ((++fsync_pos % 16) == 0) {
+			speed = mbps(&stime, &etime, pos - last_pos);
+			last_pos = pos;
+			fflush(stdout);
+			fsync(fd);
+		}
+	}
+
+	return 0;
+}