1 files changed, 109 insertions, 0 deletions
diff --git a/tests/zfs-tests/cmd/get_diff/get_diff.c b/tests/zfs-tests/cmd/get_diff/get_diff.c
new file mode 100644
index 000000000000..2799f46b0747
--- /dev/null
+++ b/tests/zfs-tests/cmd/get_diff/get_diff.c
@@ -0,0 +1,109 @@
+/*
+ * This file and its contents are supplied under the terms of the
+ * Common Development and Distribution License ("CDDL"), version 1.0.
+ * You may only use this file in accordance with the terms of version
+ * 1.0 of the CDDL.
+ *
+ * A full copy of the text of the CDDL should have accompanied this
+ * source.  A copy of the CDDL is also available via the Internet at
+ * http://www.illumos.org/license/CDDL.
+ */
+
+/*
+ * Copyright (c) 2018 by Delphix. All rights reserved.
+ */
+
+#include <stdio.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+#include <sys/param.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <errno.h>
+
+static void
+usage(char *msg, int exit_value)
+{
+	(void) fprintf(stderr, "get_diff file redacted_file\n");
+	(void) fprintf(stderr, "%s\n", msg);
+	exit(exit_value);
+}
+
+/*
+ * This utility compares two files, an original and its redacted counterpart
+ * (in that order). It compares the files 512 bytes at a time, printing out
+ * any ranges (as offset and length) where the redacted file does not match
+ * the original. This output is used to verify that the expected ranges of
+ * a redacted file do not contain the original data.
+ */
+int
+main(int argc, char *argv[])
+{
+	off_t		diff_off = 0, diff_len = 0, off = 0;
+	int		fd1, fd2;
+	char		*fname1, *fname2;
+	char		buf1[DEV_BSIZE], buf2[DEV_BSIZE];
+	ssize_t		bytes;
+
+	if (argc != 3)
+		usage("Incorrect number of arguments.", 1);
+
+	if ((fname1 = argv[1]) == NULL)
+		usage("Filename missing.", 1);
+	if ((fd1 = open(fname1, O_LARGEFILE | O_RDONLY)) < 0) {
+		perror("open1 failed");
+		exit(1);
+	}
+
+	if ((fname2 = argv[2]) == NULL)
+		usage("Redacted filename missing.", 1);
+	if ((fd2 = open(fname2, O_LARGEFILE | O_RDONLY)) < 0) {
+		perror("open2 failed");
+		exit(1);
+	}
+
+	while ((bytes = pread(fd1, buf1, DEV_BSIZE, off)) > 0) {
+		if (pread(fd2, buf2, DEV_BSIZE, off) < 0) {
+			if (errno == EIO) {
+				/*
+				 * A read in a redacted section of a file will
+				 * fail with EIO. If we get EIO, continue on
+				 * but ensure that a comparison of buf1 and
+				 * buf2 will fail, indicating a redacted block.
+				 */
+				buf2[0] = ~buf1[0];
+			} else {
+				perror("pread failed");
+				exit(1);
+			}
+		}
+		if (memcmp(buf1, buf2, bytes) == 0) {
+			if (diff_len != 0) {
+				(void) fprintf(stdout, "%lld,%lld\n",
+				    (long long)diff_off, (long long)diff_len);
+				assert(off == diff_off + diff_len);
+				diff_len = 0;
+			}
+			diff_off = 0;
+		} else {
+			if (diff_len == 0)
+				diff_off = off;
+			assert(off == diff_off + diff_len);
+			diff_len += bytes;
+		}
+		off += bytes;
+	}
+
+	if (diff_len != 0 && diff_len != 0) {
+		(void) fprintf(stdout, "%lld,%lld\n", (long long)diff_off,
+		    (long long)diff_len);
+	}
+
+	(void) close(fd1);
+	(void) close(fd2);
+
+	return (0);
+}