1 files changed, 128 insertions, 0 deletions
diff --git a/tests/sys/fs/tarfs/tarsum.c b/tests/sys/fs/tarfs/tarsum.c
new file mode 100644
index 000000000000..73ead2230a5e
--- /dev/null
+++ b/tests/sys/fs/tarfs/tarsum.c
@@ -0,0 +1,128 @@
+/*-
+ * Copyright (c) 2024 Klara, Inc.
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * This program reads a tarball from stdin, recalculates the checksums of
+ * all ustar records within it, and writes the result to stdout.
+ */
+
+#include <err.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+static bool opt_v;
+
+static int
+verbose(const char *fmt, ...)
+{
+	va_list ap;
+	int ret;
+
+	if (!opt_v)
+		return (0);
+	va_start(ap, fmt);
+	ret = vfprintf(stderr, fmt, ap);
+	va_end(ap);
+	return (ret);
+}
+
+static void
+tarsum(FILE *in, const char *ifn, FILE *out, const char *ofn)
+{
+	union {
+		uint8_t bytes[512];
+		struct {
+			uint8_t	prelude[148];
+			char	checksum[8];
+			uint8_t	interlude[101];
+			char	magic[6];
+			char	version[2];
+			char	postlude[];
+		};
+	} ustar;
+	unsigned long sum;
+	off_t offset = 0;
+	ssize_t ret;
+	size_t i;
+
+	for (;;) {
+		if ((ret = fread(&ustar, 1, sizeof(ustar), in)) < 0)
+			err(1, "%s", ifn);
+		else if (ret == 0)
+			break;
+		else if ((size_t)ret < sizeof(ustar))
+			errx(1, "%s: Short read", ifn);
+		if (strcmp(ustar.magic, "ustar") == 0 &&
+		    ustar.version[0] == '0' && ustar.version[1] == '0') {
+			verbose("header found at offset %#lx\n", offset);
+			verbose("current checksum %.*s\n",
+			    (int)sizeof(ustar.checksum), ustar.checksum);
+			memset(ustar.checksum, ' ', sizeof(ustar.checksum));
+			for (sum = i = 0; i < sizeof(ustar); i++)
+				sum += ustar.bytes[i];
+			verbose("calculated checksum %#lo\n", sum);
+			sprintf(ustar.checksum, "%#lo", sum);
+		}
+		if ((ret = fwrite(&ustar, 1, sizeof(ustar), out)) < 0)
+			err(1, "%s", ofn);
+		else if ((size_t)ret < sizeof(ustar))
+			errx(1, "%s: Short write", ofn);
+		offset += sizeof(ustar);
+	}
+	verbose("%lu bytes processed\n", offset);
+}
+
+static void
+usage(void)
+{
+	fprintf(stderr, "usage: tarsum [-v] [-o output] [input]\n");
+	exit(1);
+}
+
+int
+main(int argc, char *argv[])
+{
+	const char *ifn, *ofn = NULL;
+	FILE *in, *out;
+	int opt;
+
+	while ((opt = getopt(argc, argv, "o:v")) != -1) {
+		switch (opt) {
+		case 'o':
+			ofn = optarg;
+			break;
+		case 'v':
+			opt_v = true;
+			break;
+		default:
+			usage();
+		}
+	}
+	argc -= optind;
+	argv += optind;
+	if (argc == 0 || strcmp(*argv, "-") == 0) {
+		ifn = "stdin";
+		in = stdin;
+	} else if (argc == 1) {
+		ifn = *argv;
+		if ((in = fopen(ifn, "rb")) == NULL)
+			err(1, "%s", ifn);
+	} else {
+		usage();
+	}
+	if (ofn == NULL || strcmp(ofn, "-") == 0) {
+		ofn = "stdout";
+		out = stdout;
+	} else {
+		if ((out = fopen(ofn, "wb")) == NULL)
+			err(1, "%s", ofn);
+	}
+	tarsum(in, ifn, out, ofn);
+	return (0);
+}