Add a single, central hex blob decoder

Since we need it twice (once for tar, once for the filemap xattr
parser), add a single, central implementation to libutil, add a
unit test for that implementation and then use it in both libtar
and gensquashfs.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

1 files changed, 66 insertions, 0 deletions

diff --git a/tests/libutil/hex_decode.c b/tests/libutil/hex_decode.c
new file mode 100644
index 0000000..21ac4e7
--- /dev/null
+++ b/tests/libutil/hex_decode.c
@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: GPL-3.0-or-later */
+/*
+ * hex_decode.c
+ *
+ * Copyright (C) 2022 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "config.h"
+#include "util/util.h"
+#include "util/test.h"
+
+static const struct {
+	int result;
+	const char *in;
+	const char *out;
+} test_vec[] = {
+	{ 0, "", NULL },
+	{ -1, "A", NULL },
+	{ 0, "AA", "\xAA" },
+	{ 0, "0A", "\x0A" },
+	{ 0, "A0", "\xA0" },
+	{ -1, "A0B", NULL },
+	{ 0, "A0BC", "\xA0\xBC" },
+	{ 0, "0123456789ABCDEF", "\x01\x23\x45\x67\x89\xAB\xCD\xEF" },
+	{ 0, "0123456789abcdef", "\x01\x23\x45\x67\x89\xAB\xCD\xEF" },
+	{ -1, "0123456789ABCDEFGH", NULL },
+	{ -1, "0123456789abcdefgh", NULL },
+};
+
+int main(int argc, char **argv)
+{
+	sqfs_u8 buffer[256];
+	size_t i, j;
+	(void)argc; (void)argv;
+
+	for (i = 0; i < sizeof(test_vec) / sizeof(test_vec[0]); ++i) {
+		size_t in_len = strlen(test_vec[i].in);
+		size_t out_len = in_len / 2;
+		int ret;
+
+		/* initialize the buffer */
+		for (j = 0; j < sizeof(buffer); ++j) {
+			buffer[j] = (j % 2) ? 0xAA : 0x55;
+		}
+
+		/* convert */
+		ret = hex_decode(test_vec[i].in, in_len,
+				 buffer, sizeof(buffer));
+
+		/* make sure pattern is un-touched after expected offset */
+		for (j = out_len; j < sizeof(buffer); ++j) {
+			TEST_ASSERT(buffer[j] == ((j % 2) ? 0xAA : 0x55));
+		}
+
+		/* check result */
+		if (test_vec[i].result == 0) {
+			TEST_ASSERT(ret == 0);
+			ret = memcmp(buffer, test_vec[i].out, out_len);
+			TEST_ASSERT(ret == 0);
+		} else {
+			TEST_ASSERT(ret != 0);
+		}
+	}
+
+	return EXIT_SUCCESS;
+}
+