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-rw-r--r--lib/util/hex_decode.c34
1 files changed, 34 insertions, 0 deletions
diff --git a/lib/util/hex_decode.c b/lib/util/hex_decode.c
new file mode 100644
index 0000000..ee4b21c
--- /dev/null
+++ b/lib/util/hex_decode.c
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: LGPL-3.0-or-later */
+/*
+ * hex_decode.h
+ *
+ * Copyright (C) 2022 David Oberhollenzer <goliath@infraroot.at>
+ */
+#include "util/util.h"
+
+#include <ctype.h>
+
+static sqfs_u8 xdigit(int in)
+{
+ if (isupper(in))
+ return in - 'A' + 10;
+ if (islower(in))
+ return in - 'a' + 10;
+ return in - '0';
+}
+
+int hex_decode(const char *in, size_t in_sz, sqfs_u8 *out, size_t out_sz)
+{
+ while (out_sz > 0 && in_sz >= 2 &&
+ isxdigit(in[0]) && isxdigit(in[1])) {
+ sqfs_u8 hi = xdigit(*(in++));
+ sqfs_u8 lo = xdigit(*(in++));
+
+ *(out++) = (hi << 4) | lo;
+
+ in_sz -= 2;
+ --out_sz;
+ }
+
+ return (in_sz > 0) ? -1 : 0;
+}