[PATCH v3 06/11] lib: Add hextobarray() function

[lukas.funke-oss at weidmueller.com]

From: Lukas Funke <lukas.funke at weidmueller.com>

Add a 'hextobarray()' function which converts a hex string to it's
memory representation. This can be used to represent large integer
numbers or bitmasks which do not fit in a regular unsigned long value.

Signed-off-by: Lukas Funke <lukas.funke at weidmueller.com>
---

(no changes since v1)

 include/vsprintf.h |  7 +++++++
 lib/strto.c        | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 42 insertions(+)

diff --git a/include/vsprintf.h b/include/vsprintf.h
index ed8a060ee1..82c8bf029e 100644
--- a/include/vsprintf.h
+++ b/include/vsprintf.h
@@ -368,4 +368,11 @@ int vsscanf(const char *inp, char const *fmt0, va_list ap);
  */
 int sscanf(const char *buf, const char *fmt, ...);
 
+/**
+ * hextobarray - Convert a hex-string to a byte array
+ * @cp:		hex string to convert
+ * Return: a pointer to a byte array, -ENOMEM on error
+ */
+uchar *hextobarray(const char *cp);
+
 #endif
diff --git a/lib/strto.c b/lib/strto.c
index 5157332d6c..eb507e4ab8 100644
--- a/lib/strto.c
+++ b/lib/strto.c
@@ -13,6 +13,7 @@
 #include <malloc.h>
 #include <vsprintf.h>
 #include <linux/ctype.h>
+#include <linux/err.h>
 
 /* from lib/kstrtox.c */
 static const char *_parse_integer_fixup_radix(const char *s, uint *basep)
@@ -73,6 +74,40 @@ ulong simple_strtoul(const char *cp, char **endp, uint base)
 	return result;
 }
 
+uchar *hextobarray(const char *cp)
+{
+	int i, len;
+	__maybe_unused unsigned int base;
+	__maybe_unused const char *endptr;
+	unsigned char *array;
+
+	len = strlen(cp);
+	array = (unsigned char *)malloc(len);
+	if (!array)
+		return ERR_PTR(-ENOMEM);
+
+	memset(array, 0, len);
+
+#if __BYTE_ORDER == __LITTLE_ENDIAN
+	endptr = (cp + len - 1);
+	for (i = 0; i < len && endptr > cp; i++) {
+		array[i] |= decode_digit(*(endptr));
+		endptr--;
+		array[i] |= decode_digit(*endptr) << 4;
+		endptr--;
+	}
+#else
+	cp = _parse_integer_fixup_radix(cp, &base);
+	for (i = 0; i < len && *cp; i++) {
+		array[i] |= decode_digit(*cp) << 4;
+		cp++;
+		array[i] |= decode_digit(*cp);
+		cp++;
+	}
+#endif
+	return array;
+}
+
 ulong hextoul(const char *cp, char **endp)
 {
 	return simple_strtoul(cp, endp, 16);
-- 
2.30.2