helper: Make unhexify() robust on invalid data

[fw/openocd] / src / helper / binarybuffer.c

diff --git a/src/helper/binarybuffer.c b/src/helper/binarybuffer.c
index c1e6322658ab1b22b4609e725975ba4fc72b4bbd..26aa8ccede30ce7f236da74ecbaf9aadae6095d8 100644 (file)
--- a/src/helper/binarybuffer.c
+++ b/src/helper/binarybuffer.c
@@ -369,17 +369,42 @@ void bit_copy_discard(struct bit_copy_queue *q)
        }
 }
 
-int unhexify(char *bin, const char *hex, int count)
+/**
+ * Convert a string of hexadecimal pairs into its binary
+ * representation.
+ *
+ * @param[out] bin Buffer to store binary representation. The buffer size must
+ *                 be at least @p count.
+ * @param[in] hex String with hexadecimal pairs to convert into its binary
+ *                representation.
+ * @param[in] count Number of hexadecimal pairs to convert.
+ *
+ * @return The number of converted hexadecimal pairs.
+ */
+size_t unhexify(uint8_t *bin, const char *hex, size_t count)
 {
-       int i, tmp;
+       size_t i;
+       char tmp;
 
-       for (i = 0; i < count; i++) {
-               if (sscanf(hex + (2 * i), "%02x", &tmp) != 1)
-                       return i;
-               bin[i] = tmp;
+       if (!bin || !hex)
+               return 0;
+
+       memset(bin, 0, count);
+
+       for (i = 0; i < 2 * count; i++) {
+               if (hex[i] >= 'a' && hex[i] <= 'f')
+                       tmp = hex[i] - 'a' + 10;
+               else if (hex[i] >= 'A' && hex[i] <= 'F')
+                       tmp = hex[i] - 'A' + 10;
+               else if (hex[i] >= '0' && hex[i] <= '9')
+                       tmp = hex[i] - '0';
+               else
+                       return i / 2;
+
+               bin[i / 2] |= tmp << (4 * ((i + 1) % 2));
        }
 
-       return i;
+       return i / 2;
 }
 
 int hexify(char *hex, const char *bin, int count, int out_maxlen)