1 files changed, 35 insertions, 0 deletions

diff --git a/libbb/xfuncs.c b/libbb/xfuncs.c
index aac46f414..aec165f06 100644
--- a/libbb/xfuncs.c
+++ b/libbb/xfuncs.c
@@ -122,6 +122,41 @@ char* FAST_FUNC bin2hex(char *p, const char *cp, int count)
         return p;
 }
 
+/* Convert "[x]x[:][x]x[:][x]x[:][x]x" hex string to binary, no more than COUNT bytes */
+char* FAST_FUNC hex2bin(char *dst, const char *str, int count)
+{
+        errno = EINVAL;
+        while (*str && count) {
+                uint8_t val;
+                uint8_t c = *str++;
+                if (isdigit(c))
+                        val = c - '0';
+                else if ((c|0x20) >= 'a' && (c|0x20) <= 'f')
+                        val = (c|0x20) - ('a' - 10);
+                else
+                        return NULL;
+                val <<= 4;
+                c = *str;
+                if (isdigit(c))
+                        val |= c - '0';
+                else if ((c|0x20) >= 'a' && (c|0x20) <= 'f')
+                        val |= (c|0x20) - ('a' - 10);
+                else if (c == ':' || c == '\0')
+                        val >>= 4;
+                else
+                        return NULL;
+
+                *dst++ = val;
+                if (c != '\0')
+                        str++;
+                if (*str == ':')
+                        str++;
+                count--;
+        }
+        errno = (*str ? ERANGE : 0);
+        return dst;
+}
+
 /* Return how long the file at fd is, if there's any way to determine it. */
 #ifdef UNUSED
 off_t FAST_FUNC fdlength(int fd)