add hex_to_str

docs/crypto.md

@@ -57,3 +57,12 @@ for (size_t i = 0; i < 4; ++i) {
 }
 free(s);
 ```
+
+### hex_to_str
+
+Converts an array of `unsigned char` into a string based on the ASCII values of each byte. User is
+responsible for freeing the returned string.
+
+```c
+const char *hex_to_str(const unsigned char *hex, size_t sz);
+```

include/lfcrypto.h

@@ -5,7 +5,9 @@
 
 const char *b64_encode(const unsigned char *s, size_t sz);
 unsigned char *b64_decode(const char *s, size_t sz, size_t *decode_sz);
+
 const char *hex_encode(const unsigned char *hex, size_t sz);
 unsigned char *hex_decode(const char *orig, size_t *sz);
+const char *hex_to_str(const unsigned char *hex, size_t sz);
 
 #endif // LIBFLINT_CRYPTO_H

src/crypto.c

@@ -243,3 +243,12 @@ const char *hex_encode(const unsigned char *hex, size_t sz) {
 
     return s;
 }
+
+const char *hex_to_str(const unsigned char *hex, size_t sz) {
+    char *s = malloc(sizeof(char) * (sz + 1));
+    for (size_t i = 0; i < sz; ++i) {
+        s[i] = (char)hex[i];
+    }
+    s[sz] = '\0';
+    return s;
+}

tests/tests.c

@@ -349,6 +349,14 @@ void test_crypto() {
     s = hex_encode(h, 4);
     assert(strcmp(s, "DEADBEEF") == 0);
     free(s);
+
+    // "Sup?"
+    unsigned char hexsup[4] = {
+            0x53, 0x75, 0x70, 0x3F
+    };
+    s = hex_to_str(hexsup, 4);
+    assert(strcmp(s, "Sup?") == 0);
+    free(s);
 }
 
 #if defined(__APPLE__) || defined(__MACH__)